UK waders: “Into the Red”

If you ask British birdwatchers to name the eleven wader species that are causing the most conservation concern in the UK, they would probably not include Dunlin. Curlew may well be top of their lists, even though the most recent population estimate is 58,500 breeding pairs, but would people remember to include Ruff?

This blog is a new incarnation of Nine Red-listed UK Waders, explaining why there are now eleven shorebird species on the UK Red List. Its publication coincides with the appearance of the BTO book Into the Red which highlights the problems being faced by seventy species that breed and/or spend the winter in the United Kingdom. The work of seventy writers and seventy artists has been curated by Kit Jewitt (@YOLOBirder on Twitter) and Mike Toms (BTO), and the book is being sold to support the work of both the BTO and the Rare Breeding Birds Panel.

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 Turtle Dove and Willow Tit, but why are 5.3 million pairs of House Sparrow (right) in the same company?

The list is very important because it helps to set the agenda for conservation action, influences 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 Turtle Dove – and the speed of decline of common species. Data collected by volunteers, working under the auspices of the British Trust for Ornithology (BTO), measured a population decline for House Sparrow of 69% between 1977 and 2018, which is worrying enough to earn this third most numerous breeding species in the UK a place in Into the Red.

Mark Eaton of the Rare Breeding Birds Panel explains how listing works.

The Birds of Conservation Concern (BOCC) system, through which the Red List and Amber Lists 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, the 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.

This blog is about the eleven waders in Into the Red, but there are 59 other fascinating species accounts and wonderful artworks. Each of the species accounts below starts with a quote from the book and is accompanied by a low-resolution version of the artwork.

Dotterel

“Dot, dot, dot, Dotterel. Disappearing – a dash, dashing off the page.” – Alicia Hayden

The UK’s small population of Dotterel is restricted to the high tops of Scottish mountains, with only occasional breeding reports elsewhere. Three decades ago, the warning bells were raised, as warming conditions and an elevated snowline turned the Dotterel into a poster bird for climate change campaigners. The detailed reasons for the species’ 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. See also Scotland’s Dotterel: still hanging on, which highlights the pressures that youngsters face in North Africa, during the first eighteen months of their lives.

Ringed Plover

“The gentle scuttle over the rocks, the unmistakable bum-bob and the elegant glide into a nest site” – Dan Rouse

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 constitute a large percentage of the Ringed Plovers that breed in many of these countries.

The Wetland Bird Survey graph 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 on the open coast did not drop as much (see Waders on the coast) and those on estuaries may have stabilised or even have increased slightly, since 2014, but Ringed Plovers need some good breeding years. Disturbance is an issue for nesting Ringed Plovers, which share their beaches with visitors and dogs, as discussed in this blog about the ‘no go’ areas along the Norfolk and Suffolk coasts – On the beach. Winter disturbance can be a problem for waders too (see Disturbed Turnstones).

Lapwing

“I heard them before I saw them. Like the plaintive squeak of a rubber toy, or an oboist tuning up …” – Tessa Boase

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 55% between 1967 and 2018, according to BirdTrends 2020, 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. There are many predators that line up to take Lapwing eggs so it pays to nest in loose ‘colonies’, so that guard duties can be shared.

Whimbrel

“Whimbrel have been doing this journey, between tundra and heath of northern Europe to mudflats and mangroves of Africa, for at least 1.9 million years” – Rosie Ellis

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 UK population nesting almost exclusively on Shetland. The latest estimate is 290 pairs (2009), down from an estimate of 530 pairs, published in 1997. We await the results of a 2021 survey with interest. Many pairs have been lost from Unst and Fetlar and this blog about habitat requirements 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?). Hints of future issues for Eurasian Whimbrel are coming from Iceland, where forestry is squeezing them out of some key areas: Iceland’s waders need a strategic forestry plan.

Curlew

“A song that seems to split in mid-air and take the heart in two directions at once” – David Gray

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 disappeared in just 30 years. These blogs provide more information about the decline and review some of the reasons.

• Is the Curlew really near-threatened?
• Curlews can’s wait for a treatment plan
• Ireland’s Curlew Crisis
• More Curlew chicks needed

Across every part of the UK, stakeholder groups have come together to support populations of breeding Curlew, using a mixture of habitat management, predator reduction and nest protection measures. One recent innovation is to raise chicks in captivity, in an attempt to boost local populations in England. There’s more in Will head-starting work for Curlew?

Black-tailed Godwit

“These birds become old friends and open our eyes to the world of migration” – Jennifer Gill

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, as you can discover in England’s Black-tailed Godwits. A head-starting project in the Washes is boosting the number of chicks; so much so that released birds now make up more than 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

“But then, good grief, in May and June, I’m treated to a different plume; A glorious crown, I gush and swoon – and then, no doubt, I change my tune.” – Jess French

Some Ruff spend the winter months in the UK and numbers are boosted in spring as birds pass through on their way from Africa to Scandinavia and the Baltic countries. Occasionally, males in glorious breeding attire will display in leks, perhaps attracting the attention of females. As a (very) scarce breeder, Ruff automatically earns a place on the Red List.

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. Lekking males cause 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).

Dunlin

“Memories of sunny days, swirling flocks of waders and blisters from closing metal rings still linger. How can a bird that was so numerous less than 50 years ago now be Red-listed?” – Graham Appleton

There are good reasons for the addition of Dunlin to the UK Red List; breeding numbers of the schinzii race have declined significantly and the number of wintering alpina Dunlin in Great Britain dropped 10,000 between two periods that were only eight years apart, as you can read in this blog about population estimates for waders.

The fall in breeding numbers is probably the bigger problem, as indicated by range reductions in successive breeding atlas periods (1968-72, 1988-91 and 2008-11). It’s hard to monitor what is happening to numbers on a year-by-year basis because the breeding distribution is too patchy and thin to be picked up via the Breeding Bird Survey. Alarm bells are being raised in Ireland, where numbers have dropped to between 20 and 50 pairs (Status of Rare Breeding Birds across the island of Ireland, 2013-2018), and in the Baltic, where numbers have fallen by 80% since the 1980s. There’s a WaderTales blog about Finnish Dunlin.

The winter decline in the UK may or not be an issue, although it has to be considered as part of large-scale moderate losses across the whole of western Europe. There is a theory that, over the years, as winter conditions on the continental side of the North Sea have become less harsh, new generations of juvenile alpina have settled in countries such as the Netherlands, instead of continuing their southwesterly migrations from northern Russia. Once a wintering site has been chosen, individuals are site faithful, so one ends up with newer generations on the continent and ageing adults in the UK and Ireland. WeBS counts for Dunlin are half what they were 25 years ago.

Purple Sandpiper

“It’s an easy species to overlook, the Purple Sandpiper. For a start, they’re not purple” – Mark Eaton

Purple Sandpiper earns its red listing because a very small number of pairs nest in Scotland. Proof of successful breeding is rare and the species may drop off the list at the next review, as Temminck’s Stint did in 2015. Extirpated species (birds that no longer breed) are not red-listed.

In winter, the rocky coasts of the UK are home to Purple Sandpipers from the Arctic, with a suggestion that North Sea coasts, south of Aberdeen, mainly play host to birds from Spitsbergen and northern Scandinavia, with Greenlandic and Canadian birds more likely to be found further north and on the Atlantic coast. Coastal numbers declined by 19% between 1997/98 and 2015/16, according to the Non-estuarine Waterbird Survey, and WeBS counts suggest numbers have at least halved over a period of 25 years. The Highland Ringing Group has shown that the number of young Purple Sandpipers has been declining on the Moray Firth, suggesting several years with relatively poor breeding success, for birds migrating from the northwest, or short-stopping by new generations of youngsters, as discussed for Dunlin. Perhaps they are wintering in Iceland these days?

Woodcock

“Like clockwork, I’d encounter this sight at 7 pm each summer evening as one flew over my head in the back garden, heading towards the thick woodland.” – Megan McCubbin

The presence of Woodcock on the Red List causes heated debate; how can this still be a game species? Red-listing is indisputable; the most recent 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 GWCT emphasise the importance of reducing pressures on British birds.

Red-necked Phalarope

“The evening light was beautiful, and it was just amazing to watch it spinning around in characteristic fashion” – Dawn Balmer

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 108 pairs in 2018 reflects conservation success (The Rare Breeding Birds Panel). 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.

