Where to nest?

pic whimbrelThere is nothing more obvious than an Oystercatcher sitting on his or her nest, but a brooding Snipe can be invisible until almost trodden upon. Which strategy works better: nesting in plain view but laying cryptically camouflaged eggs or hiding yourself and your nest in a clump of grass? Which species is most likely to hatch a successful brood of chicks and in what circumstances? In a 2020 paper in IBIS, Becky Laidlaw and colleagues analysed nest site characteristics and nest locations of 469 wader nests in Iceland in order to provide some answers

The perils of ground-nesting

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Hatching Whimbrel eggs, with the tell-tale shell fragments that signal a nesting attempt has been successful

Almost all waders are ground-nesters, which makes them highly vulnerable to a wide range of nest predators. To reduce the risks of predation, different strategies have evolved. In some species, nests are placed out in the open, and the camouflage is provided only by mottled egg colouration that resembles the background. In other species, nests are secreted in vegetation, meaning eggs and incubating adults are concealed from predators.

In both groups of species, the risk of nests being predated might vary, depending on the surrounding habitat. For open-nesting species, for example, clutches that are laid in large patches of similar habitat may be harder for predators to locate. The same could apply to closed-nest species that hide their nests; Snipe nests may be tricky to find in extensive areas of long grass but perhaps more at risk if there are only a few suitable clumps of long grass that predators need to check out.

pic hidden Redshank

Iceland: a wader factory

tableAs discussed in previous WaderTales blogs, particularly Do Iceland’s farmers care about wader conservation? Iceland is hugely important as a European ‘wader factory’. As farmland elsewhere has become less suitable for species such as Redshank and Snipe, the global importance of the country has increased (see table alongside for most recent figures from an AEWA report)  With this in mind, it is important to understand the factors that underpin the population dynamics of Iceland’s breeding waders.

Working in South Iceland, Becky Laidlaw and her co-authors tried to find as many nests as possible during the summers of 2015 and 2016. This area is largely a mosaic of open habitats, although there are more patches of forestry than there were twenty years ago. Most of the Southern Lowlands area is farmed, on a gradient between intensive and semi-natural, and this is reflected in the distribution of breeding waders (see Farming for waders in Iceland).

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Dragging a light rope across the vegetation to flush nesting birds

For this project, nests were located by surveys from vehicles and on foot, through observation of incubating adults, systematic searching, incidental flushing of incubating adults and rope-dragging (dragging a 25 m rope, held between two fieldworkers, lightly across vegetation) to flush incubating adults.

The analysis in the resulting paper in IBIS focuses on 469 nests of three open-nesting species (Oystercatcher, Golden Plover and Whimbrel) and three species that hide their nests in tall vegetation (Redshank, Snipe and Black-tailed Godwit). The team recorded the habitat and vegetation structure around each nest (at the nest, within a 5 m x 5 m square and in a wider 50 m x 50 m square) and worked out which nests hatched successfully and which were predated. The date and time of predation were determined, where possible, with nest-cameras providing extra information for some nests. Cameras captured nest-predation events involving Arctic foxes, Arctic Skuas, Ravens and sheep.

Interestingly, 2015 and 2016 were very different wader breeding seasons. The graphic below shows the mean temperatures for the months from April through to July (encompassing the wader breeding season at this latitude) were much cooler in 2015 than in 2016, representing average monthly difference of between 1.5°C and 2.5°C. At high latitudes these figures translate into very different rates of vegetation growth.

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First, find your nest

When nests were first located, their positions were marked and referenced using GPS. Eggs were floated in water to provide an estimate of laying date and thereby predict hatching date. As the chick develops within an egg, the density of the egg falls. A newly laid egg will lie on the bottom of the flotation vessel. Over the next few days the ‘blunt end’ rises until the egg is still touching the bottom but vertical. Eggs in the late-development stage float ‘point-end-down’, with the latest eggs floating at an angle to the vertical (method described by Liebezeit et al.).

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This Golden Plover nest was probably predated by an Arctic Skua

Nests were considered successful if one or more eggs hatched, and predated nests were defined as those that were empty in advance of the predicted hatch date or those without any eggshell fragments in the nest (a sign of successful hatching). To determine the time and date of nest failures, iButton dataloggers were placed in a randomly selected subsample of nests. These loggers recorded a temperature trace every ten minutes. A sharp and permanent decline in nest temperature below incubation temperature indicates nest predation. In both study years, motion-triggered cameras were deployed on a sample of open-nesting species to determine the predator species active on these nests.

When each nest was first located, the percentage of eggs visible from directly above the nest was estimated and the habitat surrounding each nest was assessed in the field at three spatial scales: the nest cup, the 5 m x 5 m and the 50 m x 50 m area surrounding each nest. Details are in the paper.

Which nests survive through to hatching?

Over the breeding seasons of 2015 and 2016, the outcomes of 469 wader nests were assessed. 259 hatched successfully (55%), 192 were predated (41%), 13 were abandoned, 7 were trampled and 2 were mown. A nest-loss rate of 40% is fairly typical for ground-nesting waders, when compared to studies in different countries and habitats.

pic fox attack

Daily nest predation rates did not vary significantly in relation to the habitat heterogeneity or the extent to which the dominant habitat covered the area surrounding the nest, at either 5 m x 5 m or 50 m x 50 m scales. Most clutches were laid in habitats that were the same or similar to the surrounding areas. Where there were differences, the dissimilarity between the habitat at the nest cup and in the surrounding area did not influence daily nest predation rates for open- or closed-nest species. Although nest predation is high, at about 40%, incidence of predation events appears to be unpredictable – or even random.

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In cold spring conditions, Icelandic Snipe are not able to hide their nests

Daily nest predation rates were significantly higher for closed nests (Redshank, Snipe and Black-tailed Godwit nests) in which a greater percentage of the clutch was visible. This suggests that the onset and rate of vegetation growth could potentially constrain the availability of suitable nesting locations for these species, and hence influence nest success, particularly among early season nests. This has been studied in Icelandic Black-tailed Godwits by José Alves and colleagues and is described in From local warming to range expansion.

For closed-nest species, the visibility of nests was significantly greater during the early part of the 2015 breeding season, when compared to 2016, due to slower grass growth in cooler conditions.  The higher predation rate of more visible nests of closed-nesting species was apparent even though nests were predated up to three weeks after egg visibility was measured. These findings suggest that early nesting attempts by concealed-nest species are unlikely to be successful in years when vegetation growth is delayed or slow. There can be major benefits of hatching early, with recruitment into breeding populations typically being lower for later-hatched chicks, so vegetation growth rates are likely to be really important to species that conceal their nests (Redshank, Snipe & Black-tailed Godwit in this study). However, given the ongoing trend for warmer springs at subarctic latitudes, the conditions in which early nests can only be poorly concealed are likely to be reducing in frequency.

In summary

pic goldie nest in habitat

Golden Plover nest set within a homogeneous habitat matrix

Perhaps surprisingly, nest predation rates were similar for open-nest and concealed-nest species and did not vary with vegetation structure in the surrounding landscape. However, nest-concealing species were about 10% more likely to have nests predated when the nests were poorly concealed, and the frequency of poorly concealed nests was higher at the start of the breeding season in colder conditions.

The paper at the heart of this blog is:

Vegetation structure influences predation rates of early nests in subarctic breeding waders. Rebecca A. Laidlaw, Tómas G. Gunnarsson, Verónica Méndez, Camilo Carneiro, Böðvar Þórisson, Adam Wentworth, Jennifer A. Gill and José A. Alves. IBIS. doi:10.1111/ibi.12827

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GFA in Iceland

WaderTales blogs are written by Graham Appleton, to celebrate waders and wader research.  Many of the articles are based on previously published papers, with the aim of making wader science available to a broader audience.

@grahamfappleton

 

 

Black-tailed Godwits are on their way home

bg topAs I write this, at the start of March 2020, spring is on its way – and so are limosa Black-tailed Godwits. Many have flown north from wetlands and rice-fields in West Africa and are now fattening and moulting in a small number of sites in Portugal, France and Spain. The vast majority are heading for the Netherlands but a few will ‘bear left’ and end up in East Anglia.

The biggest spring flocks of limosa Black-tailed Godwits are found on the Tagus (or Tejo) Estuary, in Portugal, a site that is under threat from a planned airport development. Swirling flocks of up to 80,000 birds create a wildlife spectacle that attracts an increasing number of tourists. Among these ranks of telescope-wielding birdwatchers is a small band of dedicated colour-ring readers from the Netherlands working on a University of Groningen / Global Flyway Network project. They are looking for marked Black-tailed Godwits (Grutto in Dutch) that are part of their conservation science project; some of these Grutto are old friends, others will have been ringed as chicks and are now heading north for the first time.

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This year, the Dutch team working in Portugal in mid-February spotted ten Project Godwit birds – Black-tailed Godwits that belong to the tiny and highly threatened population that breed in the Ouse and Nene Washes. An increasing number of these sightings of English birds are of ‘head-started’ godwits; birds that started life as eggs in nests on the RSPB’s Nene Washes reserve and were then hatched in incubators and reared in captivity at the Wildfowl & Wetland Trust’s Welney reserve. You can read more about head-starting here.

Before telling some fascinating individual stories, here’s a quick reminder that conservation operations in The Netherlands, the UK and elsewhere might be jeopardised by a plan to build a second airport for Lisbon, within the Tagus Estuary – one of the top wetlands in Europe and a critical stopover site for limosa godwits.

Birds v Planes

bg petitionMillions of euros – and a smaller number of pounds – are spent each year in support of the dwindling populations of limosa Black-tailed Godwits that breed in the Netherlands, here in the UK and in other countries within Europe. Much of the money is helping ‘meadow birds’ in general but there are specific interventions to protect godwit nests and chicks during farming operations in the Netherlands and to boost chick production in England. These huge (and often expensive) conservation efforts are potentially being threatened by a plan to build the so-called Montijo Airport in the heart of the Tagus Estuary. This is where up to 80,000 Black-tailed Godwits gather in spring and several thousand spend the winter. You can read more about the planned airport and the importance of the area to migratory waders and other waterbirds in Tagus estuary – for birds or planes?

You can support the Dutch initiative to stop the new airport by signing the petition being organised by Vogelbescherming, the BirdLife partner in the Netherlands. Link here.

Last chance for England’s breeding Black-tailed Godwits

When Project Godwit started in 2017, there were only 38 pairs of Black-tailed Godwit breeding in East Anglia, mostly on the Nene Washes, with a small number on the Ouse Washes. Despite huge efforts by conservation organisations, and the RSPB in particular, productivity was consistently very low. Predation and flooding were the main challenges; there was a real prospect of ageing birds failing to raise enough youngsters to maintain the viability of the population. While work continued to create alternative flood-free breeding areas at the Ouse Washes and to tackle predation issues, these godwits needed a boost. That’s where head-starting comes in; by removing first clutches, incubating the eggs, raising the chicks and releasing them back onto the Nene and Ouse Washes, once fledged, it proved possible to greatly increase the number of young birds that headed south for the winter.

Sep2019

At the start, there was no guarantee that head-starting would work. The first WaderTales blog about Project Godwit was a plea for birdwatchers to look out for colour-ringed, head-started chicks, the second asked whether the released chicks would be able to find their way back to East Anglia and the third celebrated early successes.

  1. Special Black-tailed Godwits
  2. Site-fidelity in Black-tailed Godwits
  3. Head-starting success

The success of these special head-started Black-tailed Godwits has been enjoyed by millions who watch the BBC’s Springwatch series and thousands of visitors to the WWT centre at Welney. In addition, individual godwits have played starring roles in newspaper and magazine articles and on local television news programmes.

