Conservation beyond boundaries

April 7, 2023April 10, 2023 / Graham Appleton / 4 Comments

When an environmental impact assessment concludes that only a small number of shorebirds will be affected by a new airport, because relatively small flocks are counted during field surveys, is there an assumption that the birds encountered are always the same individuals? What if different shorebirds use the same patch of mud at different stages of the tide, at different times of day or in different seasons? How many birds might really be affected?

In a 2023 paper in Animal Conservation, Josh Nightingale and colleagues investigate the movements of colour-marked Black-tailed Godwits, to see how much they fly into, out of and around a Special Protection Area, to work out how well an Environmental Impact Assessments (EIA) might assess the importance of a site that has been scheduled for development. They call for more use to be made of movement data, to assess the total impact of new developments proposed for estuaries and elsewhere.

Impact assessments

The pressures on estuaries have never been greater, as humans turn to them for transport, food, energy and to create land for new developments, such as airports. These muddy havens might be protected by national and international statutes but legally-enforceable conservation designations tend to melt away when there is money to be made, as discussed in Tagus Estuary: for birds or planes?

Developers often argue that they only want to use a small area; taking a bite out of an estuary may seem to affect only 10% (for instance) of a Protected Area – and leave 90%. Counting the birds that use that particular section might show whether this ‘10%’ contains more or fewer birds than expected and indicate whether an unacceptably high proportion of the species for which the Protected Area was designated might be affected. How much more can be learnt if we consider movements that take place within an estuary, the waves of birds that use the estuary in different seasons, the importance of the site within a Flyway and linkages to breeding areas?

Thanks to ringing and colour-ringing, we know that Protected Areas can form networks of sites used by individuals. For example, an islandica Black-tailed Godwit might moult on the Wash (Eastern England), spend the winter on the Tagus (Portugal) and spring in Morecambe Bay (Northwest England). Thousands of limosa Black-tailed Godwits that winter in West Africa spend two months in the Tagus in spring, where they will be seen alongside Grey Plovers from Siberia, Turnstones from Canada and Bar-tailed Godwits from the Arctic regions of Scandinavia. Our knowledge of the strength and complexities of these networks is deepening, still further, thanks to satellite tracking, and the same technology provides the potential to understand more about within-estuary movements too.

Network Analysis

*Josh Nightingale measures a Black-tailed Godwit* *with the Tagus Estuary Ringing Group*

Information on movements of individual birds, generated by ringing, together with the development of methods such as network analysis, provides a framework in which researchers can assess the importance of Protected Areas – or threatened parts of Protected Areas. Network analysis is the study of connections. In this context, a network is simply a collection of sites, dubbed nodes, linked by connections known as edges, which may have varying directions or strengths.

In pictorial terms, ‘thicker’ edges indicate that more birds connect two nodes. When assessing connectivity, the researchers considered the number of other nodes each node is linked to and the variety of pathways between nodes.

Despite being powerful and flexible, network analysis is currently used less by conservation practitioners than by academics, and much of their work is at landscape- or regional-scales. In a 2023 paper, Josh Nightingale and his colleagues adjust the focus, to see how network analysis might explain what is happening within and around a Protected Area – information that is valuable when trying to assess conservation implications of planning decisions. They use movement data to reveal the range of sites used by individuals, and thus the susceptibility of those individuals to a local development.

Network analyses can reveal which sites are most important to population-level connectivity, or the impact on connectivity of losing one or more sites. These results can be combined, to calculate the ‘impact footprint’: how many individuals use the impacted area and how do their movements connect with neighbouring sites (inside or outside the Protected Area). By representing movements between sites in a network, practitioners can gain a more accurate picture of how the effects of a localized impact may be felt at connected sites. This information can then be used to determine whether populations or habitats are impacted, and thus inform policy decisions.

Applying a Network Analysis framework to the Tagus

*Black-tailed Godwits feeding along the shoreline of a built-up area* *in the Tagus estuary*

The Tagus Estuary, on whose banks Lisbon sits, is Portugal’s largest wetland and the country’s most important site for many waterbird species. Part of the estuary is designated under the EU Birds Directive as a Special Protection Area (SPA), with a smaller Ramsar Site at its core. The SPA excludes several of the estuary’s high-tide roosts, which consequently lack legal protection and are vulnerable to development, erosion and other threats.

The Portuguese Environment Agency has issued an Environmental Licence, approving plans to construct an international airport in the heart of the Tagus estuary, on a site overlapping part of the SPA. The Environmental Impact Assessment (EIA), conducted for the development, considers the main threat to bird conservation to be noise disturbance, with an aeroplane taking off or landing every 2.5 minutes and flying at low altitude (<200 m) over the SPA (see article by José Alves in Wader Study). Such disturbance can cause birds to take flight, with consequent increases in daily energy expenditure. The effect can be seen even when the airport has been operational for decades (van der Kolk et al). Airport-related disturbance close to wetlands has been shown to influence the distribution of waterbird communities (Celdrán & Aymerich).