In conclusion

The Red List creates some strange bedfellows. In the book, Turtle Dove follows Herring Gull (right); 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.

Into the Red aims to raise awareness of the UK’s most at-risk bird species, eleven of which are waders, and to raise money to support the Rare Breeding Birds Panel and BTO research scientists. This is a follow-up to Red67, published in 2019 and based on the Red List from 2015. It is sad that this version covers 70 species, rather than 67. Worryingly, the first Red List, produced in 1990, only had 36 species on it.

Into the Red is a lovely book that captures the thoughts and images of a generation. Details of how you can order a copy from the BTO can be found here.

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

A Whimbrel’s year

There’s a lot to fit into twelve months if you’re a Whimbrel. In the last paper from his PhD, Camilo Carneiro assesses whether Icelandic Whimbrel can always manage to complete the annual cycle of migrate-breed-fatten-migrate-moult-fatten in just 365 days.

YY-LL (Yellow yellow – lime lime) collected data for several years.

What happens if a pair of Whimbrel loses a first clutch and a successful, late breeding attempt delays departure from Iceland, for instance? Is there the flexibility to make up for lost time during a west-African winter? Some answers are provided in a paper by Camilo Carneiro et al in The American Naturalist.

Facing the consequences

We know that large waders sometimes take a year off from breeding, as discussed in Teenage waders, suggesting that they may not always have the resources they need to breed every year. This blog, based on a paper by the Bird Ecology Lab team in Chile, tells the tale of a few Hudsonian Godwits that headed for the pampa grasslands of Argentina in spring, instead of migrating to Alaska.

As discussed in Gap years for sandpipers, taking a year off may make no difference to expected lifetime breeding output and could be more common when individuals spend the non-breeding season a long way from nesting areas or in poor quality sites. If Iceland’s Whimbrel are able to compensate for any delays they face during the course of the annual cycle then perhaps that suggests that all is well for this population that migrates all the way to West Africa at the end of the summer breeding season?

The story so far

Whimbrel only spend three months of the year in Iceland, with the rest of the time spent some 6000 km further south. In July or August, an adult will exchange the sparsely vegetated river plains and night-time frosts of Iceland for mud, mangroves and tropical temperatures. The diet changes too, from terrestrial invertebrates and crowberry to crabs.

Camilo Carneiro started a PhD on Iceland’s breeding Whimbrel in 2015, continuing the work of his supervisors, Tómas Gunnarsson of the University of Iceland and José Alves from the University of Aveiro (Portugal). Using geolocator tags he investigated the capacity for Whimbrels to undertake non-stop journeys, demonstrating that autumn migration was generally direct but spring migration for most birds included a stop, often in Ireland or the UK. You can read more in Iceland to Africa, non-stop. Birds that need to (or choose to) take a break delay their arrival in Iceland by about ten days.

Subsequent papers by the same team have shown that the most consistent point of the annual migration story is departure from Africa and shown links between weather and phenology. These two papers have been covered in the WaderTales blogs Whimbrel: time to leave and A Rhapsody of Whimbrel. In an attempt to discover the best places to spend the winter months, Camilo analysed tag and colour-ring data to work out links between conditions experienced in wintering locations and subsequent breeding success, as discussed in the blog Winter conditions for Whimbrel.

Seven years of data

To investigate how migratory animals navigate their annual schedule, and where and when they can make adjustments to their timings, Camilo Carneiro and his colleagues used annual-cycle data of 38 Icelandic whimbrels tracked over 7 years. They asked three questions:

• Does the change in the timing of one event in the annual calendar, such as a late breeding season, affect the timing of subsequent events, perhaps with further down-stream domino effects?
• Can individuals compensate for delays, on migration for instance, by spending less time on the next stage of the annual cycle, e.g. by reducing a stop-over?
• Are there potential fitness consequences? Do birds that are subject to delays breed later? In waders, earlier chicks are more likely to recruit to the breeding population so being just a few days late returning to Iceland may have consequences.

During the period 2012 to 2018, a total of 78 geolocators were deployed on Whimbrel breeding in Southern Iceland. The device was attached to a leg-flag in one year (see picture) and usually collected in the subsequent breeding season. In most cases, a replacement geolocator was fitted, in order to collect further data on that individual. Unsurprisingly, it became harder to catch tagged birds over time, as birds learned to recognise nest traps and research vehicles. The fact that so much valuable information was collected from the same birds is testament to Camilo’s patience. Sixty-six geolocators were retrieved from 39 individuals. Birds could only be caught when incubating a full clutch of eggs so nest losses due to predation affected the likelihood of recapture.

Please see the paper in The American Naturalist for full details of the methods used to collect data on breeding success and for interpretation of data collected using geolocators.

Whimbrel YY-LL

Before looking at the results in the paper, here’s an example of data collected using geolocators, for two years in the life of YY-LL (Yellow Yellow – Lime Lime), pictured alongside.

In 2015, YY-LL nested successfully and left Iceland on 16^th August. After four days of direct flight, he reached Guinea-Conakry. His nesting attempt in 2017 was unsuccessful and he migrated south a little earlier, on 5^th August, again taking four days to fly 6000 km.

In the springs of both 2016 and 2018, YY-LL left the winter grounds on 22^nd April, arriving in Ireland on 26^th April in 2016 and on 25^th April in 2018. Migration from Ireland to Iceland took place between 5^th and 7^th May in 2016 and between 7^th May and 9^th May in 2018.

YY-LL hints at strong consistency of spring migration timing, independent of nest success.

Results

The 38 tagged Whimbrel provided information about 76 autumn migrations and 60 spring migrations. Most of the birds (89%) spent the winter between Senegal and Sierra Leone, particularly in Guinea-Bissau and Guinea, with one bird in Portugal and the rest in coastal northwest Africa.

As is usual in waders, females left Iceland before males, the difference being typically around six days. Although failed breeders did depart earlier than birds that successfully reared chicks, the difference was not great, again averaging around six days.

There was no suggestion that birds that left Iceland late in the season ended up on a delayed schedule for return to Iceland in the subsequent spring. This implies that resources in Africa were sufficient to ‘catch up’ with earlier birds, despite the need to complete a full moult and to prepare for another 6000 km migration.

As indicated in previous papers (and in the blogs mentioned above) spring departure dates of tagged birds from Africa were not different for different countries or for different sexes. However, birds that stopped in Europe tended to leave Africa earlier (19^th April on average) than those that made direct spring flights (30^th April). These latter birds tended to arrive in Iceland about a week earlier than birds on a two-stage migration, representing a neat, overtake manoeuvre! Typically, males arrived in Iceland about a week earlier than females.

For the sample of tagged birds, neither the autumn departure date from Iceland nor wintering location had any apparent effect on the arrival date in the next spring.

There seems to be a strong signal that, just as YY-LL did, an individual Whimbrel can make up for any delays incurred, with birds that arrive at a location later spending less time there, whether that be a wintering site or a spring stopover location. Females tended to spend longer at spring stopover locations, which ties in with the earlier arrival of males in Iceland. The graph alongside illustrates these two points. Birds that left Africa earliest spent more than 15 days at stopover sites but birds on a later schedule stopped off for as few as 6 days. Triangles represent males and squares are females.

Over the course of a year

Putting this all together, Camilo and his colleagues found that individuals appear to use the wintering sites to compensate for delays, these mostly having been associated with a successful previous breeding season. The wintering season is up to 38 weeks long so a Whimbrel that heads south a little late has plenty of time in which to catch up with earlier birds. The timings for other wader populations that spend shorter periods in wintering locations may be more constrained, given that post-breeding moult might take 20 weeks and the time to fatten up for migration can add an extra seven weeks.

Once a bird leaves Africa, it is harder to compensate for delays, although attempts are made to do so, with later individuals stopping for shorter times at spring stop-over sites and then nesting shortly after arrival in Iceland. Data in the paper suggest that it is not possible to catch up completely, before the start of the breeding season, if time is lost on the way north. Given the known link between lay-date and nesting success, these spring delays may have consequences for productivity and reduce the capacity to re-nest following clutch loss.