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Migration

bg SenegalOne of the big take-home messages from Project Godwit is that head-started chicks, released back on the Ouse and Nene Washes, soon mix with wild-reared birds and adults.  Information collected so far suggests that head-started birds follow similar migration patterns to the wild godwits.  Most limosa Black-tailed Godwits travel south to countries in West Africa, especially Senegal, and then fly north after Christmas, to Portugal and Spain.  Some may make another stop in France, before reaching their territories. An increasing proportion of the main Dutch population is now wintering in Europe (Should Black-tailed Godwits cross the Sahara?). Dutch and Iberian researchers are using satellite tracking to monitor day-to-day movements (King of the Meadows)

Birds on the Tagus in 2020

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Black-tailed Godwits feeding in a Tagus rice-field

Some limosa Black-tailed Godwits spend the winter on the Tagus but big flocks do not start to build until the start of the new year, as birds return from Africa. The ten colour-ringed Project Godwit individuals that were seen by the Dutch team between 2nd and 10th of February 2020 were a mixture of old friends and birds that had not been seen on the rice fields before. Flocks of 30,000 or more Black-tailed Godwits can descend upon a single rice-field, post-harvest, to feed on spilt grain and invertebrates. It is not easy to spot colour-ringed birds in the melee of legs, as birds wade through the water, and it is very likely that there were many more Washes birds that were not spotted. The ten Project Godwit birds were seen alongside hundreds being studied by Dutch conservation scientists. So, which individual godwits were seen?

Class of 2017

Two head-started chicks from the first year of the project were seen in February 2020. One of them was YG-GL(E) or Remi (click on her name to read her story), who starred in the WaderTales blog Site-fidelity in Black-tailed Godwits. We know that she is one of the majority of Black-tailed Godwits that fly to West Africa because she was also spotted in Senegal in November 2019. A total of 24 head-started birds were released in the summer of 2017 and six of them have now been seen on the Tagus.

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Class of 2018

bg HurricaneIn the summer of 2018, 38 head-started chicks were released and two of them were seen this February in the Tagus rice-fields. One of these was WG-WL(E) or Hurricane, a bird that spent his first summer near Valencia in Spain before departing in mid-June. Some Black-tailed Godwits fly north in their first spring but many do not. After months of Spanish sunshine, Hurricane may well have flown south with an early flock of post-breeding adults, moving through to West Africa in the late summer,  and that the Dutch team spotted him on his way back to the Washes. Two other head-started birds from the second year of the project have been seen on the Tagus, making a total of four.

Class of 2019

The 48 head-started birds from 2019 are still only a few months old. Some might be on their way back to the Washes but there were no sightings in early February. It has been suggested that birds that do migrate north to breed in their first year might be on a slightly later schedule, so perhaps later teams of Dutch observers might report one or more of these birds.

Wild chicks 2017-2019

bg ad chicksThe Project Godwit team try to ring as many as possible of the wild-reared chicks on the Nene Washes, so that they can compare their behaviour patterns to those of the captive-reared group. Two of the wild-reared birds have been seen on the Tagus; a chick from 2018 was reported in both 2019 and 2020, and a chick from 2019 was seen in the autumn of 2019.

Earlier chicks

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Two members of the Dutch team of colour-ring readers: Rienk Jelle Hibma & Teade de Boer

The RSPB has been studying Black-tailed Godwits for over twenty years. One of the very early chicks was spotted in the rice-fields this February. LG-RL(E) was ringed 21 years ago and she had previously been reported in the Tagus estuary in the springs of 2017, 2018 and 2019, and in the autumn of 2018. Black-tailed Godwits are known to live for up to 25 years.

Ringed as adults

RSPB researchers also ring adults by catching them on their nests. Four birds ringed in this way were seen on the Portuguese rice-fields in February 2020. Adding in four head-started chicks, and two chicks that was raised in the wild, this makes a total of ten birds from the Ouse and Nene Washes that are known to have visited the Tagus Estuary during this spring.

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There are two colour-ringed birds in this photograph

One that won’t be seen again

RY-OL(E) was ringed in 2002 and spotted in the Tagus in February 2018. She has been a key contributor to Project Godwit over the last few years, fledging two chicks in the wild in 2018 and three in 2019. Additionally, she provided four extra young godwits via the head-starting process in 2018. Her metal-ringed leg was recently found in a Peregrine nest in Brighton. Presumably she became a meal for a young Peregrine in the late summer of 2019.

Conservation importance of the Tagus Estuary

In February, the Tagus is thought to hold half of what is left of the Dutch population of Black-tailed Godwits, when up to 80,000 birds move around the estuary in huge flocks. Colour-ring reports and sighting probabilities suggest that around half of the Project Godwit birds, heading for the Ouse and Nene Washes, may also rely on the mud-flats and surrounding rice-fields in the early spring.

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Project Godwit has already given a terrific boost to the Black-tailed Godwits breeding in England, with the number of pairs up from 38 in 2017 to 45 in 2019, and it seems ridiculous that much of the good work could be put at risk if Montijo Airport is built. It is sad that a five-year project, that has involved over 20 dedicated RSPB and WWT staff , together with local volunteers and observers in the UK, Europe and Africa, might be in jeopardy.

Project Godwit has received major funding from the EU LIFE Nature Programme, HSBC 150th Anniversary Fund, Natural England, the Heritage Lottery Fund (through the Back from the Brink Programme) and Leica UK. The Dutch team of colour-ring readers in February 2020 was: Jan Vegelin, Kees de Jager, Egbert van der Velde, Rienk Jelle Hibma, Teade de Boer, Bob Loos & Jacob de Vries.  Their work is directed by Jos Hooijmeijer and funded by the University of Groningen and the Global Flyway Network.

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GFA in Iceland

WaderTales blogs are written by Graham Appleton, to celebrate waders and wader research.  Many of the articles are based on previously published papers, with the aim of making wader science available to a broader audience.

@grahamfappleton

Nine red-listed UK waders

blog rpIf you ask British birdwatchers to name the nine wader species that are causing the most conservation concern in the UK, they would probably not include the Ringed Plover. Curlew may well be top of the list, even though we still have 58,500 breeding pairs in the UK*, but would people remember to include Ruff? This blog is written to coincide with the publication of Red67, an amazing collaboration of artists and essayists that highlights and celebrates the 67 species on the current UK red list, nine of which are waders.

*Avian Population Estimates Panel report (APEP4) published in British Birds

What’s a Red List?

The UK Red List is made up of a strange mixture of common and rare species. Nobody will be surprised to see fast-disappearing Cuckoo, Turtle Dove and Willow Tit, but why are 5.3 million pairs of House Sparrow in the same company? The list is very important because it helps to set the agenda for conservation action, the way that money for research is distributed and focuses attention during planning decisions. The main criteria for inclusion are population size – hence the inclusion of species that are just hanging on in the UK, such as Golden Oriole – and the speed of decline of common species. Data collected by volunteers, working under the auspices of the British Trust for Ornithology, measured a population decline for House Sparrow of 70% between 1977 and 2017, which is worrying enough to earn this third most numerous breeding species in the UK a place in Red67.

blog bookIn his foreword to Red67, Mark Eaton, Principal Conservation Scientist for RSPB, explains how listing works. The Birds of Conservation Concern (BOCC) system, through which the Red List and Amber List are determined, uses a strict set of quantitative criteria to examine the status of all of the UK’s ‘regularly’ occurring species (scarce migrants and vagrants aren’t considered), and uses a simple traffic light system to classify them. There are ‘Red’ criteria with thresholds for rates of decline in numbers and range, historical decline and international threat (if a species is considered globally threatened it is automatically Red-listed in the UK), together with a range of other considerations such as rarity, international importance of UK populations, and how localised a species is. If a species meets any of the Red List criteria it goes onto the Red List.

The Red67 book – words meet art

Red67 is the brainchild of Kit Jewitt, a.k.a. @YOLOBirder on Twitter. It’s a book featuring the 67 Red-listed birds, each illustrated by a different artist alongside a personal story from a diverse collection of writers. Proceeds will support Red-listed species conservation projects run by BTO and RSPB. Kit describes Red67 as 67 love letters to our most vulnerable species, each beautifully illustrated by some of the best wildlife artists around, showcasing a range of styles as varied as the birds in these pages. My hope is that the book will bring the Red List to a wider audience whilst raising funds for the charities working to help the birds most at need.

This blog is about the nine waders in the book, but there are 58 other fascinating species accounts and wonderful artworks. Each species account starts with a quote from the story in the book and is accompanied by a low-resolution version of the artwork (Ringed Plover is illustrated above).

Lapwing

blog l“It’s the crest that does it for me – that flicked nib stroke, the artist’s afterthought” – Lev Parikian

The Lapwing used to nest across the whole of the United Kingdom and was a common bird in almost every village. It’s still the most numerous breeding wader in the UK, with 97,500 pairs (APEP4), beating Oystercatcher by just 2,000 pairs. Numbers dropped by 54% between 1967 and 2017, according to BirdTrends 2019, published by BTO & JNCC. Huge losses had already occurred over the previous two centuries, as land was drained and vast numbers of eggs were collected for the table. The Lapwing is now a bird associated with lowland wet grasslands and the uplands, rather than general farmland.

Red-listing has been important for Lapwing, increasing the profile of the species and encouraging the development of specific agri-environment schemes targeted at species recovery. These include ‘Lapwing plots’ in arable fields and funding to raise the summer water tables in lowland grassland. Several WaderTales blogs describe efforts to try to increase the number of breeding waders in wet grassland, especially Toolkit for Wader Conservation. The loss of waders, and Lapwings in particular, from general farmland is exemplified in 25 years of wader declines.

Ringed Plover

blog rp graph“They gather at high tide like shoppers waiting for a bus: all facing the same direction, and all staring into the distance” – Stephen Moss

One of the criteria that the BOCC panel takes into account, when constructing the Red List, is the responsibility the UK has for a species or subspecies in the breeding season, during winter or both. The Ringed Plovers we see in the UK in the winter are almost exclusively of the hiaticula subspecies; birds that breed in southern Scandinavia, around the Baltic, in western Europe and in the UK. There are only estimated to be 73,000 individuals in this subspecies, so the 42,500 that winter in the UK constitutes a large percentage of the Ringed Plovers that breed in many of these countries.

The Wetland Bird Survey graph alongside shows a decline of over 50% between 1989 and 2014. At the start of the period, Ringed Plover numbers were at an all-time high but this is still a dramatic and consistent drop. Numbers have stabilised and may even have increased slightly but Ringed Plovers need some good breeding years. Disturbance is an issue for breeding Ringed Plovers, which share their beaches with visitors and dogs, and could also potentially be a problem in the winter (see Disturbed Turnstones).

Dotterel

blog dot“I want you in the mountains. Summer breeze. At home. Doing your thing. So don’t go disappearing on us, okay?” – Fyfe Dangerfield

The Dotterel is a much clearer candidate for Red67 – there’s a small population in a restricted area and numbers have fallen. The detailed reasons for decline may still need to be nailed down but candidate causes such as declining insect food supplies and the increasing numbers of generalist predators are probably all linked to a changing climate – squeezing Dotterel into a smaller area of the mountain plateaux of Scotland.

There’s a blog about the decline in Dotterel numbers called UK Dotterel numbers have fallen by 57%, based upon a paper that uses data up until 2011. At this point, the population was estimated at between 280 and 645 pairs. There has been no suggestion of improvement since that blog was written. Interestingly, Dotterel may have a way out of their predicament, as we know that marked individuals move between Scotland and Norway in the same breeding season.

Whimbrel

blog whim“How often do Whimbrels pass overhead nowadays? Unseen and unheard, their calls mean nothing to most of us” – Patrick Barkham

Most British and Irish birdwatchers think of Whimbrel as spring migrants, enjoying seeing flocks of Icelandic birds when they pause on their way north from West Africa (see Iceland to Africa non-stop). There is a small, vulnerable population nesting almost exclusively on Shetland. The latest estimate is 310 pairs (2009), down from an estimate of 530 pairs, published in 1997. Many pairs have been lost from Unst and Fetlar and this blog about habitat requirements, based on RSPB research, might give clues as to why: Establishing breeding requirements of Whimbrel.

The curlew family is in trouble across the Globe, potentially because these big birds need so much space (see Why are we losing our large waders?)

Curlew

blog cu“… achingly vulnerable in a world that is battling to hold onto loveliness” – Mary Colwell

What more can be said about Curlew, ‘promoted’ to the red list in 2015 and designated as ‘near threatened’ globally. Most significant is the story from Ireland, where 94% of breeding birds have disappeared in just 30 years. These blogs provide more information about the decline and review some of the reasons.

There are more Curlew-focused blogs in the WaderTales catalogue.