The predicted impact of the Montijo airport development varies, depending upon the threshold of noise sensitivity assumed. Although it has been shown that waterbirds alter their behaviour when subjected to noises above 50 dB(A) (see Wright et al., the study used as a reference for the EIA), the Environmental Licence for Montijo Airport only considers relevant areas impacted by over 65 dB(A). Crucially, movements of birds within, to or from the Protected Area were not considered.

To assess how network analysis might explain the real impact of the airport, Josh Nightingale and his colleagues focused on the Black-tailed Godwit, a species for which the Tagus SPA had been designated and for which a large amount of colour-ring data was available. They wanted to answer these questions:

How much of the local godwit population is protected by the Protected Area during the year, and how much does this overlap with the area to be impacted by development?
How much of the Tagus is used by birds from the Protected Area, and by birds from the area that would be affected by low-flying aircraft?
Which sites are linked most closely to others and how might the predicted development weaken connections between sites across the Tagus estuary?

Assembling the data sets

*Black-tailed Godwit ringed as an adult in Iceland*

Islandica Black-tailed Godwits have been intensively studied since 1993, when the first birds were colour-ringed. The datasets used in these analyses comprise sightings of birds ringed in Iceland, on the Wash (Eastern England) and in the Tagus (Portugal). Sightings of these colour-ringed birds have been reported by thousands of observers across the whole range of the subspecies. To get a flavour of the importance of these reports (and the dedication of birdwatchers) read Godwits and Godwiteers.

Within the Tagus Estuary, the focus was on marked birds reported between 1st January 2000 and 1st July 2020. Observations were recorded at 30 sites that were visited at least once during early and late winter, and more frequently since October 2006. To reduce the potential risk of observation error, only sites at which an individual was recorded at least twice during its lifetime were assigned to that individual.

To assess site-level noise-exposure that birds might experience, Josh Nightingale and colleagues analysed their data based on the areas in which godwits might encounter noise levels of 55 dB(A) and 65 dB(A). Full methods used in the network analysis are given in the paper.

Impacts on Black-tailed Godwits

Individual Black-tailed Godwit are conservative in their habits. At a Flyway scale, they typically use only four or five different sites per year, with this annual schedule remaining constant over up to twenty years (as discussed in Generational Change). Josh Nightingale found similar consistencies within the Tagus Estuary. Most of the 693 individually-tracked godwits were found at six or fewer sites (of the thirty available), even when observed for a decade or more. 82.8% of individual godwits used sites inside the SPA and 67.7% used sites outside the SPA. There was seasonal variation in the protection footprint of the SPA, which was three times as important in October-December as it was in January-March

In the early part of the winter, islandica Black-tailed Godwits are most likely to be found feeding on the estuary itself, with many moving to inland feeding sites, particularly rice fields, in January to March. Much of the area that would be impacted by the noise from aircraft is over the estuary so it is not surprising that the impact footprint is greater in October to December, when disturbance is estimated to affect 68.3% of the godwits, if a threshold of 55 DB(A) is used, or 40.7% based on 65 dB(A).

*Godwits on the intertidal flats of the Tagus estuary*

When the researchers considered individual movements within the same winter, they found that birds from within the Protected Area visited 14 out of 17 of the sites that lie outside the Protected Area. A flock of roosting or feeding birds seen well outside the SPA is very likely to include birds that also feed in the SPA. There were similar levels of connectivity from unimpacted sites across the estuary to the 55 dB(A) impact zone. The most centrally connected site, the Giganta rice fields, is outside the SPA but within the 55 dB(A) affected area – hence unprotected and highly impacted.

*Take off! Part of a flock of thousands of Black-tailed Godwits taking off from a rice field* *in the Tagus estuary*

Turning the focus to the area of the estuary that will be most impacted by aircraft noise, the researchers found that 68% of islandica Black-tailed Godwits in the Tagus will be affected. This is higher than an estimate of between 0.5% to 5.5% that was quoted in the EIA. The lower estimate is based on a 65 dB(A) threshold, rather than 55 dB(A), uses old counts and does not consider bird movements. This implies that the effect of the airport on Black-tailed Godwits will be twenty times as large as considered in planning decisions. And this discrepancy is just for one of the species for which the Tagus is designated as an SPA and Ramsar Site.

The paper contains a detailed analysis of how the protected network would be degraded by the new airport, through loss of key sites and by taking out edges that link current nodes that will be affected by disturbance. Overlaying the 55 dB(A) on the current Tagus network has the potential to reduce connectivity between sites by nearly 30%, effectively partially blocking the free flow of birds around the estuary.

Conservation implications

The footprint approach developed by Josh Nightingale is really neat. For the Tagus, it shows that over half of the colour-marked Black-tailed Godwits use sites outside the Special Protection Area, as currently defined, and that the majority of the most important sites that provide connectivity across the estuary are also unprotected.