Iceland’s Whimbrel

Camilo’s research suggests that adult Whimbrel in the south of Iceland have the capacity to make up for any delays that they face during the annual cycle. The same may not be true for other large waders, the populations of which are mostly in decline. The blog Why are we losing out large waders? reminds us that two curlew species are thought to be extinct or on the verge of extinction and that most of the rest are in trouble.

There are increasing pressures on Whimbrel breeding in Southern Iceland, associated with new forestry plantations and infrastructures such as road developments and power lines

All is not necessarily well for Iceland’s waders either. Two 2022 papers by Aldís Erna Pálsdottir, looking at the effects of forestry and power-lines, suggest that the Whimbrel is one of the wader species most seriously impacted by ongoing changes to the Icelandic landscape, as discussed in Power-lines and breeding waders and Iceland’s waders need a strategic forestry plan. These pressures seem to be reflected in poorer breeding output, as suggested by counts of family parties of Whimbrel made by Tómas Gunnarsson and colleagues in annual June and July surveys.

Camilo’s paper may indicate that adult Whimbrel can cope with all that life throws at them but if they cannot raise enough chicks the species will still be in trouble. With financial support from the Icelandic Centre for Research, Camilo is now studying the challenges that chicks face, as they prepare for their first migration from Iceland to Africa.

Here’s the link to the paper:

Annual schedule adjustment by a long-distance migratory bird. Camilo Carneiro, Tómas G. Gunnarsson & José A. Alves. The American Naturalist. doi.org/10.1086/722566

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

January to June 2022

Here are brief summaries of the first nine WaderTales blogs of 2022. As ever, I am grateful to the authors of the papers that underpin the blogs; they have worked with me to make sure that I get the stories right! I have not covered every new paper; perhaps your favourite is in the pipeline or perhaps I did not happen to spot it? The blogs are described in order of publication.

Welsh Oystercatchers

To explain how flexible Oystercatchers can be in response to changes in their food supply, Katharine Bowgen has brought together long-term data collected by wader ringers and WeBS counters, and added in annual assessments of cockle stocks on the Burry Inlet (South Wales). This paper has a particular resonance, as I remember teaching students about the Burry Inlet Oystercatcher controversy of the 1970s, when complaints from shellfishers led to the deaths of thousands of birds. We understand more about the relationship between shellfish stocks and bird numbers now but what happens when Oystercatchers can’t find food? This paper makes a strong case for the protection of networks of sites, so that individuals have alternatives when needed.

Australian stock-take

One of the great joys of writing WaderTales blogs is that I get to ‘visit’ the flyways of the world without having to burn carbon. How many shorebirds use the East Asian-Australasian Flyway? is a flyway-wide stock-take of the waders that visit Australia and New Zealand, led by Birgita Hansen. It is shocking that a flock of 350 Far-eastern Curlew now constitutes 1% of the global population and that the population of Curlew Sandpipers has halved in double-quick time, but the key strength of the paper is the clear explanation of a methodology that can be used in the future, to monitor changes in numbers.

Chick vocalisation

Big analyses of data sets are very important but it’s lovely when you learn more about the natural history of species that birdwatchers know well. In Australia, Kristal Kostoglou recorded the calls of the chicks of Red-capped Plovers and Southern Masked Lapwings, that were being ringed and measured in the hand. In Chick squeaks I describe how calls get deeper with age, which is not surprising, but that the calls of males and females can become distinguishable from a very early age. Male Red-capped Plover chicks are more demanding than their sisters!

Trans-oceanic migration

There have been several recent wader papers that interpret data obtained from birds when on migration. One of the interesting questions being asked is, “Do shorebirds account for wind displacement continuously or correct for drift later?”. Navigating a vast ocean summarises Jenny Linscott’s work on Hudsonian Godwits, as they cross the Pacific Ocean and then the Gulf of Mexico, on their way from Chile to Alaska. She and her fellow authors show that flocks make continuous adjustments, demonstrating that birds ‘know where they are’ and giving them the ability to fly extremely long distances without running out of energy. There’s some clever maths too!

Hiding in the trees

In the second paper from her PhD, Triin Kaasiku looks at the breeding success of Estonian coastal waders that nest at different distances from woodland. Keep away from the trees describes these ‘edge effects’. In a part of the world where waders are in diminishingly short supply, hatching success is six time as high in open areas as in areas that are within one kilometre of forest edge. The Baltic coast used to be a haven for species such as Curlew and Dunlin but reduced grazing and forestry plantations have provided hiding places for predators. Alongside increased predation, breeding waders are also having to contend with an increasing numbers of nest inundations, arising from summer storms.

Curlew hunting

Curlew hunting stopped in Great Britain in 1982, when the declining wintering population received protection under the new Wildlife & Countryside Act. A fascinating paper by Ian Woodward and BTO colleagues teases apart the positive effects of the cessation of shooting and more benign winter weather. It is summarised as Curlew: after the hunting stopped.

I am old enough to remember when Curlew were hunted in East Anglia. The pâté made from autumn-shot birds is reputed to have been very tasty; I recall Clive Minton getting back in his land-rover and reporting that he had been offered some, when asking for permission to cannon-net Curlew on a Norfolk land-owner’s estate.

Personal appreciation of Whimbrel

On 27 April, Jenny Gill and I were at Eyrarbakki, on the south coast of Iceland. As we watched, small groups of Whimbrel were coming in off the sea. Others were resting on the seaweed-covered rocks, a few were feeding and some flew straight by. Watching waders arrive in Iceland is always magical but, from sightings of satellite-tagged Whimbrel, we could be pretty sure that these tired birds had just completed five-day, direct flights from west Africa. I could not wait to get back to base and to share our observations. It was a good excuse to round up the Whimbrel stories in other WaderTales blogs, as you can read in Whimbrels arrive in Iceland.

Power-line problems

We have seen huge changes in Iceland, since we first visited in 2000, but how are these affecting shorebirds? In the first paper of her PhD (Effects of land conversion in sub-arctic landscapes on densities of ground-nesting birds), Aldís Pálsdóttir investigated how distributions of breeding waders are affected by power-lines. She discovered significantly depressed numbers several hundred metres from the transmission lines, with Whimbrel and Redshank being the most obviously impacted. Her results are written up as Power-lines and breeding waders. With an increasing global reliance on electricity, these are important findings for planners and conservationists.

Conflict with forestry

Just a few days later, Aldís Pálsdóttir’s second paper was published. By mapping distributions of breeding waders in the vicinity of forests, she has shown that new plantations have a massive effect on distributions. In lowland Iceland, the most vulnerable species appear to be Dunlin and Oystercatcher, followed by Whimbrel, Black-tailed Godwit and Golden Plover. It should be noted that three-questers of Europe’s Whimbrel nest in Iceland, as well as half of the Golden Plover and Dunlin. Aldís and her fellow authors argue that Iceland’s waders need a strategic forestry plan. They estimate that recently-planted woodland and forests have already removed the breeding territories of tens of thousands of waders.

Blogs from previous years

WaderTales blogs in 2021

WaderTales blogs in 2020

WaderTales blogs in 2019

WaderTales blogs in 2018

WaderTales blogs in 2017

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

Iceland’s waders need a strategic forestry plan

More and more trees are being planted in lowland Iceland – and further increases are planned, in part encouraged by the suggestion that this will mitigate for climate change. Forestry is potentially bad news for Whimbrel, Black-tailed Godwit and other waders that breed in open habitats, and which migrate south to Europe and Africa each autumn. Are there ways to accommodate trees while reducing the damage to internationally important populations of waders?

Pressure on Iceland’s breeding waders

Iceland is changing; more people want second homes in the countryside, the road network is being developed to cope with more and more tourists, new infrastructure is needed to distribute electricity, agriculture is becoming more intensive and there is a push to plant lots more trees. The south of the country is seeing the most rapid loss of open spaces, providing opportunities to study how these incursions affect ground-nesting species, particularly breeding waders.

One of the big changes, especially in Southern Iceland, has been the planting of non-native trees, as shelter belts around fields and country cottages and, more significantly, as commercial crops. Iceland has been largely treeless for hundreds of years but climatic amelioration has facilitated rapid forestry development in areas where tree growth was previously limited by harsher environmental conditions. Seeds of some non-native species are blown on the wind for a kilometre or more, to germinate in open land, well beyond the edge of planned forests.