Black-tailed Godwit

blog blackw“A glimpse of terracotta is obscured by ripples of grass, dipping gently in the breeze” – Hannah Ward

Winter Black-tailed Godwit numbers are booming but these are islandica – birds that have benefited from warmer spring and summer conditions in Iceland, as you can read here in: From local warming to range expansion. Their limosa cousins are in trouble in their Dutch heartlands (with declines of 75%) and there have been similar pressures on the tiny remaining breeding populations in the Ouse and Nene Washes. Here, a head-starting project is boosting the number of chicks; so much so that released birds now make up a quarter of this fragile population. Red-listing has shone a spotlight on this threatened subspecies, attracting the funding needed for intensive conservation action.

Ruff

blog ruff“They look a bit inelegant – a small head for a decently sized bird, a halting gait, and that oddly vacant face” – Andy Clements

There are two ways for a species to be removed from the Red List – extirpation (extinction in the UK) and improvement. Temminck’s Stint came off the list in 2015, having not been proven to breed since 1993, and Dunlin was moved to Amber at the same time. Ruff are closer to extirpation than they are to the Amber list. There is a spring passage, mostly of birds migrating from Africa to Scandinavia and the Baltic countries, and some males in glorious breeding attire will display in leks.

250 years ago, Ruff were breeding between Northumberland and Essex, before our ancestors learnt how to drain wetlands and define a hard border between the North Sea and farmland. Hat-makers, taxidermists and egg-collectors added to the species’ woes and, by 1900, breeding had ceased. The 1960s saw a recolonisation and breeding Ruff are still hanging on. There are lekking males causing excitement in sites as disparate as Lancashire, Cambridgeshire and Orkney, and there are occasional nesting attempts. Habitat developments designed to help other wader species may support Ruff but the situation in The Netherlands does not suggest much of a future. Here, a once-common breeding species has declined to an estimated population of 15 to 30 pairs (Meadow birds in The Netherlands).

Red-necked Phalarope

blog rnp“… snatching flies from the water in fast, jerky movements, droplets dripping from its slender beak” – Rob Yarham

Red-necked Phalaropes that breed in Shetland and a few other parts of northern Scotland appear to be an overflow from the Icelandic population; birds which migrate southwest to North America and on to the Pacific coastal waters of South America. This BOU blog describes the first track revealed using a geolocator.

The Red-necked Phalarope was never a common breeder and came under pressure from egg-collectors in the 19th Century. Numbers are thought to have recovered to reach about 100 pairs in Britain & Ireland by 1920. Numbers then fell to about 20 pairs by 1990, so the latest estimate of 64 pairs (The Rare Breeding Birds Panel) reflects conservation success. Given the restricted breeding range and historical declines, it is unlikely that the next review will change the conservation status from Red to Amber, despite the recovery of numbers.

Woodcock

blog wk“… taking the earth’s temperature with the precision of a slow, sewing-machine needle” – Nicola Chester

The presence of Woodcock on the Red List causes heated debate; how can this still be a game species? Red-listing is indisputable; the latest survey by BTO & GWCT showed that there was a decline in roding males from 78,000 in 2003 to 55,000 in 2013, with the species being lost from yet more areas of the UK. Each autumn, the number of Woodcock in the UK rises massively, with an influx of up to 1.4 million birds. Annual numbers depend upon seasonal productivity and conditions on the other side of the North Sea. A recent report on breeding wader numbers in Norway, Sweden and Finland, shows that breeding populations of Woodcock in this area are not declining (Fennoscandian wader factory).

The UK’s breeding Woodcock population is under severe threat from things such as increased deer browsing and drier ground conditions but winter numbers appear to be stable. The difference in conservation status between breeding and wintering populations is reflected in the fact that Woodcock is on both the Red List and the Quarry List, for now. There is a WaderTales blog (Conserving British-breeding Woodcock) that discusses ways to minimizes hunting effects on British birds. These guidelines from GWCTemphasise the importance of reducing current pressures on British birds.

In conclusion

blog bookThe Red List creates some strange bedfellows. In the book, Turtle Dove follows Herring Gull; a bird with links to love and romance and another with at best the charm of a roguish pirate. But the List works; it creates an evidence-base that help those who devise agricultural subsidy systems, advise on planning applications, license bird control and prioritise conservation initiatives.

Red67 seeks to raise awareness of the UK’s most at-risk bird species, nine of which are waders, and to raise money for BTO and RSPB scientists to carry out important research. It’s a lovely book that captures the thoughts and images of a generation of writers and artists. You can learn more about the project, order the book and buy some Red Sixty Seven products by clicking here.


GFA in IcelandGraham (@grahamfappleton) has studied waders for over 40 years and is currently involved in wader research in the UK and in Iceland.  He was Director of Communications at The British Trust for Ornithology until 2013 and is now a freelance writer and broadcaster.

 

 

Tagus estuary: for birds or planes?

blog samoucoA planned new airport that will serve Lisbon threatens the future of internationally important flocks of waders and other waterbirds. These same birds pose safety concerns for the passenger aircraft that will fly through the airspace that is currently reserved for them.

The development site of the proposed Montijo airport abuts the part of the Tagus/Tejo estuary that is designated as a Special Protection Area (SPA) and an Important Bird Area (IBA). This designation is based upon counts of 49,000 Black-tailed Godwits, 12,000 Dunlin, 6000 Avocet, 4500 Wigeon, 3300 Greylag Geese, 2000 Grey Plover and 1600 Greater Flamingos. That’s 23 tonnes of birds, representing just a few key species, before you add in gulls, Spoonbills and up to 6,000 Glossy Ibises. This blog focuses upon the importance of the Tagus/Tejo Estuary for just one of the species, the Black-tailed Godwit.

blog map

The planning process

At first sight, turning the air force base in Montijo into a commercial airport looks like an obvious option, given that planes already take off and land there. However, the runway will need to be longer, there will have to be a vast new infrastructure and planes will be landing every few minutes, rather than during scheduled periods of military training. There will be some habitat removal, and it will be hard to avoid run-off of fuel and chemicals into the estuary, but the big problem will be disturbance of the flocks of birds within this IBA, as planes land and take-off and when airport employees frighten away flocks that are too close to the main flight-paths. Each time a flock of birds takes to the air, a large amount of fuel is burnt – as fat laid down for migration is wasted.

blog flamingoPlanes and birds do not mix, as we saw on 15 January 2009, when US Airways Airbus Flight 1549 landed on the Hudson River after an encounter with Canada Geese. How many Greater Flamingos will it take to stop a jet engine? Each one weighs about three kilogrammes and there are 1600 on the SPA, many within a few hundred metres of the airport site.

Around the world, there have been many bird/plane incidents, some causing significant loss of (human) life, which explains why there’s not a ‘Boris Island Airport’ in the Thames Estuary. History suggests that bird-strike risks are underplayed at the planning stage but have to be coped with later. Once the airport is operational, it is likely that nests will be removed and attempts will be made to disperse flocks through disturbance and shooting.

Icelandic Black-tailed Godwits

The Tagus is particularly important for Black-tailed Godwits. Although the published count, associated with the designation of the estuary, is 49,000, it is agreed that the maximum late-winter number for the estuary and surrounding rice fields is now 70,000 or more, which includes birds of both the islandica and limosa races.

mapThere are Black-tailed Godwits on the Tagus during every month of the year. Numbers are lowest in the summer, chiefly comprising young islandica birds that do not travel back to Iceland in their first spring. Adults arrive back from Iceland between July and November, the later birds having stopped off to moult in sites such as the Wash (Eastern England) and coastal France. Numbers drop again as early as January, when adults move to the Netherlands and England, to fatten up for the trip back across the Atlantic to Iceland. There is a blog about this ‘overtake manoeuvre’ and the advantages it confers.

Given that islandica Black-tailed Godwits can spend the winter anywhere between Scotland and the south of Spain, it could be argued that disturbance on the Tagus, to try to disperse flocks, would be no big problem, as there are other places for individuals to spend the winter. Two things are wrong with this theory. Firstly, as was described in Generational Change, individual Black-tailed Godwits are creatures of habit, typically using a suite of about four non-breeding sites during their entire lives. If a Black-tailed Godwit is on a patch of mud in December one year then it will be back there the next year, and possibly for the next twenty.

blog RedshankThere is no reason to believe that Black-tailed Godwits are unique in being site-faithful. In the WaderTales blog called A place to roost there is a description of the consequences of site removal for Redshank in Cardiff Bay. Birds displaced by the flooding of the bay had much lower survival rates in the next year and in subsequent years than other Redshank with which they shared their new winter homes. This illustrates the second point; even though these Redshank were only forced to move a few kilometres, they were still severely disadvantaged.

Limosa Black-tailed Godwits

The Tagus really comes into its own during the late winter, as limosa Black-tailed Godwits pour into the area, en route to their breeding grounds in continental Europe. An increasing number of the limosa subspecies now spend the winter on the estuary and in surrounding fields but numbers grow rapidly in January, as others join them from sites as far south as Guinea, in West Africa. On the Tagus, they moult into summer plumage and build up fat reserves that will fuel flights to The Netherlands and surrounding countries, and prepare them for the breeding season that lies ahead. A favourite rice field may hold up to 70,000 Black-tailed Godwits in late February, which includes half of what’s now left of the Dutch breeding population. This is also where many of the birds that are heading back to the Nene and Ouse Washes of Eastern England fuel up for the final leg of their journeys home. Several of the Project Godwit head-started birds (youngsters raised from eggs and released when just about to fledge) have been seen on the Tagus in February.

blog flock ground

To watch vast feeding flocks of Black-tailed Godwits, or their swirling aerial displays, when disturbed by a hunting Peregrine, is an amazing experience – a highlight for locals and for visiting birdwatchers, who holiday here in late winter and early spring. It’s especially impressive to watch the godwits at dusk, when clouds of Glossy Ibis create a backdrop to the action, as they move off the fields and cross the IBA to roosting islands on the far side of the estuary.

blog take offAs indicated earlier, The Tagus Estuary is designated as an EU Special Protection Area because of its crucial role in the lives of a suite of species, just one of which is the Black-tailed Godwit. Over the last few years, the average peak godwit numbers on the Tagus and Sado Estuaries in Portugal have risen from 44,000 to 51,000, at the same time as the breeding population of the subspecies has dropped rapidly (see this WaderTales blog about 75% drop in Dutch numbers). The Portuguese increase has coincided with a rapid decline in spring totals in Extremadura (Spain).

Without colour-rings, it might be assumed that individual Black-tailed Godwits have changed their migration routes, suggesting a flexible response to changing conditions. This is not the case. In their paper, Generational shift in spring staging site use by a long-distance migratory bird, Mo Verhoeven and colleagues show that nearly all of the older birds stick to the routes that they know, with young birds establishing routes that are more likely to include the Tagus and Sado Estuaries. Western Portugal has become vitally important to limosa Black-tailed Godwits, a subspecies that is in huge trouble and upon which millions of conservation Euros are being spent in The Netherlands and elsewhere.

blog godwits in air

What next?

The Portuguese Environmental Agency (Governmental institution) has given the go-ahead for the development of the airport at Montijo, despite robust arguments from researchers and conservationists about the inevitable effects on the IBA, and errors and limitations they have identified within the Environmental Assessment Study. There are also concerns about flooding risk, air pollution and other issues that seem not to have been fully assessed.

AEWASPEA, the Portuguese BirdLife partner, together with wader researchers who have studied waterbirds in the Tagus for decades, have submitted a request to the UNEP African-Eurasian Migratory Waterbirds Agreement (AEWA) to open an Implementation Review Process, to help Portugal to ensure that it complies with its obligations as a signatory to the treaty. The approach to AEWA is particularly appropriate for Black-tailed Godwits, as AEWA has already published a Single Species Action Plan to try to support efforts to restore populations of the rapidly declining limosa subspecies.

Black-tailed Godwits may be the most numerous of the key waterbird species for which the Tagus/Tejo Estuary is designated but let’s not forget the next most numerous six: 12,000 Dunlin, 6000 Avocet, 4500 Wigeon, 3300 Greylag Geese, 2000 Grey Plover and 1600 Greater Flamingos.

flamingo and ibis

Key conservation point

The most important conservation fact to bear in mind is that, as has been shown for Black-tailed Godwits, individual birds tend to be remarkably inflexible. Circumstances determine the migration pattern in the first year of life and, if a bird survives, it will continue to do the same things in subsequent years. Building an airport and then trying to reduce plane/bird interactions will quite probably affect the quality of the IBA for waders and other species. Individuals are unlikely to move elsewhere; they are more likely just to try to cope with altered circumstances. Habitat loss and disturbance on this scale are very likely to result in high levels of mortality and declines in the numbers of birds using this critically important site on the East Atlantic Flyway.