Using Black-tailed Godwits as an example, the research team show that the EIA may have underestimated the impact of the airport by a factor of about 20. When disturbed by aircraft or scared off to reduce strike risk, more energy will be expended and some birds may permanently desert key feeding or roosting areas. Research elsewhere has shown that displacements can have temporary and even long-term effects on the survival rates of affected individuals.

To quote from the paper, “Protected Areas are a critically important conservation tool to protect populations, especially as ranges shift in response to climate change. To secure the integrity of PAs and the populations they support, we need to be able to accurately assess the impacts of developments inside and outside PA boundaries. Animal-tracking data offer exciting and feasible opportunities to assess PAs’ contributions to protecting populations of mobile species and the potential for adverse effects of external developments on PA integrity.”

Conservation beyond Boundaries: Using animal movement networks in Protected Area assessment. Josh Nightingale, Jennifer A. Gill, Böðvar Þórisson, Peter M. Potts, Tómas G. Gunnarsson & José A. Alves. Animal Conservation. Doi: 10.1111/acv.12868.

*Black-tailed Godwits moving to roost on the saltmarsh, as the tide covers the mud*

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.

Inland feeding by coastal godwits

November 10, 2022 / Graham Appleton / 2 Comments

Species such as Dunlin and Knot are well-served by conservation measures that aim to protect estuaries but the same is not necessarily true for Black-tailed Godwits. In a 2022 paper in the journal Wader Study, Clément Jourdan and colleagues describe the movements of ten tagged Black-tailed Godwits, showing how much time they spend on poorly-protected inland sites and how the species’ use of these habitats changes over the seasons.

Mobile Black-tailed Godwits

Large numbers of Black-tailed Godwits can be found along the Atlantic coast of France, comprising birds from the booming islandica race and others from the struggling limosa race, with proportions varying throughout year. Some limosa breed in France and head to Africa in autumn but the numbers of this subspecies are dwarfed in autumn and spring, when limosa from the Netherlands and neighbouring countries stop off, to top up their fuel supplies for migration. Adult islandica birds from June/July to April/May and some young islandica stay in France during the summer months too.

This mix of the two races, one of which is increasing (islandica: see From local warming to range expansion) and the other of which is in severe decline (limosa: see Dutch Black-tailed Godwits down by nearly 75%) creates conservation challenges. Hunting of waders is still popular in France and decisions as to which species are legally shot need to be evidence based. Do limosa and islandica mix or are there times of year and circumstances when hunters can be pretty sure that they are targeting only islandica? For the moment, there is a temporary suspension of Black-tailed Godwit (and Curlew) from the quarry list (see Black-tailed Godwit and Curlew in France) while more evidence is collected. Set against this background, it is really important to understanding habitat use by both islandica and limosa.

*Mist nets set to catch Black-tailed Godwits*

Wintering islandica

Icelandic Black-tailed Godwits return to France from June onwards and the last birds do not leave again until the start of May. By analysing the movements of 10 wintering islandica Black-tailed Godwits, using GPS-telemetry, Clément Jourdan and colleagues gained insights into the varied ways in which birds spend their time during this non-breeding period. Although it might look as if Black-tailed Godwits have a wide range of sites at their disposal, each individual only made use of a limited number of options during the course of a winter. The tagged birds moved around at both small and large spatial scales, on tidal and/or daily cycles, and changed their patterns with the seasons.

It was already known that islandica Black-tailed Godwits in France use bare mudflats or seagrass during the autumn, with some individuals using grasslands during the winter, and that most birds migrate to The Netherlands or eastern UK in spring, where they forage primarily on grasslands. This northwards movement, especially to The Netherlands, puts birds in pole position for the flight to Iceland (see Overtaking on migration).

Studies of energy intake rates in godwits feeding on mudflats and grasslands in Eastern England suggested that birds move to grasslands when estuarine food supplies are no longer sufficient to fulfil their energy requirements, and that they frequently use both mudflats and grasslands over the winter and spring (buffer effect paper). Colour-ring studies show that birds tend to use the same sites in the same seasons every year (as discussed in Generational Change). The study of tagged birds in France allowed researchers to add daily detail for a small number of Black-tailed Godwits.

The study was carried out on the French Atlantic coast, from the Loire Estuary area, in the north, through the Baie de Bourgneuf and the Vendée Coast, and south to the Pertuis Charentais area. Full details of available habitats are provided in the paper.

Follow those godwits

The tags on the study birds were set to provide locations every thirty minutes. The ten individuals that are the focus of the Jourdan paper provided a mean of 41 locations per day, rather more than can be obtained from colour-ring reading!