Most of the new forests are in lowland areas, where we also find the most important habitats for many ground-nesting bird populations. Lodgepole pines may be good news for Goldcrest and Crossbills but not for species such as Golden Plover, Dunlin & Redshank. For breeding waders, the most obvious impact of a new forest is direct loss of breeding habitat but trees can have wider effects, by providing cover for predators and breaking up swathes of open land that are used at different stages of the breeding season. Little is currently known about how predators in Iceland use forest plantations but any perceived risks of predator presence and reduced visibility is likely to influence densities of birds in the surrounding area.

Iceland’s open habitats have suited breeding waders for hundreds of years

Aldís E. Pálsdóttir’s studied changing bird populations in lowland Iceland during her PhD at the University of Iceland, in collaboration with researchers from the University of East Anglia (UK) and the University of Aveiro (Portugal). Among the most concerning of these changes is the rapid expansion of forestry in these open landscapes.

Assessing the potential impacts of trees

In a 2022 paper in the Journal of Applied Ecology, Aldís assesses whether densities of ground-nesting birds are lower in the landscape surrounding plantations and whether these effects vary among plantations with differing characteristics. She and her fellow authors then quantified the potential impact of differing future afforestation scenarios on waders nesting in lowland Iceland.

Forestry currently covers about 2% of Iceland’s land area so the potential for growth is massive. In 2018, the Icelandic government provided additional funding to the Icelandic forest service to increase the number of trees planted, with a goal of enhancing carbon sequestration. As forestry primarily operates through government grants to private landowners, who plant trees within their own land holdings, plantations typically occur as numerous relatively small patches in otherwise open landscapes. These features make Iceland an ideal location in which to quantify the way that plantations affect densities of birds in the surrounding habitats, and to identify afforestation strategies that might reduce impacts on globally important wader populations.

To measure the effects of plantation forests on the abundance and distribution of ground-nesting birds, in particular waders, 161 transect surveys were conducted between May and June 2017. To avoid systematic bias arising from possible “push effects” of corralling birds in front of the surveyor, surveys were conducted along transects that started either at the edge of the plantation, with the observer moving away (79 transects), or started away from the plantation, with the observer walking towards it (82 transects). Please see the paper for the full methodology. The variation in density with distance from plantation was used to estimate the likely changes in bird numbers, resulting from future afforestation plans, and to explore the potential effects of different planting scenarios.

Bird communities change around plantations

Snipe densities are highest close to young forests

On the transects, 3713 individual birds of 30 species were recorded. The nine most common species (excluding gulls, which rarely breed in the focal habitats) were seven waders (Oystercatcher, Golden Plover, Dunlin, Common Snipe, Whimbrel, Black-tailed Godwit & Redshank) and two passerines (Meadow Pipit & Redwing). These species accounted for 88% of all birds recorded.

• Of the seven waders, Snipe was the only one found in significantly higher numbers closer to plantations. Snipe density declined by approximately 50% between the first (0-50 m) and second (50-100 m) distance intervals, suggesting a highly localised positive effect of plantations on Snipe densities.
• Densities of Golden Plover, Whimbrel, Oystercatcher, Dunlin and Black-tailed Godwit all increased significantly with increasing distance from plantations. Dunlin and Oystercatcher showed the largest effect (~15% increase per 50 m), followed by Whimbrel (~12%), Black-tailed Godwit (~7%) and Golden plover (~4%).
• Although Redshank did not show a linear relationship with distance from plantation edges, densities were lowest close to the plantation edge.
• There were more Redwings close to woodland edges but Meadow Pipit showed no change in density with distance from plantations.

Golden Plover, Whimbrel and Snipe were found in lower densities close to the tallest plantations (over 10 m), when compared to younger plantations (tree height 2m to 5m), suggesting that the impact of forests gets more pronounced as the trees grow. Plantation density and diameter had no additional effect on the species that were in lower densities closer to the plantations, implying that the mere presence of plantations induces the observed changes in abundance. See the paper for more details.

The bigger picture

Aldís Pálsdóttir and Harry Ewing walked every step of every transect and made detailed counts of what they saw – data that are invaluable when considering local impacts of plantations – but the paper becomes even more interesting when the authors look at the bigger picture. When plantations are distributed across these open landscapes, in different configurations, what will be the accumulated effects on the numbers of breeding waders? They estimate likely changes in abundance resulting from planting 1000 ha of plantation in different planting scenarios, ranging from a single block to lots of small patches.

• Planting 50 smaller patches of 20 ha, instead of 1000 ha of forest in one large patch, is estimated to double the resulting decline in abundance (because there is more forest edge and hence a bigger effect on more open habitat)
• This effect increases even further as the patches become smaller; in their models, planting 1000 blocks each of 1 ha would have nine times the impact of planting one forest of 1000 ha.
• Proximity of woodland seems to be the driver of local distributions of breeding waders so the authors suggest that the amount of edge (relative to area) should be minimised, to reduce the impact of a plantation – which means making forests as near circular as possible.

It is clear that fewer larger forestry plots are likely to be less bad than lots of small, local plantations, in terms of the effects on wader populations. The figure below illustrates how much more land is affected when one woodland is replaced by four with the same total area. The grey area (equivalent to a 200 metre annulus) accounts for 88 hectares in the one-patch illustration and 113 hectares for four patches.

An urgent need for action (and inaction!)

Iceland holds large proportions of the global nesting populations of Golden Plover (52%), Whimbrel (40%), Redshank (19%), Dunlin (16%) and Black-tailed godwit (10%) (see Gunnarsson et al 2006) and is home to half or more of Europe’s Dunlin, Golden Plover and Whimbrel. Data in the table alongside have been extracted from Annex 4 of the report, which was discussed at the 12^th Standing Committee of AEWA (Agreement on the Conservation of African-Eurasian Migratory Waterbirds) in Jan/Feb 2017.

Aldís measured the areas of 76 plantations in her study, using aerial photographs. The total area of woodland was about 2,800 ha and the total amount of semi-natural habitat in the surrounding 200 m was about 3,600 ha. Using the reduced densities that she found on the transects and the direct losses for the plantations themselves, she estimates potential losses of about 3000 breeding waders, just around these 76 forest plots. Extrapolating this figure to the whole of the Southern Lowlands of Iceland, the total losses resulting from all current plantations are likely to already be in the tens of thousands. Worryingly, the densities measured on the transects in this paper (even 700 m from forest edge) were well below those measured (slightly differently) in previous studies of completely open habitat, suggesting that losses may already be significantly higher than estimated in the paper.

A scary statistic in the paper is that “6.3% of the Icelandic lowlands is currently less than 200 m from forest plantations”. Given the incentives to plant lots more trees, this is particularly worrying for species such as Black-tailed Godwits, the vast majority of which breed in these lowland areas (between sea level and 300 metres).

Non-native trees are spreading beyond the boundary of a planned forest

It has been suggested that breeding waders might move elsewhere when impacted by forestry but migratory wader species are typically highly faithful to breeding sites. If birds are not going to move to accommodate trees, then perhaps plantations should be located where bird numbers are naturally low, such as in sparsely or non-vegetated areas, at higher altitudes and on slopes? Planning decisions could usefully be informed by surveys of breeding birds, to identify high-density areas that should be avoided.

The severe impact that planting forests in open landscapes can have on populations of ground-nesting birds emphasises the need for strategic planning of tree-planting schemes. Given Iceland’s statutory commitments to species protection, as a signatory to AEWA and the Bern Convention on the Conservation of European Wildlife and Natural Habitats, and the huge contribution of Iceland to global migratory bird flyways, these are challenges that must be addressed quickly, before we see population-level impacts throughout the European and West African Flyway.

To learn more

The take-home message from this work is clear. Local planning decisions and the ways in which forestry grants are allocated are producing a patchy distribution of plantations across the lowlands of Iceland, and this is bad news for breeding waders.

The paper at the heart of this blog is:

Subarctic afforestation: effects of forest plantations on ground-nesting birds in lowland Iceland. Aldís E. Pálsdóttir ,Jennifer A. Gill, José A. Alves, Snæbjörn Pálsson, Verónica Méndez, Harry Ewing & Tómas G. Gunnarsson. Journal of Applied Ecology.