Petition

The Black-tailed Godwit is the Dutch national bird. The BirdLife partner in the Netherlands, Vogelbescherming, has launched a petition to register Europe-wide concern about the Portuguese decision to build the new airport. Not only will the new airport be a disaster for the East Atlantic Flyway, it also sets a precedent for developments affecting other Europe wetlands. Please click here to sign.

blog flock ground


GFA in Iceland

Graham (@grahamfappleton) has studied waders for over 40 years and is currently involved in wader research in the UK and in Iceland.  He was Director of Communications at The British Trust for Ornithology until 2013 and is now a freelance writer and broadcaster.

Sixty years of Wash waders

wwrg tt balance

Weighing a Turnstone

The Wash Wader Ringing Group (WWRG) started with a bang on 18 August 1959, when the team made a catch of 1,132 birds in a Wildfowl Trust rocket-net at Terrington, in Norfolk. Over the years, cannon have replaced rockets, catches have become generally smaller and the scientific priorities have been refined, but the Group continues to focus upon discovering more about the waders that use the Wash. This blog attempts to summarises what has been learnt about the waders that rely upon the Wash, the vast muddy estuary that lies between Lincolnshire and Norfolk, on the east coast of England.

Sixty years ago, the first goal was to understand where the vast flocks of waders that visit the Wash came from – a task that would provide great insights into the way that the whole East Atlantic Flyway works. In this time, over 300,000 birds have been caught and ringed on the Wash, as you can see in the table below. Equally importantly, hundreds of bird-ringers from across the UK and scores of visitors from around the world have joined WWRG teams, in order to learn more about the study of shorebirds. Further international collaboration has been fostered through overseas visits by WWRG members and emigration of some key personnel. The impact of the Group is truly global, as you can read in the WWRG report for 2014/2015.

wwrg table

A total of 307,226 birds is impressive, especially when some of the species totals are compared to the national totals of the BTO Ringing Scheme for the whole of Britain & Ireland since 1909. WWRG is responsible for over 40% of the Grey Plover, Knot, Sanderling and Bar-tailed Godwit, with Grey Plover topping the list at nearly 60%. These are terrific achievements for a group of volunteers. I don’t have the figures but I reckon that Nigel Clark has been responsible for the largest number of catches.

Wee quiz: What’s the best match between these Wash waders and the countries that they are quite likely to have come from? Answers at the end of the blog:

  • Species: Bar-tailed Godwit, Black-tailed Godwit, Curlew, Oystercatcher, Sanderling, Turnstone
  • Countries: Canada, Greenland, Iceland, Norway, Finland & Russia
wwrg box

Firing box connected to 4 cannon-nets

In the early days, rocket nets were borrowed from the Wildfowl Trust for an annual summer week of catches, but the development of cannon-nets gave opportunities for all-year ringing. The intensity of the Group’s activities grew in the 1970s, when there was a threat to build a freshwater reservoir on the mudflats. For a couple of years, Clive Minton (founder and leader) persuaded us to visit fortnightly, so that we could get better data on weight-gain and turn-over, using a mixture of cannon-netting and mist-netting. Everything we knew was published by the Group as The Wash Feasibility Study in 1975. These days, the Group gets together about ten times a year for catching and colour-ring-reading sessions.

wwrg oldies

By catching and ringing large numbers of the key species that visit the Wash, the Group was able to generate maps showing what are now well-known patterns of migration (see Which wader, when and why?). Early on in the Group’s history, there was a focus on nine species, with Black-tailed Godwit added as a tenth when numbers increased. Each of these species has its own section below. The maps were prepared for the Wash Wader Ringing Group 2016/2017 Report by Ryan Burrell, using data stored within the BTO archives. Blue dots represent WWRG-ringed birds that have been found abroad. Red triangles represent foreign-ringed birds caught on the Wash. The base maps used are by courtesy of Natural Earth (www.naturalearthdata.com).

Oystercatcher

wwrg map OCThe map alongside clearly demonstrates the strong link between the Wash and Norway. Other interesting things that have been discovered about Oystercatchers:

  • They live a long time. An Oystercatcher that we caught at Friskney on 30 July 1976 broke the longevity record for a BTO-ringed wader when it was shot in France on 4 April 2017 (41 years 1 month and 5 days). It was ringed as an adult so we don’t know the exact age – but it must have been at least 43 years old. There’s a WaderTales blog with a list of longevity records for BTO-ringed waders.
  • When life gets tough, Oystercatchers fail to complete their autumn moult, retaining some of their outer primaries for an extra year. The ability to complete moult and annual survival rates are both affected by cockle and mussel supplies on the Wash. There’s more about this in two papers in Biological Conservation and the Journal of Applied Ecology.

Grey Plover

wwrg GV GVIn the early days of the WWRG, Grey Plovers occurred in much smaller numbers than they do now. Writing in an article about the first 40 years of the Group, Clive Minton told the story of the first catch of 100, made in 1963, that was celebrated with three bottles of champagne provided by the late Hugh Boyd, delivering on an incentive that he had promised.

  • Over half of the Grey Plover that have been ringed in Britain & Ireland since 1909 have been ringed by WWRG since 1959 (58.9%)
  • All of the Grey Plover using the Wash breed in Siberia. Some birds spend the winter on the Wash but there are autumn moulting flocks of birds that will go on to winter in other parts of Britain & Ireland, and spring and autumn passage of birds that travel as far south as West Africa.
  • Grey Plover are late to leave the Wash, with the last departures not occurring until the start of June. Unsurprisingly, they are some of the last waders to return at the end of summer, which puts pressure on birds to finish moult before the short, cold days of winter. Some adults fail to complete primary moult, especially if food supplies are low. There is more about Grey Plover moult in this WaderTales blog.

wwrg map GV KN

Knot

wash knot

First-winter Knot (subterminal bands on wing coverts and, as yet, unmoulted juvenile fethers on upper-parts)

Knot (or Red Knot) are truly international waders, as is shown in this map of movements of islandica  (and a few canutus) birds  to and from the Wash. Several WWRG members have been heavily involved in efforts to understand the decline in numbers of the rufa subspecies in Delaware Bay (on the North American eastern seaboard) and Clive Minton has been at the heart of efforts to explain the sudden drop in survival of piersmai and rogersi adults that winter in Australia and migrate to Arctic Russia via the Yellow Sea (see Wader declines in the shrinking Yellow Sea).

  • We are still learning about Knot migration. The cluster of reports of WWRG-ringed birds in Northern Norway looks odd on this map projection but it turns out that this is a well-used stopping-off point for islandica Knot heading for northern Greenland and NE Canada. This route was first confirmed in 1985, when a joint Durham University and Tromsø University expedition caught 18 Wash-ringed birds in a total catch of 1703 birds.
  • The dot in Siberia looks odd but isn’t. This will be a bird of the canutus race, small numbers of which pause on the Wash in autumn and spring, on their way between the Russian Arctic and west Africa.
  • wwrg net set

    Setting cannon-nets

    Many birdwatchers visit the Wash in autumn and winter to see the swirling Knot flocks at Snettisham and Holme. If high tide is at first light, Knot and other waders sometimes roost on Heacham Beach, giving the occasional opportunity to make a significant catch. The most recent of these, on 11 February in 2012, included 2757 Knot, 77 of which were already wearing rings.

  • The most recent analysis of wader populations in Great Britain showed that there was a drop of nearly 20% in wintering Knot numbers (from 320k to 260k) in less than a decade (see Do population estimates matter?). Regular catches on the Wash will help produce estimates of annual survival rates and age ratios of the islandica subspecies.

Sanderling

wwrg sanderlingThe biggest catches of Sanderling are generally in the summer, when the Wash is a meeting point for birds from Greenland and Siberia. July can sometimes see catches of 200 or more birds. Traditionally, a Sanderling catch was the curtain-raiser at the start of Wash Week, an opportunity for the whole team to make one catch before splitting into ‘Terrington’ and ‘Lincolnshire’ teams for the rest of the main summer trip.

  • Wintering Sanderling on the Wash are thought to be exclusively of the race that heads northwest in the spring, to Greenland via Iceland.
  • Late summer and spring see the addition of birds passing through on their way from/to Siberian and Greenlandic breeding areas.
  • I well remember the first time we caught a Sanderling (on 26 July 1975) wearing an Italian ring (caught in Italy 9 May 1975). Thanks to Jeroen Reneerkens (whose work will be covered in an upcoming blog) I now understand that this is probably a bird that migrates from Namibia to Greenland in spring, via the Mediterranean. It will have been on its way back to Namibia when caught in July.

wwrg map SS DN

Dunlin

wash dunlin

Sam Franks, looking for the buffy tips on inner coverts, which distinguish first-year birds from adults

Nearly half of the waders caught by WWRG have been Dunlin – a total of 140,168 up until the end of 2018. There were really big flocks of Dunlin in the 1970s but numbers have dropped over the years, with peak counts now half what they were, according to WeBS data.

  • We caught over 3,500 Dunlin in one week in 1976 but the annual total has exceeded 1,000 in only four of the last ten years. Partly, this reflects a change in behaviour in the summertime, with fewer waders roosting on fields and hence less catchable.
  • Three races of Dunlin visit the UK. Our winter birds are alpina, from Siberia, NW Russia and northern Scandinavia. A lot of July birds are schinzii, breeding in the UK and as far north as Greenland, and we occasionally try to convince ourselves that we have caught an arctica from northern Greenland.
  • Data collected for the WeBS survey suggest that national winter totals have dropped by over 40% in 25 years. This could perhaps partly be explained by a redistribution of alpina, with new generations of young birds settling in wintering areas on the other side of the North Sea. Warmer winters may well make this a more practical proposition than in the 1970s. There’s more about this in this paper.

Black-tailed Godwit

wash blackwit

Newly ringed Black-tailed Godwit, caught in a mist-net at night.

Black-tailed Godwits became a priority species in 1995, when Jennifer Gill (University of East Anglia) started a project to study the movements of individuals, using colour-rings. Nearly 25 years later, the WWRG-ringed Black-tailed Godwits have contributed data to numerous papers, largely focusing upon migration.

  • The Wash is a hugely important area for moulting islandica Black-tailed Godwits. Some birds stay in East Anglia for the winter but others move south and west within the UK, west to Ireland and south to France, Portugal and Spain.
  • There are several blogs about Black-tailed Godwits in this WaderTales contents list.

Bar-tailed Godwit

One of the key things that was learned from the sudden decline in annual survival rates in a range of species that use the Yellow Sea (as mentioned above) is a need for regular monitoring of marked birds. The WWRG’s Scientific Committee set up colour-flagging projects for Bar-tailed Godwit, Curlew and Grey Plover, in order to increase the reliability of estimates of annual survival for three species that the Group does not catch in sufficient numbers to generate good retrap histories. Birdwatchers can help by reporting colour-marked birds here.

wwrg barwit map etc

  • In Bar-tailed Godwits: Migration & Survival there is a comparison of the data generated by a catch of 505 Bar-tailed Godwits in 1976 with the information that has been generated recently, using colour-flags.
  • Bar-tailed Godwits are long-lived birds. A WWRG bird holds the current record for a BTO-ringed Bar-tailed Godwit: 33 years and 11 months between ringing in 1978 and recapture in 2008. BTO longevity records are discussed in this WaderTales blog.
  • Colour-ring reading is now a significant element of Group activities, as described by Rob Pell in the WWRG Report for 2016/2017.

Curlew

Back in the 1970s, Curlew were still hunted on the Wash (paté made from autumn-shot birds was reported to be very tasty). Shooting stopped in Great Britain in 1981, when the maximum winter count on the Wash had dropped to about 3,000 birds, and by 2003/04 the maximum winter count was 15,336. Since then, numbers have declined, in line with national and international trends.

wwrg curlew map etc

  • A large number of Curlew on the Wash in winter are from Finland and surrounding countries. Surprisingly few are of UK origin.
  • Birds wearing WWRG leg-flags have been observed breeding in the Brecks (Norfolk/Suffolk).
  • The Curlew is internationally designated as ‘Near Threatened’. Is this really true when we can still see a field with 1000 roosting Curlew in Norfolk? Answers here.