At a large spatial scale, the 10 monitored Black-tailed Godwits could be split into two groups:

Six godwits (BLTG11, 12, 14, 16, 17 and 18) remained within the Pertuis Charentais area throughout their tracked period, exploiting a small number of distinct sites. The average distance travelled in a day varied from 10 km to 31 km, depending on the individual, sometimes exceeding 40 km in one day. These birds were largely coastal, feeding on intertidal areas, but some of them occasionally visited inland habitats around the major roost sites.
Four godwits (BLTG13, 15, 19 and 20) spent the early and mid-winter period in Pertuis Charentais but then flew north, to the Loire-Bourgneuf area, either directly or with a stop at the Olonne Marshes on the Vendée Coast. These refuelling stations were also used during pre-migration and post-migration periods. BLTG13 and BLTG15 were monitored during two successive years and behaved consistently between years. BLTG19 was tagged as a juvenile and, as expected, stayed in France over the course of a full eighteen-month period.

*BLTG13 behaved consistently in two winters*

When it came to habitat use, the authors found it difficult to describe general patterns. This is important; mitigation measures aimed at providing alternative feeding areas tend to focus on the one-size-fits-all principle. In the detail presented in the paper, we see that different birds behave very differently. Wet grassland is not going to be a replacement habitat for a Black-tailed Godwit that specialises on feeding in tidal seagrass beds. Here are a few gems from the paper:

BLTG13 and 15 showed annual consistencies in their habitat selection but behaved very differently to each other. BLTG15 mainly used bare mudflats between August and February and selected inland marshes just before migration and upon return from Iceland. BLTG13 mainly used inland marshes in the run-up to departure (mid-February to mid-May) and upon return, using other habitats (saltpans, coastal marshes and mudflats) during the wintering period (early August to mid-February).
Individual birds switched habitat between three and eight times per month, often using multiple habitats during the course of a single day. Several birds spent long periods focusing on intertidal areas but then roosted on marshes or in saltpans, but even here there were exceptions. Having been part of the mud/marshes group, BLTG14 started prospecting inland to marshes and hunting ponds. This bird was one of two that used hunting ponds more intensively, both by day and by night, after the shooting season closed at the end of January.
Important habitats included inland marshes, hunting ponds and salt pans, with BLTG11 feeding almost exclusively in salt pans and ignoring tidal feeding opportunities. It was also clear that some birds were feeding at night more than had previously been thought.

*BLTG13 and BLTG15 illustrate the different mixes of habitats that are used by individual Black-tailed Godwits*

*One of the tagged birds, breeding in Iceland*

The movements at both local and large scales underlined the use of multiple habitat types, in both marine areas and freshwater wetlands. Most birds predominantly used intertidal areas from early to mid-winter and then moved to inland marshes just before the spring migration period, but they also showed an ability to shift quickly from natural habitats to artificial wetland habitats such as saltpans or hunting ponds.

Looking at the distribution of Black-tailed Godwits across a wide range of habitats, it may be tempting to think that this is a flexible species. Birds certainly seem able to identify new opportunities that become available as the season progresses, such as switching to grassland feeding when estuaries become less productive and then using hunting ponds once duck shooting is over. However, once a bird has adjusted to its own rhythms, it remains faithful to its own patterns of habitat use between years.

Conservation challenges

Many of the estuaries of Europe are protected from further development, at least to some extent, thanks to European legislation but rarely do the boundaries of Important Bird Areas extend beyond beaches and sea walls. As Clément Jourdan and his colleagues show, Black-tailed Godwits commonly use feeding areas that lie outside designated areas, especially during the period when they are fattening up for spring migration. As the authors point out, inland pools can also be important roost sites, as described in A place to roost, which highlights the Gilroy ‘godwit field’ near the Dee Estuary of northwest England. This small site can be used by 5% or more of the Icelandic population of Black-tailed Godwits during high spring tides in early autumn.

The boundaries of estuaries have been defined by the sea walls that protect towns, villages and agricultural land but this is an artificial system. Four centuries ago, waders could move freely between estuaries, brackish lagoons and freshwater marshes. These days, waders such as Black-tailed Godwits fly tens of kilometres to find the mix of habitats they need. Studies of these ten birds add rich detail to the picture painted by colour-ring sightings, as discussed in Godwits and Godwiteers.

The ‘near-threatened’ Curlew is even more of a challenge for conservationists. Curlew spend a lot of their time on estuaries but also use nearby fields and grasslands as roosting and feeding sites. Forth Estuary Curlew that can be seen on rugby pitches in Edinburgh are probably not going to be disturbed more than a few times a week but a new £150 million distribution centre at West Melton in Hull is permanently removing fields used by Humber Estuary birds.

We know that other wader species, such as Golden Plover and Oystercatcher flip backwards and forwards between marine and terrestrial feeding/roosting areas but tracking may well show that such behaviour is more widespread than we thought across species of wader.

Godwits in France

This paper provides fascinating insights into the lives of individual Black-tailed Godwits. There are too few tracked birds for formal analyses of habitat preferences but there are enough differences within the ten individuals to show that the removal of one site from a winter network can have wider implications than might have been expected. The full Wader Study paper is available here:

Combination of marine and freshwater artificial habitats provide wintering Black-tailed Godwits with landscape supplementation. Clément Jourdan, Jérôme Fort, Frédéric Robin, David Pinaud, Philippe Delaporte, Didier Desmots, Alain Gentric, Pamela Lagrange, Julien Gernigon, Loïc Jomat, Pierre Rousseau & Pierrick Bocher. Wader Study. DOI 10.18194/ws.00271

UK waders: “Into the Red”

October 4, 2022October 11, 2022 / Graham Appleton / 4 Comments

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.