Other WaderTales blogs that may be of interest:

Forest edges

• The edge effect of forests is discussed in work from Estonia by Triin Kaasiku (see Keep away from the trees). Here she looks at the outcomes of nests at different distances from forest edges.
• Do waders avoid nesting close to trees? This is discussed in Mastering Lapwing Conservation.
• The predator effect lingers long after forests are cleared, according to research described in Trees, predators and breeding waders.

Work by Aldís Pálsdóttir (pictured right)

• The WaderTales blog, Power lines and breeding waders, summarises Effects of overhead power-lines on the density of ground-nesting birds in open sub-arctic habitats.
• Further blogs about wader numbers close to roads and in the vicinity of summer cottages will be added when papers are published.

Changing agricultural systems in Iceland (work by Lilja Jóhannesdóttir)

• Do Iceland’s farmers care about wader conservation? At a time of agricultural expansion, are farmers prepared to leave space for breeding waders?
• Farming for waders in Iceland investigates densities of breeding waders along the gradient of agricultural intensification associated with farming activities.
• Designing wader landscapes investigates whether breeding densities of waders can be maintained, as farming expands and intensification increases.

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

Power-lines and breeding waders

Around the globe, people are consuming more energy, much of which is delivered to cities, towns, individual homes and businesses via over-head electricity cables. In a paper in Ibis, Aldís E Pálsdóttir and colleagues investigate the effects of power-lines on Iceland’s breeding waders. This is the first of several papers from Aldis’ PhD thesis, in which she seeks to understand how forestry and the sprawl of new infrastructures (roads, cottages and power-lines) are changing bird distributions within what were previously open landscapes.

Breeding waders in Iceland

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. In a 2017 report prepared by AEWA (Agreement on the Conservation of African-Eurasian Migratory Waterbirds), in response to concerns about the effects of afforestation on Iceland’s waterbirds, we learn that:

“Iceland is second only to Russia in its importance as a breeding ground for migratory waterbirds in the AEWA region. It supports the most important breeding populations in Europe for six species of waders and is the second most important country for three.”

Data in the table alongside have been extracted from Annex 4 of the report, which was discussed at the 12^th Standing Committee of AEWA in Jan/Feb 2017.

Power lines

For waders nesting in Iceland, power-lines are a new addition to a once-open landscape. Pylons provide potential nesting opportunities for Ravens and perches for Gyrfalcons, while the wires between them are a collision risk. Under power-lines, carcases of swans, geese and waders may attract scavenging Arctic Foxes and Ravens, thereby increasing the activities of nest predators. Perhaps these actual and perceived threats affect densities of breeding waders in the vicinity? Or might birds react to something less obvious, such as the emission of UV light or electromagnetic radiation?

In Iceland, the vast majority of electricity is produced from hydropower or geothermal sources, often long distances from the areas in which the power is used. A new move to develop the wind energy sector has the potential to further add to the number of power lines and introduce them in more areas of the country. Much of the increase in electricity production over the last fifty years has been used to fuel industries such as aluminium smelting and there is the potential to further expand generation capacity, perhaps exporting some electricity to other countries.

Much of Iceland’s electricity is used to power aluminium smelters (here, in Hvalfjörður)

Counting the birds

Aldís counting waders on a transect

Aldís conducted the fieldwork for this study between the 6^th May and the 20^th June 2019, counting birds along 85 transects of between 300 m and 500 m, running perpendicular to power lines. The full methods are described in the paper but it is interesting to see that they included a check to see whether there were different results if walking towards or away from the power lines. Each transect was divided into intervals of 50 m length, each corresponding to 1 hectare of surveyed land. For each power line, Aldís recorded the number of cables, pylon characteristics, and the height and voltage of the line.

Results

In total, 1067 birds of 21 different species were recorded on the 85 transect surveys. Over 90% of sightings were of eight species considered in the subsequent analysis: Dunlin, Black-tailed Godwit, Golden Plover, Meadow Pipit, Redshank, Redwing, Snipe and Whimbrel. Having analysed the data, Aldís and her colleagues concluded that:

• For all eight species combined, the areas closest to the power lines (0-50 m) supported densities of approximately 112 birds/km² (±13 SE) which increased by approximately 58% to 177 birds/km² (±24 SE), in the sector that was between 450-500 m away from the power-lines. On average, there was a 4% increase in abundance between adjacent 50 metre bands.
• At the species level, Redshank (figure below) and Whimbrel density increased significantly with distance from power lines (18% and 9% per 50 m, respectively) but no other significant effects were detected for other species individually.
• There were no detectable difference between types of power-lines or relating to the voltages of the electricity they carried.

Implications of the research

In the paper’s discussion there are questions as to why densities of Redshank and Whimbrel (right), in particular, are lower near power-lines. The two species behave differently while nesting, with Redshanks being nest-hiders and Whimbrel nesting in the open, but previous research has shown that their nest predation rates are quite similar (see Where to nest?).

The reason why significant reductions in density close to power lines were apparent for Whimbrels and Redshanks (but not for other species) is not clear but the authors suggest that sample sizes may have been too low for there to have been measurable effects for species such as Dunlin and Golden Plover (below).

Power lines could have direct impacts, such as increased collision risk, but this may be difficult to establish directly, as the authors suggest that carcasses are likely to be quickly removed by scavengers.

Ravens may find it easier to find and predate nests if there are pylons or wires on which to perch but it will be hard to discriminate between an actual predation effect, reducing numbers in areas close to power-lines, and the avoidance of risky areas because of a perceived threat of predation. This is discussed in Mastering Lapwing conservation.

Given the depressed density of ground-nesting bird species in the vicinity of overhead power lines, the authors of the paper suggest that burying power lines might be a better option, even though there would be temporary disturbance to the ground during installation.

What are the implications for Iceland’s breeding waders?

It would be interesting to calculate how many Whimbrel and Redshank (left) territories would be lost over the course of a 50 km run of power-lines through open landscapes – and then extrapolate that to 500 km and 5,000 km. As shown in the earlier table, 75% of Europe’s Whimbrel breed in Iceland. How vulnerable are they to power-line infrastructures and what might be the impact on a breeding population of over 300,000 pairs?

This is the first of several papers from Aldis’ thesis, in which she seeks to understand the current rapid changes to Iceland’s lowland landscapes. Links to other blogs and papers will be added as they appear. It should soon be possible to reveal the combined effects of these incursions into open wader habitats, by considering plans that might affect these areas over the next twenty years, working out potential losses and setting these numbers in a flyway context.

This paper is published as:

Effects of overhead power-lines on the density of ground-nesting birds in open sub-arctic habitats. ALDÍS ERNA PÁLSDÓTTIR, JENNIFER A. GILL, SNÆBJÖRN PÁLSSON, JOSÉ A. ALVES, VERÓNICA MÉNDEZ, BÖÐVAR ÞÓRISSON & TÓMAS G. GUNNARSSON. Ibis. https://doi.org/10.1111/ibi.13089

Here’s a link to another blog about Aldís Pálsdóttir’s research: Iceland’s waders need a strategic forestry plan.

A complementary set of papers by Lilja Jóhannesdóttir investigated how changes to Iceland’s farming may also be affecting breeding waders. These are discussed in three WaderTales blogs:

• Do Iceland’s farmers care about wader conservation? At a time of agricultural expansion, are farmers prepared to leave space for breeding waders?
• Farming for waders in Iceland investigates densities of breeding waders along the gradient of agricultural intensification associated with farming activities.
• Designing wader landscapes investigates whether breeding densities of waders can be maintained, as farming expands and intensification increases.

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

Whimbrels arrive in Iceland

There is something magical about standing in Eyrarbakki in South Iceland, in spring, watching small flocks of Whimbrel come in over the sea. Thanks to geolocators and satellite tags (about which more later) we know that these amazing waders will have been in the air for around five days, since leaving the west coast of Africa.

Looking down at the seaweed-covered rocks on the morning of 27^th April 2022, we could pick out small groups of new arrivals. Most were resting but one bird was looking for crabs, just as it had been doing in West Africa just a few days previously. A few birds headed off inland while we were watching, making the distinctive seven-note whistle as they left. It sounded almost like a cry of “made it”!