Redshank

wash redshThe latest population estimates suggest that Great Britain has lost 26,000 wintering Redshank in less than a decade, representing a drop of 20%. Perhaps WWRG data can be used to help to explain these declines? Here are some of the things we know:

  • The Redshank on The Wash in the winter are mainly a mixture of birds from around the Wash, across the UK and from Iceland.
  • In cold winters, Redshank wintering on the Wash die in large numbers. After a period of severe weather in 1991, nearly 3,000 wader corpses were collected from along the tide-line, about 50% of which were Redshank. The winter WeBS counts for Redshank dropped by 50% after this mortality event but have recovered somewhat since then.
  • An analysis of nearly 1,000 dead Redshank showed that about two-thirds were of Icelandic origin. There was a tendency for smaller birds to be more susceptible to cold weather mortality than larger birds of the same species (More information in this paper by Jacquie Clark)

wwrg map RK TT

Turnstone

wash ttWinter Turnstone are birds that will head for Greenland and NE Canada in the spring but recoveries of birds in Finland and other Scandinavian countries indicate a passage of continental birds. African recoveries of WWRG-ringed birds probably include birds from Canada/Greenland and Finland/Scandinavia.

  • Turnstone wearing US Fish & Wildlife Service rings are occasionally caught on the Wash. Some of these rings were put on by Guy Morrison and his colleagues in Alert, Ellesmere Island, Canada. Guy was an early member of WWRG. It’s a small world!
  • The first Wash Turnstone were colour-ringed in 1999, as part of a study to understand why birds were feeding on the docks at Sutton Bridge. There is a WaderTales blog about the resulting paper by Jen Smart and Jennifer Gill. Colour-ringing continues, to measure annual survival rates.
  • Turnstone have a reputation for eating almost anything (including dog excrement and a human corpse) so do not be surprised if you see a colour-ringed bird scavenging for chips on the Hunstanton sea-front.

A few more highlights

Ringed Plover: this is not one of the ten key study species but 1,432 have been ringed between 1959 and 2018. Some birds are local breeders that hardly move anywhere but other birds link the Wash with Greenland, northern Norway, Morocco and Senegal.

wwrg GKGreenshank: The Group supports a colour-ringing project that was initiated by Pete Potts, in Hampshire. More information here.

Spotted Redshank: During the period 1959 to 2018, WWRG ringed a total of 85 Spotted Redshank, representing over 20% of the total ringed in Britain and Ireland since 1909. Amazingly, sixty of these birds were ringed on the same day – 27 July 1975. There is a blog about this catch and the recent decline in the number of Spotted Redshank visiting the UK. Fewer Spotted Redshanks.

Ruff: Until its closure, WWRG members spent many a smelly night at Wisbech Sewage Farm. This was a great place to catch Ruff, Curlew Sandpipers, Green Sandpipers etc. in mist-nets. Group members wrote a paper about Ruff moult and migration.

Rares: Occasionally there are surprises! WWRG has caught one each of Stone Curlew, Pectoral Sandpiper, Broad-billed Sandpiper and Terek Sandpiper. The last bird features in this WWRG blog.

What do we know now?

Migration studies have revealed the importance of the Wash to half a million or more waders each year – birds that spend the whole winter, others that refuel in the spring and vast numbers that rely on the food supplies in the mud to provide the energy for the post-breeding moult. There’s a selection of papers that have included WWRG data here, on the Group’s web-site.

wwrg cr TTThe Group still aims to maintain its general ringing programme, so that a representative sample of the key species carry rings. Colour-ringing projects aim to provide survival estimates for Curlew, Bar-tailed Godwit, Grey Plover and Turnstone, with Greenshank and Black-tailed Godwit colour-rings contributing to migration studies. Birdwatchers who visit the Wash can help by reporting colour-marked birds here, on the WWRG web-site.

WWRG data have been used to help inform decisions about the future of the Wash but the threats keep coming. Studies of migration and seasonal turn-over in numbers contributed hugely to decisions to provide national and international protection to the area and to fend off the 1970s plan to build a freshwater reservoir on the rich mudflats. The information that has been generated by many generations of volunteers over a period of sixty years has been used to manage the level of shellfish exploitation, to inform decisions about wind turbine locations and to manage activities that can cause disturbance.

The Wash Wader Ringing Group is very keen for its data to be used – and not just for impact assessment studies. Click here to learn more.

Diamond Jubilee

PLI

Phil Ireland releasing a Curlew

Over one thousand people are estimated to have contributed to sixty years of the Wash Wader Ringing Group’s activities. We have lived in barns, rolled cars, dug tens of thousands of holes, carried nets for miles, made important catches, had depressing failures, got frostbite, been threatened by surge tides and made friends for life.

In the whole of this period, there have been only two leaders of the Group – Clive Minton* (1959-1981) and Phil Ireland (1981-present). Bird ringers, wader biologists and millions of waders owe them both a huge debt of gratitude.

You can read more about the history of WWRG on the Group’s website:

*Clive Minton died in a car crash a few months after this blog was written. Friends and colleagues have shared some wonderful memories on the IWSG website.

wwrg sunset

Photo at the top of this blog is by Cathy Ryden. Many thanks to her and to other photographers.

Wee quiz:

  • Bar-tailed Godwit – Russia
  • Black-tailed Godwit – Iceland
  • Curlew – Finland
  • Oystercatcher – Norway
  • Sanderling – Greenland
  • Turnstone – Canada

 


GFA in Iceland

Graham (@grahamfappleton) has studied waders for over 40 years and is currently involved in wader research in the UK and in Iceland.  He was Director of Communications at The British Trust for Ornithology until 2013 and is now a freelance writer and broadcaster.

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Generational change

blog TGG on postIn a changing world, with more chaotic weather patterns and rapidly altering habitats, migratory birds are faced with opportunities and challenges. Long-term monitoring of colour-ringed Black-tailed Godwits, during a period of range expansion and phenological change, has revealed that individuals behave consistently over time but that the behaviour of new generations is moulded by the conditions they encounter.

A changing world 

When trying to explain observed changes in the distributions and annual cycles of migratory birds, there are many things to consider:

  • blog VM y flag

    Colour-rings enable life-time tracking. This bird, caught on its nest, had been ringed as a chick.

    Are individual birds able to take advantage of new breeding and non-breeding sites, as they become available, particularly if other areas become less suitable?

  • Are individuals able to change the timings and patterns of migration?
  • Do individuals adjust their migration routes as a consequence of changes in stop-over or wintering areas?
  • If individuals do not change what they do, how do we explain range expansions and changes in timing of migration?

Put simply, how does climate change lead to changes in distribution of migratory birds? Answering this question is key to being able to predict the rate and direction of future changes, and to assess whether our existing networks of protected sites will continue to support populations in the way that was intended. This issue was tackled by Jennifer Gill, José Alves and Tómas Gunnarsson in their paper “Mechanisms driving phenological and range change in migratory species”, published in Linking behaviour to dynamics of population and communities: applications of novel approaches in behavioural ecology and conservation, a special issue of Philosophical Transactions B (Royal Society).

Potential models

Change could happen in two main ways:

  • Individuals could relocate – having knowledge of a range of available conditions, they can choose to move elsewhere.
  • New generations could settle in new areas (in the breeding season, the non-breeding season or both) and/or adopt new migratory strategies.
blog map

Map that illustrates range expansion

Working out whether change happens through individual movement or generational shifts can only be done by life-long tracking of individuals, in populations in which range change is happening. The Icelandic population of Black-tailed Godwit is ideal for such an investigation. Black-tailed Godwits have been expanding into new breeding areas of Iceland for over 100 years, as discussed in this WaderTales blog. Population growth has been facilitated through warming spring conditions, as discussed in From local warming to range expansion.

blog TGG juvs

Naive youngsters, gathering together before migration

Icelandic Black-tailed Godwits fly south in the autumn, to spend the winter in the British Isles, The Netherlands, Belgium, France, Spain and Portugal. As numbers have grown, winter counts have increased in many areas, with new flocks appearing and expanding on estuaries and areas of wet grassland where the species was previously absent or scarce.

 

Winter distribution

The Wetland Bird Survey shows that there are three times as many Black-tailed Godwits wintering in Great Britain as there were 25 years ago. The biggest changes in numbers have occurred on estuaries in the northwest of England, with the Morecambe Bay winter maximum rising from about 180 to 3200, for instance. Where have these extra birds come from?

blog juvs on Axe

These young birds happen to have ended up on the Axe Estuary in Somerset

Black-tailed Godwits have been ringed in Iceland for nearly twenty years, providing a pool of known-age adults for which natal sites are known. Winter observations of colour-ringed individuals have shown an interesting pattern; birds breeding in newly-colonised areas, particularly in north and east Iceland, are the ones that are more likely to be found in newer winter sites.

In their paper, the authors suggest that birds nesting in these colder areas, where spring comes later, will be fledging quite late and leaving Iceland after adults have departed. With no experienced birds to follow, these young birds may well stop off at the first suitable site, many of which are in the north of the wintering range, and then they return to breed in their natal sites. Birds in Morecambe Bay don’t know that days are longer and the weather is kinder for other birds that travel further south to wintering areas such as Portugal.

blog RS Dee

Wintering birds in Northwest England

Observations from birdwatchers show that the same colour-ringed individuals are nearly always found at the same wintering sites each year. Whatever mechanism is producing this new-breeding-site to new-wintering-site link, it is becoming clear that older birds continue to do what they have always done, with changes in distribution happening as a result of a generational shift.

The annual cycle

Colour-ringed Black-tailed Godwits have been tracked for over 25 years, with a small number of individuals contributing data for the whole of this period. This tracking information can be used to ask how much individuals move around and experience different sites and to assess whether individuals from different generations are using different parts of the range.

Using colour-rings, the Black-tailed Godwit team has discovered that, although individuals can live for over 20 years, in that time they generally use a total of only about four sites between leaving Iceland in late summer and returning in the spring. Basically, individual birds have very limited experience of sites and there is no evidence that they have moved to occupy different sites as, for instance, winter conditions have changed.

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Spring arrivals in Iceland

Colour-ring observations have shown that individual birds do not change their breeding or wintering locations and that migrating individuals often appear in the same stop-over sites year after year. The timing of movements is also pretty consistent, especially in the spring. A previous WaderTales blog called Why is spring migration getting earlier? demonstrated that the timing of  migration of individual Black-tailed Godwits varies very little, with observed shifts in the period of migration being driven by young birds returning to Iceland for the first time on average doing so somewhat earlier than previous generations. Once individual birds settle into a timing pattern, they stick to it.

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Black-tailed Godwits, newly arrived in Iceland after crossing the Atlantic

Migration patterns

As discussed above, individual Icelandic Black-tailed Godwits have experience of only a small number of sites, which they use on an annual cycle. When migrating, a bird will generally use the same stop-over site when breaking its journey south, to undertake autumn moult, or on their way north, to take on fat for the trans-Atlantic journey. There is a range of spring migratory strategies in islandica Black-tailed Godwits, as discussed in Overtaking on migration.

blog wwrwOnce established, the annual migratory programmes of individuals rarely change, as illustrated by the map to the right. Colour-ringed Black-tailed Godwit W-WR/W regularly moulted on the Wash, in eastern England, before spending the late winter and spring in northwest England. In the late summer of 2002 he was reported at Slimbridge on 18th and 20th July but back on the Wash on the 25th. Having made the Atlantic crossing and ended up in southwest England, he was able to correct what he may have perceived to be his mistake, returning to the moulting area that he had been using since at least 1996.

Individuals might not change their annual migration routes but we do see changes in numbers on different sites that are used during migratory stop-overs. In a paper published in 2018, Mo Verhoeven and colleagues investigated whether observed changes in migratory patterns of a population of the limosa subspecies of Black-tailed Godwit were caused by individuals altering their strategies or by generational change.

Limosa Black-tailed Godwits leave breeding areas in countries such as The Netherlands in late summer, heading south to either West Africa or Iberia, where they spend the winter. In spring they all gather in staging sites in Portugal and Spain, typically on rice fields. Over the course of less than ten years, the average peak number in Extremadura (Spain) has dropped from about 24,000 to 10,000, while the numbers on the Tagus and Sado estuaries rose from 44,000 to 51,000. These changes took place during a period of rapid population decline, as described in this blog focusing on a paper by Rosemarie Kentie and colleagues.