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.

Iceland’s waders need a strategic forestry plan

June 18, 2022 / Graham Appleton / 7 Comments

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.

Power-lines and breeding waders

June 9, 2022June 18, 2022 / Graham Appleton / 5 Comments

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 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.

Whimbrels arrive in Iceland

April 27, 2022December 29, 2022 / Graham Appleton / 5 Comments

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”!

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.

England’s Black-tailed Godwits

January 27, 2021 / Graham Appleton / 5 Comments

Back in 1976, all of the UK’s fifty pairs of Black-tailed Godwits were breeding in the Ouse Washes, which cut across the Norfolk/Cambridgeshire border in eastern England. Over the next thirty years, Ouse Washes numbers collapsed and the Nene Washes (near Peterborough) became home to forty or more pairs. What demographic processes were at play that led to this 24 km shift in the population centre and are there lessons to be learnt about the future conservation of England’s limosa Black-tailed Godwits?

43 years of breeding Black-tailed Godwits

The Washes of England represent a westerly extension of the breeding range of limosa Black-tailed Godwits, the focus of which is the Netherlands. This is a subspecies that’s in serious trouble; there has been a 75% decline in the Dutch population, as you can read here. The RSPB has invested in the conservation of Black-tailed Godwits for over forty years, most recently as part of Project Godwit, a partnership with WWT. In a 2021 paper in Wader Study, Mo Verhoeven and colleagues compare detailed studies in the period between 1999 and 2003 with more recent work (2015-2019) to try to understand how changes in demographic rates (productivity, survival and recruitment) have impacted upon the number of breeding pairs.

This study focuses on Black-tailed Godwits on the Low Wash, an area of the Nene Washes that is managed by RSPB. After periods of high rainfall, these areas are flooded to store excess water, mainly in the winter months. Fieldwork during the two periods of intense monitoring (1999-2003 & 2015-2019) included:

Searches for marked birds, when they return in March and April and throughout the breeding season.
Locating nests in April and then following breeding attempts (measuring and weighing eggs, to back-calculate to lay-dates, and monitoring nesting success).
Ringing and colour-marking chicks.
Nest data loggers and cameras were used in the later period (2015-2019), to help establish timing of predation events.
Adults were trapped on the nest (2015-2019), to add rings, colour-marks and, in some cases, geolocators.

The switch to The Nene

Back in 1975, all of the limosa Black-tailed Godwits nesting in the UK were to be found in the Ouse Washes. The graph below shows the number of pairs nesting in the Ouse and Nene Washes, together with other regions of England. The two study periods (1999-2003 & 2015-2019) are highlighted. In 1999, at the start of the first period of intensive study, over half of pairs were in the Nene Washes, with a rapid increase in this proportion by 2003. The situation remained relatively stable through to the start of the second period of intensive study in 2015.

The graph showing the number of breeding pairs only runs through until 2017, as the number of breeding pairs in 2018 and more recent years has been affected by head-starting, the process of hatching chicks in incubators and raising them in captivity, through to fledging. The WaderTales blog Special Black-tailed Godwits describes the excitement and anticipation as the first 25 captive-reared chicks were released at the Ouse Washes. The first head-started birds returned in 2018.

*Black-tailed Godwit chick being raised in captivity*

In 1992, following multiple years of spring flooding at the Ouse Washes, the godwit population in the UK declined to only 19 pairs. There was a steady increase of godwits at the nearby Nene Washes and the UK population recovered to 53 pairs by 2006. Since then, the breeding population at the Nene Washes had been slowly declining until head-starting provided a welcome boost. See Head-starting Success and reports on the Project Godwit website.

Comparing the two periods

The early period of intensive work in the Nene Washes (1999-2003) took place when the population was increasing strongly, a trend that continued until 2006. The later period (2015-2019) coincided with a shallow decline. For conservationists, keen to maintain a UK population of breeding Black-tailed Godwits, it is important to understand the causes of the differences in population trends, if the right conservation solutions are to be deployed to resolve ongoing problems for this red-listed wader.

Adult survival: Large waders, such as Black-tailed Godwits, are long-lived birds (see Measuring Shorebird Survival) and it is unsurprising that the annual survival rate of Black-tailed Godwits nesting in the Nene Washes was found to be high, with an estimate of 88%. The short period of time available between ringing and potential observations for birds that were marked in the second period (2015-2019) meant that there were fewer sightings from which to calculate survival rates of birds from this recent period. Despite this smaller sample, the research team are confident that adult survival has not declined over time and is therefore not the cause of the change in population trend between the two periods.