Incoming Whimbrel: Tómas Gunnarsson

Setting the scene

We had been here before. On 22^nd April 2008, I did a live broadcast for the BBC Radio 4 programme World on the Move from this very spot, when I described visible migration to Brett Westwood. On that day, we could see Purple Sandpipers and Turnstone feeding on the tide edge, White Wagtails and Meadow Pipits, newly arrived from Iberia, and small flocks of Golden Plover flying in low over the sea. During the programme, a gaggle of 35 Pink-footed Geese flew in strongly from Britain, as did four Arctic Skuas that had spent winter in the Southern Hemisphere. You can listen to the programme HERE.

On 27^th April 2022, the skies were not as busy as they had been fourteen years previously. High pressure over the British Isles and northerly winds across the Atlantic seemed largely to have pressed ‘pause’ on migration from Britain & Ireland. There were small numbers of newly-arrived White Wagtails, Meadow Pipits and Black-headed Gulls feeding on insects emerging from the banks of rotting seaweed, but the stars were definitely the Whimbrel.

These banks of seaweed will be even more important in May, when there will be hundreds of waders refuelling for the next leg of their journeys, with Sanderling and Dunlin on their way to Greenland and some Knot and Turnstone perhaps flying as far as northeast Canada. When the tide is high enough to wash maggots out of the seaweed, you can sometimes see Red-necked Phalaropes along the tide-line, spinning around and picking food off the surface of the water.

Whimbrel migration

We knew that the Whimbrel were on their way because Global Flyway Network had published a map showing the location of ‘Acuno’, a bird wearing a satellite tag that was put on in the Bijagós archipelago of Guinea Bissau. It had been logged west and north of Ireland on the previous evening, already 6000 km and 4 days into its migration. Doing the sums, it seems unlikely that it could have reached Eyrarbakki by the time that we were there but perhaps it flew past soon after, sending signals back to mission control that would confirm arrival**.

** An hour after I published this blog, Acuno was found to have diverted to the Faeroes. It may breed there – as many Whimbrel do – or if could have run out of fuel and landed there, to put on some extra grammes of fat. We’ll see whether it resumes migration.

** Three weeks later, Acuno flew to Iceland. How much will it have been disadvantaged by giving up on direct flight?

Only a minority of Whimbrel fly straight from Africa to Iceland in spring although almost all fly directly south in the late summer. Most individuals spend late April and early May in Ireland, the UK or on the west coast of mainland Europe. Ireland is by far the most important staging area. The individuals on Eyrarbakki beach may have been tired but there could be advantages to being an early bird. See Time to nest again? based on a paper by Morrison et al.

There are several WaderTales blogs about Icelandic Whimbrels:

Whimbrels on the move summarised the movements of Icelandic birds, based on reports of ringed and colour-ringed individuals. In the paper upon which the blog was based (Gunnarsson & Guðmundsson) there was a strong suggestion that birds only stop off in Britain & Ireland on the way north. Geolocator-based research by Alves et al showed that at least some birds were flying straight from Iceland to West Africa and that these sea-crossings could be very rapid.

Migrations to and from Africa were investigated further in a paper by Camilo Carneiro et al that was summarised in Iceland to Africa, non-stop. More recently, papers by the same team have shown that the most consistent point of the annual migration story is departure from Africa and discussed the links between weather and phenology. These two papers have appeared as the WaderTales blogs – Whimbrel: time to leave and A Rhapsody of Whimbrel.

The latest blog about this research is Winter conditions for Whimbrel, based on a paper that assesses the influence of winter conditions on subsequent breeding performance.

Searching for Black-tailed Godwits

We had seen a flock of eight Whimbrel, earlier in the morning, when we were checking fields for colour-ringed Black-tailed Godwits. The Whimbrel were gliding into land, about five km from the coast, before seeming to melt into a patch of rough grassland, bleached after winter frosts.

We did not pay the Whimbrel much attention as, on the other side of the road, there were Black-tailed Godwits probing for worms in silage fields that were already green, after a few days of warmth and the liberal addition of fertilizer. This is our target species during spring trips to Iceland. We have discovered that the arrival time of individuals is remarkably consistent from year to year, which initially seemed surprising, given that migration appears to be getting earlier. There is more about this in Why is spring migration getting earlier? based on a paper in Proceedings of the Royal Society B.

One of the fascinating things about visiting Iceland is that no two years are the same. 2022 has been a dry, warm spring, with northerly winds potentially delaying migration from Britain and Ireland, as mentioned earlier. Early-arriving Black-tailed Godwits that were wearing colour-rings were birds that winter in Portugal and France and migrate via the Netherlands. There was a period of helpful winds for these early birds that fly further but get to Iceland earlier. This strategy is discussed in the blog Overtaking on Migration, based on a paper in Oikos.

Looking forwards

The short Icelandic summer provides fantastic conditions for these waders to raise their chicks, although there are concerns as to how agricultural development, increased forestry and infrastructures will affect these species in the future. In June, in just two months’ time, adults will cross the Atlantic. Black-tailed Godwits head for the British Isles and the west coast of continental Europe and Whimbrel will return to West Africa. By August, the next generation will be preparing for the journey south and we will be here in future springs to monitor their return to Iceland.

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

Winter conditions for Whimbrel

Up until relatively recently, it was hard to study the same population of migratory waders in both its breeding area and its wintering grounds. Ringed birds established links between different countries but to follow a group of individuals through a complete annual cycle was nearly impossible. Geolocators, and more recently satellite tracking, are starting to enable scientists to piece together whole stories.

Camilo Carneiro and colleagues from the University of Aveiro in Portugal (Dep. Biology & CESAM) and the University of Iceland (South Iceland Research Centre) have been tracking Whimbrel travelling between Iceland and Africa for nearly ten years, using geolocators. In the latest paper to come out of this research they investigated carry-over effects; do conditions experienced in wintering locations affect breeding success?

How might carry-over effects work?

The conditions experienced during one stage of a migrant’s annual cycle may affect their performance in subsequent stages. Perhaps the resources available at a wintering site might affect the timing of spring departure and whether an individual has to stop off to refuel? In turn, such individual differences may be apparent in individuals’ arrival dates in the breeding area, and the condition they are in might affect laying date, clutch size, egg weight, etc?

Icelandic Whimbrel spend the wintering season anywhere between south-west Europe and the tropical coastal areas of West African countries such as Benin and Togo. Despite this huge non-breeding range, individuals are highly philopatric, travelling between the same breeding area and the same restricted wintering site on an annual basis, perhaps for twenty or more years. A Whimbrel flying to the Bijagós Archipelago of Guinea-Bissau covers nearly 6000 km, in the autumn, whereas a bird that only travels to the Tejo (Tagus) Estuary of Portugal flies not much more than half as far (see map). The ‘winter’ conditions they experience are completely different; short temperate days in Portugal or tropical heat in the mangroves in Guinea Bissau.

Camilo and colleagues were able to study Whimbrel in different wintering locations, in order to understand the conditions that are experienced by breeding birds from these areas. They measured annual return rates for birds that had flown different distances and experienced different conditions in the non-breeding season. Do Tejo birds, spending the non-breeding season in the coldest part of the wintering range, have a lower apparent chance of survival? Do those that make it through a Portuguese winter return to Iceland earlier and thereby increase their chance of breeding successfully?

Life on the wintering grounds

Camilo Carneiro has studied wintering Whimbrel in three sites – the Tejo Estuary (Portugal), the Banc d’Arguin (Mauritania) and the Bijagós Archipelago (Guinea-Bissau). Birds in the three sites experience very different conditions between the start of September and the end of March, as discussed in the paper and illustrated in the table below.

Hundreds of observations of individual Whimbrel and flocks provided information on feeding rates, diet and foraging time. Comparable food items were collected from the mud/sand substrates and the energetic values were calculated in the laboratory. Together, these data enabled a calculation of energetic intake. The Net Energetic Intake Rate varied markedly. The figure for the Bijagós is 3.9 times that of the Tejo and 1.4 times that of the Banc d’Arguin.

Crabs provide a large part of a Whimbrel’s winter diet

Birds have a basic running cost – the Basal Metabolic Rate – which is related to the size of the individual and ambient conditions it experiences. Those wintering in areas where they experience periods of colder and windier weather lose more heat and hence need more energy. The BMR was calculated as 2.17, 2.29 and 2.51 Watts for individuals wintering in the Bijagós, Banc d’Arguin and Tejo, respectively, showing that there are higher ‘running costs’ in northern sites. Whimbrels in the Bijagós never incurred energetic costs above BMR, whereas those in the Banc d’Arguin and Tejo had additional energetic costs on 20.6% and 9.7% of the winter days, respectively.