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Limosa Black-tailed Godwits feeding in a rice field in the Tagus estuary

Mo Verhoeven et al have shown that this rapid population-level shift in spring stop-over sites from Spain to Portugal, 300 km further west, was driven by young godwits increasingly using Portugal in the period January to March, instead of Spain. Nearly all of the older birds stuck with the routes they knew. The paper is Generational shift in spring staging site use by a long-distance migratory bird.

Change happens to birds

One thing that is becoming clear in Black-tailed Godwits is that birds are being affected by change – individuals do not have the knowledge or flexibility to effect change. Even in long-lived birds, like Black-tailed Godwits, we see no evidence of individuals altering what they do over what is now two decades, despite the fact that the species’ migration dates, wintering areas and migration routes have all perceptibly changed over the same time period. It’s all about generational change. The behaviour patterns of young birds arise from the conditions they encounter in the first year of life, after which they are repeated.

Details of the Generational Change paper by Gill et al

blog LJ sum plumThe paper at the heart of this blog is: Mechanisms driving phenological and range change in migratory species by Jennifer Gill, José Alves and Tómas Gunnarsson, from the Universities of East Anglia (UK), Aveiro (Portugal) and Iceland. It is published in Linking behaviour to dynamics of population and communities: applications of novel approaches in behavioural ecology and conservation, a special issue of Philosophical Transactions B (Royal Society).

The paper could not have been produced without the help of “thousands of observers of colour-ringed godwits who have made these analyses possible”. This WaderTales blog is a celebration of the work they do: Godwits and Godwiteers.


GFA in Iceland

WaderTales blogs are written by Graham Appleton, to celebrate waders and wader research.  Many of the articles are based on previously published papers, with the aim of making wader science available to a broader audience.

@grahamfappleton

 

Ireland’s wintering waders

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There’s still space for a few Knot

The island of Ireland is a great refuge for wintering waders, washed as it is by the warm waters of the Gulf Stream. It’s just a quick hop across the Atlantic from Iceland for Black-tailed Godwits, Golden Plovers, Redshanks and Oystercatchers. For birds travelling from Siberia, such as Bar-tailed Godwits and Grey Plovers, it’s a longer journey but one that’s well worth making.

If Ireland is such a great destination for shorebirds, why do the latest population estimates reveal a decline of nearly 20% in wader numbers in just five years?

This blog summarises the wader information, published in Estimates of waterbird numbers wintering in Ireland, 2011/12 – 2015/16 in Irish Birds. The totals in the report are split into counts for the Republic of Ireland and Northern Ireland but, given that waders don’t recognise borders, most of the comments in this blog relate to the whole of Ireland. The results for 2011-16 have been compared to the equivalent figures for 2006-11 and set in the context of the totals of wintering waders throughout the East Atlantic flyway, as combined by Wetlands International. The Irish data were collected by the amazing volunteers who make monthly, winter counts for I-WeBS (BirdWatch Ireland & National Parks & Wildlife Service) and WeBS (BTO/RSPB/JNCC in Northern Ireland).

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Headline figures

Fifteen species are considered in this report. The most numerous are Lapwing and Golden Plover, which account for an estimate over 170,000 individuals between them, whilst the smallest contributions are made by Purple Sandpiper (662) and Greenshank (1317). In total, the average estimated number of waders in the winters during the period 2011-16 is 429,170 birds but it should be noted that this total excludes two widespread and common species – Woodcock and Snipe – as well as the enigmatic Jack Snipe. To update previous estimates for these three species, which were last made using distribution and abundance data collected during Bird Atlas 2007-11 fieldwork, it would be necessary to run a special inland survey. There is also some question about Lapwing and Golden Plover numbers, simply because so many of these birds are found in areas that are not covered by monthly waterbird counts.

Biggest changes

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The Irish Sanderling population has increased by 13.2% in five years

The combined average winter maximum count of the 15 wader species examined in the report declined by 102,310 birds (19%) in the five-year period between 2006-11 and 2011-16. This is extremely worrying. If Lapwing and Golden Plover are excluded from consideration, as there is uncertainty about the completeness of counts, there are five species that are of particular concern; Knot numbers dropped by more than 40% and Oystercatcher, Dunlin, Redshank and Turnstone numbers by more than 20%. The Purple Sandpiper population estimate dropped by over 30% but relatively small numbers of this species are encountered around the rocky coast of Ireland. The only species to show increases were Sanderling, Bar-tailed Godwit, Black-tailed Godwit and Greenshank.

In a previous WaderTales blog, there is detailed information about population estimates for Great Britain: Do population estimates matter? In Great Britain there were similar rates of decline for Redshank and Turnstone (measured over an eight-year, rather than five-year period) but much smaller falls for Knot, Oystercatcher and Dunlin. The possible causes of the changes in Ireland are discussed in the paper in Irish Birds. They include flyway-scale declines (e.g. Knot and Curlew) and the possibility that more birds from the east are now wintering on the coasts of mainland Europe (e.g. Dunlin and Grey Plover).

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European context

Blog tableThe table alongside gives an indication of the relative importance of Ireland, Great Britain and, together, the British Isles to the birds that use the East Atlantic flyway during the winter period. The three columns show the percentage of each species found in each of the three regions. Summarised international counts, as used in the paper, were kindly provided by Wetlands International. In the case of four species, Ireland is host to a significant proportion of the Icelandic breeding population (Oystercatcher, Golden Plover, Black-tailed Godwit and Redshank).

Notes: As mentioned earlier, there are questions about the precision of estimates for Lapwing and Golden Plover, although the population trends are reliable. The Ringed Plover percentage seems high (98% for British Isles) but this may well reflect the fact that the Non-estuarine Waterbird Survey has uncovered significant numbers of the species on the open shores of Great Britain. These extra birds are included in the new totals for GB but not in the flyway total. The percentages for Black-tailed Godwit seem low, as discussed further down.

Ireland is particularly important for Golden Plover, Ringed Plover, Bar-tailed Godwit and Black-tailed Godwit, as well as for the Icelandic subspecies of Redshank. Greenshank is excluded because the percentages are below 1% of the flyway population for Ireland and for Great Britain.

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11% of Bar-tailed Godwit on the East Atlantic Flyway spend the winter in Ireland

Although there are important populations of breeding waders in Ireland, the shores and wet fields of the island really come into their own during July and August, when the first ‘winter’ waders arrive, and they only become quiet again in April and May, when the last birds head north and east to nest. A successful breeder is likely only to be away for four or five months, meaning that these waders will spend by far the largest part of the year in Ireland. The island is even more important for immature birds. Young Oystercatchers that arrive from Iceland, Scotland or perhaps Norway when just a few months old are likely to spend the next 30 months in Ireland before making their first trip north. There is a WaderTales migration blog about the Oystercatchers that fly from Iceland: Migratory decisions for Icelandic Oystercatchers.

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Curlew in the Republic

Curlew numbers in the Republic of Ireland illustrate the relative importance of the country for breeding and non-breeding populations. The winter population estimate for Curlew in the Republic is 28,300 but the most recent survey conducted by BirdWatch Ireland and NPWS, as summarised in the WaderTales blog Ireland’s Curlew Crisis, reveals that the number of breeding birds has crashed to just 138 pairs. Accounting for young Irish birds that have not started to breed, and even if we assume that all Irish birds stay in the country for the winter, then the total number of home-grown Curlew seen in non-breeding flocks is at most about 400. This means that every winter flock of 70 Curlew will contain an average of just one Irish bird. Far more deliver their curl-ew calls with a Scottish, Finnish or Swedish ‘accent’. The map below shows the migration pattern for Curlew ringed in or found in Britain & Ireland.

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Black-tailed Godwit

In the table above, it looks as if 18% of Iceland’s Black-tailed Godwits spend the winter in Ireland. This is probably an underestimate of the importance of the Republic of Ireland and Northern Ireland to the species. The flyway total for Black-tailed Godwit is given as between 98,000 and 134,000 in the Irish Birds paper and the percentage figure is based on 110,000. These three figures are almost certainly too high, as they build upon country-based estimates that have subsequently been revised. The true figure is likely to be around 60,000 to 65,000 (J. Gill pers. comm.), which would suggest that the maximum winter count in Ireland of 19,800 represents at least 30% of the islandica Black-tailed Godwits. Add in extra birds that moult in Ireland in the autumn, before moving further south to countries such as Portugal, and other birds that spend spring months on the island, and Ireland becomes even more important for Black-tailed Godwits!

blog BTMost birdwatchers might associate flocks of waders with estuaries but Black-tailed Godwit is an excellent example of a species that also relies on inland fields, either close to estuaries or along river valleys. Whilst undertaking PhD research on Black-tailed Godwits in south-east Ireland, Daniel Hayhow showed that there is insufficient time to find enough estuarine food during the mid-winter tidal cycles, with birds topping up their resources on grassland. You can read more about the energetic consequences of choosing to winter in eastern England, Portugal and Ireland in this blog: Overtaking on migration. Site designation and planning decisions need to take account of the grassland feeding requirements of Black-tailed Godwits and other waders that do not spend all of their time on estuaries, particularly Curlew.

Conservation implications

Some of the issues facing waders may be related to threats that species face in the breeding grounds. However, it may be easier to introduce measures that provide better protection and feeding opportunities in the wintering area, as ways of maintaining populations through the non-breeding season, than it is to deal with problems in the High Arctic. (Although we can all help by reducing carbon emissions, in order to minimise global warming, of course).

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Reading the report, I was reminded of the need to consider a range of conservation issues:

  • Care needs to be taken when considering shoreline developments. These can directly remove habitat or squeeze the width of the intertidal zone.
  • Increased harvesting of shellfish can affect species such as Oystercatcher and Knot and brings risks of introducing alien species and diseases.
  • In the drive to cut carbon emissions, tidal, wave and wind power developments need to be sited in appropriate places.
  • Off-shore harvesting of growing kelp beds has been suggested, as a way of producing fertiliser and biofuels. This process could reduce protection for beaches and change the availability of resources for species such as Turnstone and Sanderling.
  • Grassland areas need to be considered (and not just estuaries) when planning protection for species such as Curlew and Black-tailed Godwit.

blog RKPaper

Estimates of waterbird numbers wintering in Ireland, 2011/12 – 2015/16. Brian Burke, Lesley J. Lewis, Niamh Fitzgerald, Teresa Frost, Graham Austin, and T. David Tierney. Irish Birds No. 41, 1-12.

There is a complementary paper in British Birds, covering Great Britain. The wader information is summarised in this blog: Do population estimates matter?


GFA in Iceland

WaderTales blogs are written by Graham Appleton, to celebrate waders and wader research.  Many of the articles are based on previously published papers, with the aim of making wader science available to a broader audience.

@grahamfappleton

Do population estimates matter?

blog top godwitsThis month (March 2019) saw the publication of Population estimates of wintering waterbirds in Great Britain, which includes all the wader species from Little Stint to Curlew. Given that the Wetland Bird Survey already covers about 2000 wetlands and provides annual monitoring, why do we need to know the total number of birds in Great Britain?

I suggest four reasons:

  • If we count the number of Curlew and we have a figure for the European population then we know that Great Britain is responsible for nearly 20% of Europe’s Curlew each winter, thereby strengthening the case for national conservation action;
  • If we have a national figure, then we know that a flock of 2000 Black-tailed Godwit represents (as it turns out) over 5% of the British total, which is a useful criterion when assessing the conservation importance of individual sites;
  • blog GKPopulation totals help to put annual percentage changes into context;
  • And simply because people ask questions such as “how many Greenshank are there in the country during the winter?”

So, here’s the bottom line. In their 2019 review of waterbird numbers in British Birds, a team from BTO, WWT, JNCC & RSPB reveal that an estimated total of 4.9 million waders spend the winter in Great Britain. That’s about one third of all waders on the East Atlantic Flyway. Impressive!

Please note that Northern Ireland figures are included in an upcoming report for the island of Ireland.