*This chick weighs 30.6 grammes (just over an ounce)*

Nest Survival: The number of nests lost to flooding was very low indeed; none in the earlier period and only 1% in the later. Nest desertion rates were higher in the more recent period (7%) than during 1999-2003 (2%) but the differences are not statistically significant. The big change is in predation rates. Only 22% of the nests that failed in the period 1999-2003 failed due to predation but this more than doubled in 2015-2019. Analyses that took account of lay-date showed that the chance of hatching was much lower in 2015-2019 than in 1999-2003, irrespective of the timing of nesting attempts.

Chick survival: Given the increased predation of nests, it is perhaps unsurprising that the chick survival rates were also lower in 2015-2019 than in 1999-2003. Modelling suggests that a Black-tailed Godwit chick that hatched in one of the summers between 1999 and 2003 was between 2.4 and 3.6 times as likely to survive the first fourteen days of life as a chick that hatched between 2015 and 2019.

Explaining the patterns

The Ouse and Nene Washes are only 24 km apart but adults are highly site-faithful, and it is therefore likely that birds will try to nest in the same place in consecutive years, if at all possible. The Ouse Washes population was not marked at the time of the flooding events in the springs of the 1990s, so we do not know whether the growth in numbers on the Nene during this period was linked to flood-related declines on the Ouse. However, we do know that, when water levels are too high at either the Ouse or the Nene Washes, pairs will nest on nearby arable fields, just outside the flood plain. Nests on arable fields at the Nene have never resulted in successful fledging, so any such attempts near the Ouse in the 1990s may well have gone unnoticed.

As discussed in Site fidelity in Black-tailed Godwits, chicks are also highly philopatric (tending to return to the site from which they fledged). Of the 63 chicks raised on the Nene Washes, for which subsequent breeding locations have been ascertained, 61 have been found breeding in their natal area. This is the same pattern as found in the Dutch breeding areas. It is likely that the growth in numbers in the Nene Washes in the period 1977 to 2006 was driven by high productivity and subsequent local recruitment. The key question is therefore ‘why has breeding success declined since this time?’

Some causes of reduced breeding success can be ruled out. None of the 213 nests was trampled by grazing cattle (see Big Foot and the Redshank nest) and only one nest was flooded. This leaves predation as the main cause of low success. The authors suggest three things that might have changed:

Lower numbers of other waders: Over half of the other waders nesting in the Nene Washes study area disappeared between 2000 and 2016, with losses of 73% of breeding Lapwing, 46% of Redshank and 49% of Snipe. The number of Black-tailed Godwit nests increased during this period. These four species all work together to raise the alarm if a predator is present and to mob mammalian predators such as fox and stoat. Reduced overall wader numbers could have reduced predator deterrence and will certainly have meant that there were fewer nests of other waders for predators to find.

Reduction in non-wader prey: The number of Pheasants in the area surrounding the Nene Washes is thought to have decreased, with reductions in the numbers released for shooting. Fewer pheasants around during the breeding season may result in a reduction in the availability of Pheasant eggs, sitting females and chicks. The lack of this food could have increased predator pressure on breeding waders.

Broader suite of predators: Badgers, Common Buzzards and Red Kites have colonised the area and Marsh Harrier numbers have increased. Badgers are known to target ground-nesting birds and avian predators take eggs, chicks and occasional adults.

What to do next?

*Head-started chicks in the Project Godwit release cage*

The head-starting project has been designed to give a short-term boost to numbers of breeding Black-tailed Godwits on the Ouse and Nene Washes. In the longer term, Project Godwit aims to improve habitat management in ways that can lead to increased productivity, without head-starting. The authors identify several actions to try to increase productivity, which include:

Maintain the openness of the wader nesting area, by removing trees, reed beds and rushes, in which predators can perch, nest and hide (there’s more about this in Mastering Lapwing conservation).
Attempt to increase the abundance of alternative prey (small mammals) in the surrounding landscape (see Can habitat management rescue Lapwing populations?).
Provide diversionary food for key avian predators (see Deterring birds of prey).
Use a mixture of fences and predator control (see Toolkit for wader conservation).
Flood the grassland in the winter period, to reduce numbers of small mustelids (stoats and weasels) in the godwit nesting areas and concentrate small mammal prey (e.g. mice and voles) on the edges of the Nene Washes.

Some additional thoughts (not in the paper)

The growth in the Nene Washes population of Black-tailed Godwit between 1977 and 2006 suggests that Black-tailed Godwits can do well in the right circumstances. Perhaps there are other areas of lowland wet grassland – especially ones with low predator densities or effective predator management – in which head-started individuals might thrive?

An annual survival rate of 88% means that only about one in eight adults dies in a given year. If survival rates change then that can have a major effect on the viability of a small population. The reliance of limosa Black-tailed Godwits upon a limited number of habitats and key sites in the non-breeding season, especially in Portugal, Spain and Senegal, make them very vulnerable to changes, whether brought about by climate, new farming systems (especially rice growing) or habitat removal (see blog about planned airport in Tagus estuary. The conservation of limosa Black-tailed Godwits is a flyway-scale challenge, as outlined in this action plan, produced by AEWA.