The daily energetic balance differed hugely. Whimbrels in the Bijagós experiencing an average energetic surplus of about 700 kJ/day, followed by 420 kJ/day in Banc d’Arguin and just 11 kJ/day in the Tejo. It should be noted that these figures are based only on day-time feeding.

A colour-ringed bird hiding in a Bijagós flock

Returning to Iceland

The research team has shown that Whimbrel can either fly directly to Iceland or stop off and refuel. It is thought that between 80% and 90% of journeys include a stop-over, typically in Ireland or western Britain. Direct flight takes four or five days. (see summary of previous papers and blogs below).

Whimbrels arrive back in Iceland between the end of April and late May, quickly taking up territories unless there is snow cover. Regular visits to the main study area in the Southern Lowlands helped to ascertain which colour-ringed birds had returned when. Nests are found, and eggs are measured and ‘floated’, to estimate the laying date.

During incubation, attempts were made to catch marked individuals that were carrying leg-mounted geolocators. Adults trapped on the nest are measured, unringed birds are marked and three to five feathers are removed from the breast. These feathers will have been grown in the bird’s wintering area and carry an isotopic signature from that region.

Using stable isotope analyses of the breast feathers, ground-truthed by birds tracked using geolocators, Camilo managed to assign the winter location to 180 Whimbrels. 159 had flown from the tropical region (which includes Bijagós), while 20 had spent the winter in the arid region (which includes Banc d’Arguin) and one in the temperate region (Tejo). When linking the wintering region to breeding phenology and investment, the research team found that:  

• There were no differences in the size of the birds returning from the tropical and arid regions.
• There was no difference between the probabilities of a bird successfully returning from the tropical and arid regions.
• The timing of nesting and the volume of the eggs that were laid by females was not different for birds from the tropical and arid regions.

Where to spend winter?

Only one marked bird definitely wintered in temperate southwest Europe, which is not surprising given that there are not large flocks of Whimbrel in the estuaries of this area. This bird was excluded from the analyses but we know that it will have travelled much less far than birds wintering in Africa and experienced winter conditions in which it could barely meet its daily energy requirements.

Individuals wintering in the arid region, including birds in the Banc d’Arguin, travelled a lot further than birds wintering in southwest Europe. These birds had an expected surplus of 420 kJ per day on an average day but strong winds meant that there were 20% of winter days in which conditions were sub-optimal.

Trying to find Whimbrel in a sandstorm in Banc d’Arguin

Individuals wintering in the Tropical group, including birds in the Bijagós, travelled 900 km further than the Arid group but found more predictable weather conditions, achieving an estimated spare energy capacity of 700 kJ per day, without days with energetic costs above BMR. The authors point out that this energy surplus will likely be needed during long periods of moult and to fuel spring migration.

The authors conclude that any costs associated with having to fly further to reach the tropical region are compensated for by benign conditions. This does not mean that an individual bird makes a choice between Tejo, Banc d’Arguin and Bijagós. Happenstance may determine where a juvenile ends up in its first winter and philopatry means that, if alive, it continues to spend subsequent winters in the same area. Presumably the risks incurred by flying further (to Bijagós) balance out the risks incurred by wintering in a less predictable environment.

Life in and amongst the mangroves of the Bijagós

Very few Whimbrel spend the winter on the Tejo, in Portugal, and calculations in the paper suggest that there is a high risk of not being able to find enough food. This would probably translate into high mortality and explain low numbers.

Carry-over Effects

Although no carry-over effects were found, the authors discuss ways in which they may show up in other traits. There is an interesting discussion as to how carry-over effects might link experiences in the wintering grounds to breeding output in the next breeding season. Amongst other things, the authors suggest that differences among individuals using different wintering sites may only become evident if assessed over several years. We know that conditions are less benign in Banc d’Arguin, for instance. Perhaps there are years when conditions are bad enough for long enough to influence survival or body condition in spring. In such a year, there could be impacts on the ability to migrate, an increased likelihood of dying during migration or delayed breeding. It is possible that longer-term studies will pick up differences in return rates and/or breeding success for birds wintering in different areas? We shall see.

Paper

Linking range-wide energetic trade-offs to breeding performance in a long-distance migrant Camilo Carneiro, Tómas G. Gunnarsson, Verónica Méndez, Amadeu M.V.M. Soares & José A. Alves

Previous research on Icelandic Whimbrel

This Whimbrel, photographed in Bijagós is wearing colour-rings that were fitted in Iceland

Whimbrels on the move summarised the movements of Icelandic birds, based on reports of ringed and colour-ringed individuals. In the paper upon which the blog was based (Gunnarsson & Guðmundsson) there was a strong suggestion that birds only stop off in Britain & Ireland on the way north. Geolocator-based research by Alves et al showed that at least some birds were flying straight from Iceland to West Africa and that these sea-crossings could be very rapid.

Migrations to and from Africa were investigated further in a paper by Camilo Carneiro et al that was summarised in Iceland to Africa, non-stop. More recently, papers by the same team have shown that the most consistent point of the annual migration story is departure from Africa and discussed the links between weather and phenology. These two papers have appeared as the WaderTales blogs – Whimbrel: time to leave and A Rhapsody of Whimbrel.

Further reading

The following WaderTales blogs all consider how migratory behaviour might affect breeding season success, although without the direct measurements for individuals that have been carried out in the Whimbrel study.

Overtaking on migration shows that potential costs of migrating further can be overcome by undertaking early spring migration to staging sites that are closer to breeding areas.

Travel advice for Sanderling summarises research to understand the pros and cons of spending the non-breeding season in widely different locations.

Gap years for sandpipers is based upon a Peruvian Semipalmated Sandpiper paper that investigates the survival advantage of not migrating north to breed in a particular year.

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

A Rhapsody of Whimbrel

Around the globe, the seven-note whistle of the Whimbrel is a spring theme tune for shorebird migration. Where are flocks going to, as they gain height and head north in March, April and May, and why have birds chosen that particular moment to depart?

In a paper in Frontiers in Ecology & Evolution, Camilo Carneiro, Tómas Gunnarsson and José Alves analyse individual migration tracks of birds flying from West Africa to Iceland, including journeys made in successive springs by birds that have been part of the same study for several years. Can these birds help to explain how Whimbrel use time and weather cues in their travel ‘planning’ and might their plans change during the course of their lives?

Look up to the skies and see

Almost all of the Whimbrel that nest in Iceland migrate to West Africa after the breeding season, with just a tiny number wintering in Europe.

• Results from bird ringing suggested that return migration in spring from West Africa to Iceland often involves stop-overs in Ireland or Britain, as well as on the Atlantic coast of mainland Europe. See Whimbrels on the move and the paper Migration and non-breeding distribution of Icelandic Whimbrels.
• This pattern was confirmed using geolocators. The autumn journey south is nearly always direct but 80% of flights from West Africa to Iceland involve stop-overs. See Iceland to Africa non-stop and the paper Faster migration in autumn than spring.
• By looking at repeat tracks for the same individuals, it became possible to investigate the timing of events during a Whimbrel’s annual calendar. The most obvious fixed point in the year was departure time from West Africa in the spring. See Whimbrel: time to leave and the paper Why are Whimbrel not advancing their arrival dates into Iceland?

Life has just begun

The Whimbrel’s story starts in Southern Iceland. It would be great to tag chicks when they hatch, in order to learn what happens to juveniles in their first autumn, as they head south without parental guidance. For the moment, however, Camilo Carneiro, José Alves and Tómas Gunnarsson are focusing on parent birds which they have been catching on their nests since 2012.

The research summarised in the paper at the heart of this blog uses data from 66 retrieved geolocators that have been carried by a total of 39 individuals.  Light data, temperature readings, conductivity and the timing of contacts with water all help to determine the start and end points of individual flights.

Any way the wind blows?