Making the counts

The population estimates owe a lot to those who undertake monthly Wetland Bird Survey (WeBS) counts on estuaries, lakes and waterways, during the winter months, year in and year out. Counts from the period 2012/13 to 2016/17 are used in the population estimates that form the basis for the 2019 review. WeBS data have many other uses, as you can read here: Wetland Bird Survey: working for waders.

blog CUFor species of wader that also make use of the open coast, the Non-estuarine Waterbirds Survey of 2015/16 (or NEWS III) provided additional data, updating the NEWS II figures from 2006/07. The vast majority of our wintering Purple Sandpipers are found on open beaches and rocky shores, as well as large numbers of Turnstone, Ringed Plover and Sanderling, together with significant numbers of Oystercatcher, Curlew and Redshank. There’s more about NEWS in this slightly dated blog: NEWS and Oystercatchers for Christmas.

The last assessment of winter wader populations was made by the Avian Population Estimates Panel and published in British Birds in 2013 as Population estimates of birds in Great Britain and the United Kingdom (APEP3). In here, estimates for waders were largely based on WeBS data for the period 2004-09 and NEWS II. The new assessment is presented as Population estimates of wintering waterbirds in Great Britain and also published in British Birds. It uses WeBS information for the period 2012-17 and NEWS III data. Effectively, there is an 8-year or 9-year difference between the two sets of figures.

The biggest losers

blog graphicGreat Britain is extremely important in the context of the East Atlantic Flyway, as is obvious from the fact that the area holds nearly five million waders. The WeBs counts already monitor the ups and downs on an annual basis but this review provides an opportunity to turn the percentages into actual numbers. It is concerning that, over a period representing less than a decade, the average maximum winter count for six of the species that were surveyed dropped by a total of over 150,000. These big losers were Knot, Oystercatcher, Redshank, Curlew, Grey Plover and Dunlin, ordered by number of birds lost, with Knot seeing the biggest absolute decline.

In preparing the new estimates for the British Birds paper, an opportunity was taken to refine the way that populations are calculated, based on Use of environmental stratification to derive non-breeding population estimates of dispersed waterbirds in Great Britain, by Verónica Méndez et al. The new methodology explains some of the differences between percentage changes reported by WeBS and the percentage changes obtained by comparing the latest population estimates to those in APEP3.

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The Knot estimate dropped from 320,000 to 260,000. This figure is higher than might be expected from the counts that take place at sites covered by WeBS, being larger than the ten-year decline of 14% reported in the last WeBS report. Knot are mobile species within the North Sea and Atlantic Coast wintering area and it is possible that British losses may be explained, at least to some extent, by redistribution.

blog oyc graphThe drop in Oystercatcher numbers from 320,000 to 290,000 appears to be less than 10%, compared to a ten-year decline of 12% on WeBS. Improved analysis of NEWS data helped to add some more birds to the open-coast estimate so the 10% fall may underestimate the seriousness of the Oystercatcher situation. The 25-year Oystercatcher decline on WeBS is 26%, which is not surprising if you look at the changes to breeding numbers in Scotland, where most British birds are to be found. There’s more about this in: From shingle beach to roof-top.

blog RKThe Redshank decline of 26,000 is higher than would be predicted from WeBS figures, suggesting a drop of over 20% since APEP3, rather than ‘just’ 15% for the ten-year WeBS figure. This is a species that also features strongly in the Non-estuarine Waterbird Survey and that might explain the difference. Wintering Redshank are mostly of British and Icelandic origin, with the Breeding Bird Survey (BBS) suggesting a ten-year decline of 24% in our British breeding birds.

The Curlew is now globally recognised as near-threatened. The latest winter estimate is 120,000, down from 140,000 in APEP3. The new total represents between 14% and 19% of the European population, which means that we have a particular responsibility for this much-loved species. Only the Netherlands holds more wintering Curlew than Great Britain. Is the Curlew really nearly-threatened? is one of several blogs about Curlew in the WaderTales catalogue at www.wadertales.wordpress/about .

blog 2 DNIt has been suggested that the long-term declines of Grey Plover and Dunlin  may be associated with short-stopping, with new generations of both species wintering closer to their eastern breeding grounds than used to be the case. WeBS results indicate a 31% drop in Grey Plover and a 42% drop in Dunlin, over the last 25 years. There was a loss of 10,000 for both species between APEP3 and the new review, representing declines of 23% and 3% respectively.

The biggest winners

There are four big winners in the period between APEP3 (2004-09) and the new review (2012-16), although, even here, not all as it seems.

The Avocet has seen further dramatic gains. with the estimated wintering population rising to 8,700. The increase is not quite as big as might have been expected, based on the 43% rise seen in ten years of WeBS counts, but it is still a dramatic continuation of a 40-year trend.

The numbers of Bar-tailed Godwit and Ringed Plover are both substantially higher but at least a proportion of each of these changes is linked to the better coverage and more sophisticated sampling methods that were discussed earlier. Bar-tailed Godwit increases may also reflect redistribution around the North Sea.

blog BW graphOne of the consequences of improved statistical techniques, as used this time around, is the apparent decline in the estimated population of Black-tailed Godwit. The new figure of 39,000 is 4,000 smaller than in APEP3, despite the fact that the WeBS graph clearly shows an increase. Interpolation using WeBs figures suggests that the earlier population estimate should have been 31,000, rather than 43,000.

There are other winners too, as you can read in the paper. At the start, I posed the question “how many Greenshank are there in the country during the winter?”.  The answer is 810, representing an increase of 200 since APEP3.

Game species

The estimates for the three wintering waders that are still on the UK quarry list have not changed since APEP3 (published in 2011) as there are no new data available.

Golden Plover: The winter estimate remains as 400,000, as there has been no comprehensive, winter survey since 2006/7. Large numbers of Golden Plover arrive from Scandinavia, Europe and Iceland in the late summer, joining the British birds that choose not to migrate south or west. The GB breeding population is probably less than 50,000 pairs. Most breed in Scotland which has seen a breeding decline of 23% in the period 1995 to 2016 (BBS). Golden Plover is still ‘green listed’.

snipe-headerSnipe (Common): The winter estimate remains as 1,100,000 – a figure that was acknowledged in APEP3 as being less reliable than that of most species. At the same time, the GB breeding population was estimated as 76,000 pairs, indicating at least a 4:1 ratio of foreign to British birds, and that does not take account of the number of British birds that migrate south and west. Snipe are ‘amber listed’ but BBS suggests a recent increase of 26% (1995-2016). There is a WaderTales blog about  Snipe and Jack Snipe.

Woodcock: The winter estimate remains as 1,400,000 – another figure that is not considered to be particularly precise, with much variation between years. The diminishing breeding population is dwarfed by winter numbers, as you can read in this WaderTales blog, with increased attention being given to ways to afford better protection of red-listed, British-breeding birds.

January counts

blog BTThe paper in British Birds also includes a table of January population estimates, to provide data that are comparable to mid-winter counts in other countries. These figures are used in waterbird monitoring for the International Waterbird Census for the African Eurasian Flyway. The main table (and figures mentioned above) are average maximum winter counts (in the period September to March). Black-tailed Godwit is one species that illustrates the difference, with a mean of 30,000 in January and a mean peak count of 39,000. Having moulted in Great Britain, some Black-tailed Godwits move south to France and Portugal in late autumn, returning as early as February. January counts are therefore substantially lower than early-winter and late-winter counts. There is more about the migratory strategy employed by Black-tailed Godwits that winter in southern Europe in Overtaking on Migration.

Looking forward

blog BB coverThe authors have done a tremendous job. They have refined the way that estimates are calculated, they have combined the results from WeBS and NEWS III, and they have delivered population estimates for 25 wader species and many more other species of waterbirds. These population estimates will be used in conservation decision-making until the next set of numbers becomes available. Meanwhile, thousands of birdwatchers will count the birds on their WeBS patches in each winter month, every year. Without them, this paper could not have been written.

Before the next assessment, there will need to be another NEWS survey, to check up on species that use rocky and sandy shore birds, such as Purple Sandpipers, Turnstone and Curlew. Hopefully, there will also be a dedicated survey to assess Lapwing and Golden Plover numbers and perhaps we might find a way to refine the old estimates for Woodcock, Snipe and Jack Snipe.

Paper

Population estimates of wintering waterbirds in Great Britain. Teresa Frost, Graham Austin, Richard Hearn, Stephen McAvoy, Anna Robinson, David Stroud, Ian Woodward and Simon Wotton. Published in British Birds Volume 112. March 2019.

British Birds is a subscription journal. The issue containing this paper can be purchased separately. At some stage, the paper will become free-to-view.

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GFA in Iceland

WaderTales blogs are written by Graham Appleton, to celebrate waders and wader research.  Many of the articles are based on previously published papers, with the aim of making wader science available to a broader audience.

@grahamfappleton

From local warming to range expansion

blog adultOver the last century, Icelandic black-tailed godwits have increased 10-fold in numbers and their breeding range has expanded throughout lowland Iceland. Although changing climatic conditions seem likely to have enabled this process, what is the mechanism? How might warmer conditions have contributed to this growth? This blog is a summary of a paper by José Alves and colleagues in Ecology & Evolution.

Setting the scene

If scientists are going to try to predict species’ responses to future climatic conditions, they will need to understand the ecological, behavioural and historical factors that influence how change happens. In other words, what mechanisms can link changes in climate with changes in population size and distribution?

tableAppreciating how local climate effects can potentially scale up to population-level changes requires climate effects to be measured across a population. Iceland is a great place to study these processes as it has been getting warmer since at least 1845, as measured by one of the longest temperature time-series in the world. The country hosts internationally-important breeding populations of many migratory bird species, for which changing climatic conditions could have important implications, including Black-tailed Godwit. The data in the table alongside have been extracted from a report to AEWA that was discussed at the 12th Standing Committee in Jan/Feb 2017.

A booming population

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Expanding breeding range in Iceland

In the early 1900s, Black-tailed Godwits were restricted to the southern lowlands of Iceland but, since then, birds have gradually colonised coastal lowland areas throughout the country, with larger areas closer to occupied sites being colonised first (as described in this WaderTales blog). The population now numbers over 50,000 individuals, which is likely to represent an approximately 10-fold increase over the last century.

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Newly hatched chicks, still in their nest-cup, well hidden in grass

Icelandic godwits are long-lived migratory shorebirds with a typical lifespan of between 15 and 20 years. They nest in lowland wetlands dominated by grasses or by dwarf birch and sedges. They hide their nests, which means that they require sufficiently tall vegetation to conceal the nest and an incubating adult. Both vegetation growth and the timing of emergence of invertebrate prey for wader chicks are strongly temperature-dependent, particularly at high latitudes, which means that the timing of nesting and the growth-rate of chicks are likely to be influenced by local temperatures.

blog colonisationOver eight years, during which temperatures in Iceland varied substantially, José Alves and colleagues were able to quantify the influence of temperature on laying dates and the duration of the pre-fledging period of Icelandic godwits, and the subsequent influence of hatching dates on recruitment of chicks to the wintering or subsequent breeding population. The authors then used these relationships to model how the timing of breeding and the annual recruitment of juveniles into the breeding population may have contributed to population growth and the successful colonisation of new (and now warmer) parts of Iceland.

Catch your godwits

blog cr chickBlack-tailed Godwits are very good at hiding their nests and chicks! These three quotes from the paper help us to appreciate the effort that goes into establishing some of the key facts that underpin the modelling at the heart of this paper:

  • “Every nest was visited regularly and successful nests were revisited at the estimated hatching date, in order to capture and mark chicks and adults with individual combinations of colour-rings.”
  • “For each family, one of the adults was captured using either a nest-trap or a hand-held net-gun.”
  • “In 2012 and 2013, 32 godwit families were tracked during chick rearing, from hatching to fledging (n = 18) or brood loss (n = 14).”

Away from the main study area, volunteer ringers, led by Pete Potts of Farlington Ringing Group, caught, measured and colour-ringed chicks, thereby providing an assessment of hatching dates of chicks in other parts of Iceland.

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The assessment of which chicks subsequently survived and recruited into the adult population relied heavily upon the observations of hundreds of birdwatchers, throughout Western Europe, who take the time and trouble to report sightings of colour-ringed birds. Examples of their dedication and links to other papers that rely upon their efforts can be found in Godwits and Godwiteers.

Major Findings

Effect of temperature on timing of breeding season events: In Icelandic godwits, mean laying dates were approximately 11 days earlier in the warmest of years than in the coldest (two-degrees Celsius lower). This earlier start to the breeding season is thought to be linked to faster vegetation growth in warmer springs. The lengths of the chick pre-fledging period varied by only about 3.6 days between the warmest and coldest years but this additional difference means that fledging can happen a fortnight earlier in the warmest of years. 