Read more

Diagnosing the recent population decline of Black-tailed Godwits in the United Kingdom. Mo A. Verhoeven, Jennifer Smart, Charlie Kitchin, Sabine Schmit, Mark Whiffin, Malcolm Burgessand Norman Ratcliffe. Wader Study.

This study was jointly funded by the RSPB and Natural England through the Action for Birds in England Partnership and through an EU LIFE Nature Programme project (LIFE15 NAT/UK/00753 – LIFE Blackwit UK) in partnership with the Wildfowl & Wetlands Trust with support from the National Lottery Heritage Fund via the Back from the Brink Programme.

Cycling for waders

August 7, 2020December 5, 2020 / Graham Appleton / 2 Comments

This blog is mostly about Black-tailed Godwits but there’s stuff about cycling too!

If you’re a Black-tailed Godwit, a 2800-mile (4500-km) direct flight from East Anglia to West Africa is estimated to burn 1085 Calories (4500 kJ) of energy (Alves & Lourenço). Fuelled by Cambridgeshire worms, a female godwit that was raised by the Project Godwit head-starting team flew from the Nene Washes to wetlands in south-east Mauritania in just two days. ‘Cornelia’ – as she was named – undertook this marathon journey with no pre-season training. She just took off on 13th August and arrived on the 15th.

To raise money for Project Godwit and for research projects funded by the International Wader Study Group, Jen and Mark Smart cycled from Somerset to East Anglia, on a 600 mile (960 km) journey that links sites that have been visited by head-started Black-tailed Godwit chicks. Each of them burnt 15,000 Calories (62,800 kJ) over the course of eight days, taking in high energy foods as they travel and stopping to feed and rest each night. Unlike Cornelia, Mark and Jen had been training for years.

Quick reminder of head-starting

Black-tailed Godwits breeding in East Anglia face huge challenges, as you can read below. Four years ago, their situation had become so perilous that it was decided that the only way to stop them disappearing completely was to hatch eggs in incubators and raise chicks in captivity. You can read more about head-starting here. Project Godwit is a partnership between RSPB and WWT, with major funding from the EU LIFE Nature Programme, the HSBC 150th Anniversary Fund, Natural England, the National Lottery Heritage Fund through the Back from the Brink Programme, Leica and the Montague-Panton Animal Welfare Trust.

The maps below show the two breeding sites (Ouse and Nene Washes) and all the late-summer passage sites where head-started birds have been seen in England (left), and the international sightings of all godwits ringed in these breeding sites.

International Wader Study Group (IWSG)

The International Wader Study Group brings together everyone who has a passion for waders (shorebirds), the habitats they use and their conservation. Members include research scientists, citizen scientists and conservation practitioners from all around the world. IWSG gives out small grants each year that help to support wader projects around the world. Recent grants have been used to discover the wintering areas of Common Sandpipers, to measure the site-faithfulness of Dotterel and to support projects in Azerbaijan, Albania, Bangladesh & Argentina.

Mark and Jen

Jen Smart has worked for the RSPB for 14 years. As a scientist, she led RSPB’s research into the conservation problems faced by breeding waders and developed solutions to help these species. See the WaderTales blog Tool-kit for wader conservation. She developed the science programme around Project Godwit and maintains a keen interest in the project. Jen is Chair of the International Wader Study Group.

*‘Manea’ arrived at Old Hall Marshes (Kent) with his sister, ‘Lady’, in July 2017*

Mark has worked for the RSPB for 26 years and is Senior Site Manager at Berney Marshes, a 600 ha grassland nature reserve with around 300 pairs of breeding waders. See the WaderTales blog Managing water for waders. As well as managing the reserve, Mark works with other land managers across the country to develop and implement ways of improving habitats for breeding waders.

Latest news from Project Godwit

Project Godwit has been trialling the use of head-starting (https://projectgodwit.org.uk/), where young godwits are reared in captivity, safe from predators and potential flooding, and released once fledged. The aim is to boost the number of godwits breeding in England. The cycle route for Mark and Jen links eleven nature reserves in England, managed by a range of conservation organisations, where head-started Black-tailed Godwits have been spotted on migration by local birdwatchers.

*Nelson is one of the birds carrying a geolocator but he has not been recaught (yet)*

The ride started at WWT Steart Marshes in Somerset; visited by a Black-tailed Godwit named ‘Nelson’ in 2017. Birdwatchers throughout England were put on alert when the first head-started Black-tailed Godwits were released in 2017 but it was a surprise when Nelson headed southwest. Nelson is a star of Project Godwit. He returned to the Ouse Washes in 2018 and paired up with another head-started bird called ‘Lady’. They have met up in each subsequent spring. In February, Nelson spends time on the Tagus Estuary in Portugal but we don’t know whether he is one of the limosa Black-tailed Godwits that winters south of the Sahara.