As the authors write in the summary of the paper, “Weather conditions are important during migration, particularly wind and temperature, and can play a crucial role in the timing of events during the annual cycle of migratory birds.” Camilo and his colleagues have investigated how wind conditions, temperature and spring departure date may drive individuals to pursue either a ‘stop-over’ or ‘direct flight’ strategy in the spring. They suggest that one or two of the following scenarios might be envisaged:

Competition on the breeding grounds can be quite vigorous

• Whimbrels may make migratory decisions prior to departure, given local weather conditions. If migratory behaviour is defined prior to departure then that would suggest that departure time from West Africa may not be associated with the wind conditions that can assist individuals on the first stage of their journeys.
• Whimbrels may adjust migratory behaviour during flight, depending on conditions experienced en route. As birds fly north, from 37°N (level with the Mediterranean) to 50°N (SW tip of England), they can make decisions to stop off, rather than continue straight to Iceland. Potentially, they could assess the amount of support they have been receiving from favourable winds and assess the positive effect on fuel reserves. Temperature could also act a cue to weather conditions in Iceland.

Little high, little low

Wader biologists and birdwatchers will have seen flocks of waders preparing for departure from breeding, stop-over and wintering locations.  Birds become restless and groups of birds start to circle and rise into the sky.  The first, departing flock may be joined by others, taking off in small groups to catch up with birds that seem to have a plan. At the same time, birds can also be seen dropping out of the flock to wait for another day.

Once formed, a migratory flock will be made up of individuals that may be heading for points that are hundreds or (for some species) even thousands of kilometres apart but will fly together for this next leg of the journey.

Tómas Gunnarsson has seen Whimbrel circling and gaining height at departure from the south coast of Iceland in autumn, suggesting that they may assess wind conditions at different altitudes before making a final decision and setting their course south. It seems plausible that the same sort of thing might happen during spring migration from West Africa. At some stage, with a large number of tracked birds, perhaps it will be possible to study if waders sample wind speed and direction prior to departure and whether decisions made at this point affect the amount of support they receive from wind conditions when on migration. There’s a great paper about how wind affects the migration of much larger Honey Buzzards by Wouter Vansteelant.

Once in the air, birds in a migrating flock can be impeded by headwinds, assisted by tailwinds and pushed laterally by crosswinds. As has been shown when tracking trans-Pacific journeys of Bar-tailed Godwits, storms and pressure systems can provide a sling-shot effect to accelerate progress, cause birds to temporarily abort their journeys or even back-track a thousand kilometres, in order to refuel for another migration attempt.

Nothing really matters

Camilo and his colleagues compared 9 direct flights with 48 that included stops in Portugal, France, Ireland and north-west Britain. Birds that departed later tended to undertake direct flights. Interestingly, they found little evidence that conditions were linked to an individual’s migration option:

• For individuals undertaking either direct flights or stopovers, the wind conditions at departure did not differ from winds during the previous seven days, suggesting little or no selection for wind conditions to initiate the flight.
• Individuals on direct flights encountered similar winds as they passed through the region 37°N to 50°N (Mediterranean to SW tip of England) as those on stop-over journeys.

Too late, my time has come?

For late-departing birds that fly straight to Iceland, there is the potential to catch up with (and even overtake) birds that left earlier and subsequently stopped in countries such as Ireland. In such circumstances, one could imagine that birds still in West Africa in late spring may ‘opt’ for a direct flight. However, the wind patterns over a period of seven days prior to departure were no different to the ones at the start of a non-stop flight. There did not seem to be any weather-related reason for these birds delaying departure as long as they did.

Camilo Carneiro is also investigating the breeding success associated with different arrival times and migration patterns

For birds that do stop-off en route in Britain and Ireland, which are relatively close to the breeding sites in Iceland, there are potential benefits, as discussed in more detail in the paper:

• Individuals might be able to assess (remotely) the weather conditions at their breeding sites if there are links between weather patterns in Iceland and those in Ireland and western Britain. If this is the case, then they can adjust the start of the final Atlantic crossing so as to arrive in Iceland when conditions are likely to be favourable.
• Whimbrels can feed up in Britain & Ireland, potentially arriving in Iceland in better condition than birds that have flown directly from West Africa.

Carry on, carry on

The fascinating thing about being able to track individuals is that we are starting to understand the conditions that may lead to the migration patterns we see at the population level. In other WaderTales blogs, some of the key processes and patterns have already been discussed:

• Potentially, arriving in breeding areas early may confer advantages which can be explained by the ability to nest again if a first attempt fails. See Time to nest again? based on the paper Why do earlier-arriving migratory birds have better breeding success?
• The timing of migration is driven by new generations, rather than by individuals changing what they do. See Generational Change based upon Mechanisms driving phenological change in migratory species.
• Birds can make up for the ‘disadvantage’ of flying further south if they make an early spring movement to a staging area closer to their breeding grounds. See Overtaking on migration and the similarly titled paper.
• Once birds are locked into a particular pattern of migratory timings they stick with them – they don’t know that there are better options. See Travel advice for Sanderling based upon Low fitness at low latitudes.

Given this body of knowledge, suggesting little flexibility once an individual’s phenology is fixed, one might expect that an individual Whimbrel, travelling from West Africa to Iceland, would adopt the same migration pattern in subsequent years. Tagged Whimbrels, for which there were repeat migration tracks, mostly ‘did the same’ but not always.

Any way the wind blows, doesn’t really matter

The key finding of Camilo Carneiro and his colleagues is that weather conditions are not the main driver of different spring migratory timings in Icelandic whimbrels. As suggested in Whimbrel: time to leave (and the paper Why are Whimbrel not advancing their arrival dates into Iceland?) departure from West Africa is the most firmly scheduled point in a Whimbrel’s annual cycle. However, three birds provide an opportunity to build a modified hypothesis.

In the course of this study of Icelandic Whimbrel, thirteen birds have provided multiple years of data and there have been three cases in which birds have switched migratory behaviour, seemingly contradicting the ‘birds always do the same thing’ theory. In each case, individuals changed from ‘direct-flight’ to ‘stop-over’ and, having changed, they then repeated the ‘stop-over’ option. The fact that all three individuals made the same change hints towards individual refinement of behaviour. Since there appears to be no clear advantage to direct migration, perhaps individuals are moving to a two-stage migration when they discover that this is a possibility?

Is this just fantasy?

This is where the paper stops but it will be fascinating if the research can continue:

• Are changes always going to be in the same direction – from ‘direct-flight’ to ‘stop-over’?
• Most juveniles are thought to fly directly to West Africa. By tracking young birds, caught in Iceland prior to departure, perhaps it will be possible to work out the proportion of first journeys that are direct?
• Young birds that fly south across the Atlantic will not have learnt that there is any land between Iceland and West Africa. Do they retrace their journeys when they fly north again, eighteen months later?
• What proportion of these birds that start on the ‘direct-flight’ strategy later switch to ‘stop-over’?
• If some juveniles stop off in western Europe, on their first journeys south, perhaps these birds also stop off on their first journeys north? That might mean that they never used the ‘direct-flight’ option.
• And how do flocks work? Will it ever be possible to deploy enough trackers to see whether ‘direct-flight’ individuals learn that there’s an alternative option by travelling in flocks with birds that use the ‘stop-over’ strategy.

It’s all fascinating stuff about the Queen of waders!

Anyone can see

The paper featured in this blog is: Linking weather and phenology to stopover dynamics of a long-distance migrant by Camilo Carneiro, Tómas G. Gunnarsson & José A. Alves, published in Frontiers in Ecology & Evolution.

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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

Where to nest?

There 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

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.

Iceland: a wader factory

As 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).

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.

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.).

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.

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.

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

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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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

THIS BLOG HAS BEEN UPDATED

Birds of Conservation Concern 5 (published on 1 Dec 2021) saw the promotion of Dunlin and Purple Sandpiper to the Red List.

Please click here to switch to: Eleven waders on the UK Red List

If 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.

In 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

“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

“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

“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. See also Scotland’s Dotterel: still hanging on.

Whimbrel

“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 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

“… 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.

• Is the Curlew really near-threatened?
• Curlews can’s wait for a treatment plan
• Ireland’s Curlew Crisis
• More Curlew chicks needed

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

Black-tailed Godwit

“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

“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

“… 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

“… 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 GWCT emphasise the importance of reducing current pressures on British birds.

In conclusion

The 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.

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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.