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blog juv flocksProbability of recruitment: Early-hatched chicks are more likely to survive and recruit into the adult population, and the 11-day advance in hatch dates in warm years equates to an increase in absolute recruitment probability of about 10%. The additional benefits of more rapid chick growth and fledging in warmer years probably further increases this differential. In cold years, when most nests are laid late, very few chicks are likely to recruit to the adult population. For example, in 2011, the coldest year recorded during the study, only about 16% of 118 ringed chicks recruited into the wintering population. Early-fledged chicks presumably have more time to improve body condition prior to migration, there is an increased probability of travelling in adult-dominated migratory flocks (see graphic from Gunnarsson 2006), and earlier departure for wintering areas may allow more time in which to find a favourable wintering location.

blog big chickRegional variation: Traditional breeding sites are warmer, and so nests are likely to be earlier and incubation shorter, which means that more of the chicks from these areas are likely to survive and recruit into the population. The range expansion in this system could therefore have been driven by increased productivity and dispersal from traditionally colonised areas, supplemented by increased productivity within newly colonised – and now warmer – areas. Given the high levels of natal philopatry in Black-tailed Godwits (WaderTales blog about philopatry), the authors suggest that improved breeding conditions, following colonisation of new areas, have fuelled local population increases and further range expansion.

Are these findings applicable to other species?

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Sightings of colour-ringed juveniles, such as this one in eastern England, helped to establish recruitment rates.

The authors of this paper have been studying a species breeding at the northern limit of its range, in a country that has been subject to rapid climate change and in which there are relatively large differences in temperatures over quite small distances. This provides an ideal gradient over which to study change. Also, and unusually, it was possible to measure recruitment of chicks from right across Iceland, because of the colour-ring reports from observers. This set of circumstances have combined to enable the team to show that warming trends have the potential to fuel substantial increases in recruitment throughout Iceland, and thus to have contributed to local population growth and expansion across the breeding range. They propose that the same factors may be harder to tease apart for other species, in different environments, but that advances in lay dates and increased recruitment associated with early hatching may be key processes that drive population and range changes in migratory systems.

Paper

Linking warming effects on phenology, demography and range expansion in a migratory bird population. José A. Alves, Tómas G. Gunnarsson, William J. Sutherland, Peter M. Potts & Jennifer A. Gill.

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Juveniles gather together in the late summer, prior to departure


GFA in Iceland

Graham (@grahamfappleton) has studied waders for over 40 years and is currently involved in wader research in the UK and in Iceland.  He was Director of Communications at The British Trust for Ornithology until 2013 and is now a freelance writer and broadcaster.

 

Designing wader landscapes

blog whimbrelMuch has been written about the negative impacts of agriculture on breeding birds – but farming can be good for some species. In Iceland, where high-input agriculture is relatively recent, breeding waders are commonly found in nutrient-rich environments that are associated with increased production. How can high breeding densities of waders be maintained, as farming continues to expand and intensification increases?

In her paper in Agriculture, Ecosystems & Environment Lilja Jóhannesdóttir investigates the distribution of breeding waders across landscapes with varying amounts of highly-cultivated fields and semi-natural areas. She discovers that, in some circumstances and at an appropriate level, adding cultivated land within a broader mosaic of habitats may benefit breeding waders. Is this a model system that provides clues as to how to design landscapes that can support sustainable breeding wader populations in other parts of the world?

The waders of Iceland

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Breeding populations of waders in Iceland (AEWA report)

Iceland is a hot-spot for breeding waders, holding half or more of Europe’s Dunlin, Golden Plover and Whimbrel, in a country that is a bit smaller then England. The paper at the heart of this blog is written by Lilja Jóhannesdóttir, who worked with colleagues from the University of Iceland, the Agricultural University of Iceland, the University of East Anglia (UK) and the University of Aveiro (Portugal). They investigated how different ways of increasing agricultural productivity might impact upon these species, and others such as Black-tailed Godwit, Redshank and Snipe.

Much of Iceland’s upland interior is not suitable as farmland but there is still plenty of room for agricultural expansion. Only 7% of the area between sea level and an elevation of 200 m is currently under cultivation but it is estimated that it would be possible to increase this to 63% – an eight-fold extensification. Icelandic lowlands currently comprise a fine-scale mosaic of open semi-natural habitats and cultivated fields (primarily for silage production to feed animals), making most of the landscape much more heterogeneous than in countries with a longer history of commercial farming.

blog hay and semi-naturalTwo previous WaderTales blogs have already shown that:

Given that farm production is predicted to increase, that farmers like breeding waders and that some intensively-managed fields can be attractive to waders, is it possible to design farmed landscapes that will work for birds and farmers?

Increasing inputs and reducing heterogeneity

blog nice wetlandGlobally, the expansion and intensification of agriculture has altered landscapes and the associated homogenisation has greatly influenced bird abundance and reduced biodiversity. Populations of numerous species, particularly specialist species, have declined, as agriculture has expanded, while generalist species have often thrived in agricultural habitats.

There is no shortage of examples in which highly intensively managed farmland is shown to be bad for breeding waders. In the monoculture hay-meadows of the Netherlands, Black-tailed Godwit productivity is really low, for instance. These fields have been drained, fertilised and re-sown, in order to create easily-managed carpets of single-species grass that can be cut several times a year. There is more about this in this paper by Roos Kentie.

blog hay fieldAlthough there are some areas of Iceland in which farming is quite intensive, there are many others where farmers have a lighter touch. For instance, nutrient-poor dwarf birch marshes may occasionally be grazed by sheep in the summer but these areas have never received applications of artificial fertiliser. At this end of the intensification continuum, increasing agricultural operations may have benefits for breeding waders. When a patch of rough grazing is ploughed and turned into a hay meadow, the addition of fertilisers can potentially increase soil fertility and create an attractive place for waders to feed. A hay meadow within a local area that is dominated by dwarf birch marsh could effectively increase the heterogeneity (& nutrient-richness via spill-over) of the local area, albeit in an artificial way. In the UK, Golden Plovers breeding on moorland are known to travel up to 7 km to feed on fertilised hayfields with high earthworm densities. This paper by James Pearce-Higgins & Derek Yalden in IBIS provides a nice example of how low intensity agriculture can provide resources for waders in the wider landscape.

Researching waders and landscapes

blog dbmLilja’s work in the Southern Lowlands of Iceland focused upon understanding how agriculture influences breeding wader densities and how these relationships might influence future change. At its heart were counts of adult waders encountered along 200 transects (totalling over 100 kilometres) within semi-natural habitats, visited at several stages during the breeding seasons of 2011 and 2012.

As well as counting birds, Lilja categorised habitats within 500, 1000, 1500 and 2500 metres of the transects, which she called buffer area in the paper. Interestingly, and usefully for later analyses, the distribution of different habitat types is pretty uniform across these scales, in this part of Iceland, with little substantial difference according to elevation. In the diagram below, the 200 transects (a) have been split between those below 50 m above sea level (b) and those higher than 50 m (c).

buffers

Landscape-scale effects

To fulfill the various demands of parents and their offspring, waders need diverse resources on or near their territory. An adult can feed a kilometre or more away from its nest, between incubation bouts, and chicks are mobile from an early age. Tagging has shown that young Black-tailed Godwits can move up to 3 km in the first five days of life, just to give one example. In this open landscape, breeding success is likely to be a function of habitat availability at a broad scale. This is explored in a WaderTales blog about nesting Whimbrel.

blog redshankUsing data collected from these 200 lowland transects, Lilja was able to establish relationships between breeding wader densities and the amount of cultivated land and wetland in the surrounding landscape. These two habitat types were considered because future agricultural expansion is likely to take place on drained wetlands that have high conservation value. In her analyses she assessed the extent to which the amount of cultivated land in the surrounding landscape affects wader densities on semi-natural land, and then considered the potential effects of future agricultural expansion on wader populations. There was substantial variation in the density of all of the six most common wader species recorded on the transects, ranging from 0 to 284 birds/km2.

Lilja found that wader densities in semi-natural habitats were consistently greater when the surrounding landscapes had more wetland, at scales ranging from 500 m to 2500 m, indicating the importance of wetland availability in the local neighbourhood. However, the effects of cultivated land in the surrounding landscape varied with fertility and landscape structure, which was largely defined by altitude.

  • In fertile, low-lying coastal areas (from sea-level to 100 m altitude), wader numbers declined with increasing amounts of cultivated land (and the lowest densities occurred in areas dominated by cultivation). This suggests that further conversion of semi-natural habitats into farmland is likely to severely impact waders in low-lying areas.
  • In less fertile habitats at higher altitudes (between 100 m and 200 m), the lowest densities occurred in areas without cultivated land. This suggests that additional resources provided by cultivated land may have a more positive affect in the less-fertile, higher altitude areas.

blog blackwitThe relationships between the areas of wetland and agriculture in the surrounding landscape and the density of waders vary between species, as you can read in some detail in the paper. A few highlights are:

  • With increasing area of cultivated land, densities of Golden Plover, Dunlin and Whimbrel declined significantly at lower altitudes but increased at higher altitudes. These are the three species that would appear to respond most positively to the addition of pockets of cultivated land within a semi-natural matrix of less fertile land, that tends to be found at higher elevations.
  • Higher amounts of wetland were associated with increased densities of Dunlin and Black-tailed Godwit, but lower densities of Redshank. Golden Plover numbers were unaffected by amount of wetland in the surrounding landscape.
  • Whimbrel densities increased with wetland area, at higher altitudes. Wet patches have been shown to be very important to Whimbrel chicks, as you can read in this WaderTales blog about research in Shetland.
  • At lower altitudes, Snipe densities increased with the amount of wetland area in the local vicinity. This relationship was less pronounced at higher altitudes, which tend to be less effectively drained and hence generally wetter.

dunlin graphic

What now?

Changes in Icelandic landscapes are to be expected in the coming years, as most farmers intend to increase their areas of cultivated land. This expansion will inevitably have impacts upon the internationally important breeding wader populations of Iceland but the level of such impact will depend on where the expansion will occur. This paper shows that increases in the area of cultivated land at lower altitudes in Southern Iceland are more likely to result in declines in wader density than in less fertile areas, when tend to occur at slightly higher altitudes (still under 200 m above sea level). An important next step will be to identify the landscape structures and scales of management that can continue to support high densities of breeding waders.

blog coastal wetlandGiven the international importance of Iceland as a home for breeding waders it would be nice to think that this paper can be used to develop national land management policies that can prevent the unintended loss of species such as Golden Plover and Snipe, which landowners value and wish to preserve. At the farm and community level, the paper highlights the key importance of maintaining the complex and heterogeneous landscapes of lowland Iceland, retaining as many as possible of the remaining wetland patches and pockets of semi-natural land within even the most intensive of farming areas.

The paper may well be of interest to conservationists who are struggling to reverse wader declines in other parts of the world. In Southern Iceland, where 7% of the land is being farmed relatively intensively within a fine scale mosaic of both wet and dry semi-natural habitats, it is possible to support hundreds of waders per square km across the wider countryside. Can this situation be replicated across large tracts of land in other countries?

Take home message and paper

blog heterogeneousThis paper provides a useful reminder that the links between land use changes and biodiversity implications can be highly context-dependent. Further agricultural conversion of wetlands and rough grazing areas in the fertile low-lying areas of Iceland is likely to be detrimental for breeding waders, but such effects may be less apparent in less fertile, higher altitude areas. Here, the conversion of some land from rough-grazing to hay meadows may provide feeding opportunities off-territory for Dunlin, Golden Plover and Whimbrel. The scale at which the addition of cultivated areas is beneficial to breeding waders has yet to be determined.

This paper is published as:

Interacting effects of agriculture and landscape on breeding wader populations. Lilja Jóhannesdóttir, Jennifer A. Gill, José A. Alves, Sigmundur H. Brink, Ólafur Arnalds, Verónica Méndez and Tómas Grétar Gunnarsson https://doi.org/10.1016/j.agee.2018.11.024

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GFA in Iceland

Graham (@grahamfappleton) has studied waders for over 40 years and is currently involved in wader research in the UK and in Iceland.  He was Director of Communications at The British Trust for Ornithology until 2013 and is now a freelance writer and broadcaster.