The map below shows the route taken by Mark and Jen. The original plan was to cycle from Norfolk to the IWSG conference in Germany, which neatly linked the two causes for which they are seeking sponsorship – Project Godwit and the IWSG fund to support wader research. When the conference was rescheduled as an on-line meeting, they decided to join up the godwit dots across England. The 600-mile bike took just over a week.

*Jen & Mark’s route links RSPB, WWT, Wildlife Trustand county wildlife sites between Somerset and Cambridgeshire.*

The last site to be visited was the Nene Washes where, as mentioned above, the Black-tailed Godwit ‘Cornelia’ returned to breed. Having been raised at Welney, she was released at the Nene Washes on 27 June, 2018, wearing a small geolocator attached to a flag on her lime ring (see earlier picture). She is the only bird for which the RSPB and WWT team have a whole-year migration history. Cornelia was caught on a nest at the Nene Washes in 2019 and her geolocator was removed. In his blog on the Back from the Brink website, Mo Verhoeven shares his excitement when he learned that this young bird had flown directly from the Nene Washes to wetlands in Mauritania in just two days. There is more about Cornelia here.

Conservation challenges

Wetlands are under threat across the globe and it is appropriate that Mark and Jen are raising money for the International Wader Study Group and for Project Godwit. As they tweeted about their travels and talked about Black-tailed Godwits at local press events, at different nature reserves, they revealed some of the conservation challenges that waders face.

*The RSPB nature reserve at Titchwell (North Norfolk) is a favourite pit-stop for Project Godwit birds. These three youngsters, all head-started in 2018, visited before flying south.*

Project Godwit is not just about head-starting more Black-tailed Godwit chicks. The team is trying to improve the chances for nesting birds out on the Washes, using electric fences and other predation reduction schemes, and through the development of alternative breeding areas that are under less threat of flooding during spring and summer deluges.

Within Britain and when they head south through Europe and into Africa, Black-tailed Godwits are dependent upon a network of sites. Some of them are fully-protected nature reserves, others have been given international recognition as SPAs and Ramsar sites, but there are many other locations that are important but not designated. Sightings of Project Godwit birds and locations downloaded from geolocators will help to identify areas in which birds may be vulnerable to habitat change and new developments.

A new airport that is planned for the Tagus Estuary is a huge threat to limosa Black-tailed Godwits that breed in Western Europe, including the small English population. It’s thought that about half of the Project Godwit birds use the rice fields and mudflats of the Tagus Estuary, as you can read in Black-tailed Godwits are on their way home. As mentioned above, Nelson has been seen in the Tagus Estuary on several occasions (see map alongside). The proposed airport threatens many species of migrant waterbirds (Tagus Estuary: for birds or planes).

An important unknown when trying to conserve our larger wader species is ‘what happens to the teenagers?’. When do species such as Black-tailed Godwits start to breed and what do they do in the period between fledging and breeding? A key part of Project Godwit is to mark chicks in the wild, as well as head-started birds, hopefully answering questions such as ‘what proportion breed in their first year?’ and ‘where do immature birds spend the pre-breeding years’? Perhaps the International wader Study Group will be able to support similar work for other large shorebird species, through its small project grants?

Support for Mark and Jen

This epic sponsored cycle ride is funding work by Project Godwit and the IWSG. It was a great opportunity to thank colour-ring readers who have reported marked birds, to emphasise the importance of protecting networks of sites for migrant waders, and to highlight some of the conservation challenges that lie ahead.

If you would like to help Mark and Jen to support International Wader Study Group Small Projects Grants, please donate here: https://www.waderstudygroup.org/donate/

If you would like to help Mark and Jen to support the RSPB’s contribution to Project Godwit please donate here: https://www.justgiving.com/fundraising/fundsforwaders

Where to nest?

March 17, 2020March 25, 2020 / Graham Appleton / 5 Comments

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.

pic hidden Redshank

Iceland: a wader factory

table 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.

pic pretty graph

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.

pic fox attack

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

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

pic sheep

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

@grahamfappleton

Black-tailed Godwits are on their way home

March 4, 2020June 6, 2020 / Graham Appleton / 6 Comments

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

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

bg vero

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

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

Birds v Planes

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

Last chance for England’s breeding Black-tailed Godwits

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

Sep2019

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

Special Black-tailed Godwits
Site-fidelity in Black-tailed Godwits
Head-starting success

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

bg map

Migration

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

Birds on the Tagus in 2020

Black-tailed Godwits feeding in a Tagus rice-field

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

Class of 2017

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

bg remi in cage

Class of 2018

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

Class of 2019

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

Wild chicks 2017-2019

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

Earlier chicks

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

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

Ringed as adults

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

There are two colour-ringed birds in this photograph

One that won’t be seen again

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

Conservation importance of the Tagus Estuary

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

bg Hotting

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

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

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