Cycling for waders

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

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

Scotland’s Dotterel: still hanging on

Dotterel brooding chicks

Within the UK, the Dotterel now only breeds on plateaux in the highest Scottish mountains, restricted by habitat that is more commonly found in the arctic or arctic-alpine regions. 

As soon as climate change became apparent, the Dotterel turned into a focal species for ornithologists who were interested in how species would be affected by climate heating. Their fate seemed to be sealed; put simply, there is nowhere colder in Britain to which to retreat when faced with changing habitats and/or breeding conditions.

A 2020 paper by Steven Ewing, Alistair Baxter and colleagues explores the potential ways that changing environmental conditions may be driving the Dotterel’s decline.

Life history

Scottish Dotterels don’t actually spend much time in Scotland, with most birds arriving in early May and leaving within three months. The large part of the year is spent in North Africa, and the plains to the northwest of the Atlas Mountains in Morocco seem to be a particularly important wintering grounds for Scottish birds. Migration north and south appears to be direct, with few European reports of ringed birds in spring and autumn. There is some evidence that Dotterel move further south within North Africa as winter progresses (Whitfield et al 1996), perhaps responding to rainfall patterns.

In May, the numbers of males and females on Scottish breeding sites are roughly equal but many females leave their males sitting on a first clutch of eggs and then depart, leading to an observed drop in sex ratios to about 10:1. Females ringed in Scotland have been spotted breeding with Norwegian males later in the same season and this onward movement to areas with later snow-melt may well be a normal pattern. Indeed, many Dotterels seen on passage in May, often on traditionally used fields or mountain tops south of the Scottish Highlands, may loop north, passing through Highland nesting haunts and then heading northeast into Scandinavia.

A species in decline

Alistair Baxter points to a Dotterel nest that’s right next to a path following the line of a ridge

Dotterels in Britain are at the south-western limit of the species’ global range. They breed almost exclusively in arctic-alpine habitats above 750 m, particularly on Racomitrium moss-heaths that are so characteristic of the flatter topped mountains. These habitats are of high conservation concern, with a tapestry of nationally-rare alpine and arctic plant species.

Scottish Dotterel have been well-studied for over eighty years, a process that was started by Desmond Nethersole-Thompson in the 1940s (detailed in his classic monograph The Dotterel, 1973) and has involved the authors of the Global Change Biology paper since 1987. Some of the areas featured in this paper were studied by Nethersole-Thompson.

An earlier WaderTales blog (Dotterel numbers have fallen by 57%) suggested a number of possible reasons for declines – habitat changes, increased predation and increased disturbance in the Scottish Highlands, compounded by issues affecting the wintering population in North Africa. In the 2020 paper, Ewing et al look in more detail at the potential roles of these changes

Climate and habitat change in Scotland’s mountains

Mountains in Britain are subject to a range of environmental drivers of change that may potentially influence Dotterels, but the logistical challenges presented by working in these environments means that there is rarely good data documenting these changes. This study focuses on snow cover and nitrogen deposition.

The amount of snow-cover is important for cold-adapted species of plants and animals; it insulates the ground in winter and slows up warming in spring, thereby creating a relatively stable environment.  Potential consequences of changes in winter snow-lie for alpine birds might include:

• A longer growing season for plants, with taller vegetation that reduces the suitability of these areas for species that favour shorter swards.
• Fewer snow patches, around which Dotterel feed, perhaps also leading to a reduction in peak insect abundance that may not match feeding requirements of chicks.

Lots of research carried out in the UK shows that nitrogen deposition is an important driver of upland vegetation change.  Higher deposition of nitrogen tends to result in a reduction of alpine specialist plants, including species of mosses that form key breeding habitats for Dotterel.

The earlier WaderTales blog (Dotterel numbers have fallen by 57%) suggested other possible reasons for Dotterel declines on the breeding grounds, including increased predation and increased disturbance in the Scottish Highlands. While these potential drivers of change could not be tested, due to a lack of data, they are considered in the paper’s Discussion.

Study system

The data that lie at the heart of the Global Change Biology paper have been collected over three decades. Two different but complementary data sources were used in the study.  Firstly, Dotterel were counted at between 128 and 198 alpine sites in the UK during three national surveys in 1987-88, 1999 and 2011.  These censuses focused upon suitable breeding habitats, especially Racomitrium heath, with the latter two surveys successfully covering more than 50% of identified breeding areas.  Secondly, between 1987 and 1999, a smaller cohort of alpine sites were surveyed with far greater frequency (between 40-60 times) as part of SNH’s Montane Ecology Project, where the aim was to study the Dotterel’s breeding ecology in far more detail. The 2020 paper contains detailed information about site use and the parameters that were measured/assessed (elevation, slope, area, snow cover, nitrogen deposition, summer temperature etc.)

Each site visit involved a lot of climbing, so many of the sites were visited only once per season, with more frequent visits to just 15% of the sites. Having accompanied Phil Whitfield (one of the authors) up one mountain, on one day, I have huge respect for the effort that each data-point represents.  Once up on the tops, observers covered the study areas thoroughly, passing within 100 m of every point and scanning frequently. This has been shown to provide a good count of breeding males.

The authors used their data to investigate whether key potential drivers of environmental change in Scottish mountains (snow-lie, elevated summer temperatures and nitrogen deposition) may have contributed to the population decline of Dotterel.  They also consider the role of rainfall on the species’ wintering grounds in North Africa. The key questions they address are:

1. Is there evidence of an uphill shift in the elevation of the Dotterel’s breeding range during the study period (1987-2014)?
2. Are changes in the density or site occupancy of breeding male Dotterels associated with the size, connectedness or topographical aspect of alpine sites?
3. Does spatial variation in atmospheric nitrogen deposition account for variation in density or occupancy of breeding males at alpine sites?
4. Are patterns of snow cover or late summer temperatures associated with density or occupancy of male Dotterels at alpine breeding sites?
5. Do densities of breeding male Dotterels on alpine sites vary with conditions on the North African wintering grounds, as reflected by winter rainfall?

What has changed?

The results are presented in two ways. Data from the period of intensive studies, between 1987 and 1999, are used to try to understand factors influencing annual changes in the number of nesting males. Examination of changes between 1987-90 and 2011-14 gave some indication of factors affecting longer-term trends – something that is important to understand when Dotterel can live for at least ten years.

Densities of breeding male Dotterel in mountainous regions of Scotland declined between 1987 and 1999 and, over the longer-term, site occupancy fell from 80% in 1987 to only 36% in 2014. Densities of breeding males declined disproportionately from lower-lying sites, which resulted in the Dotterel’s breeding range retreating uphill at a rate of 25 m per decade.

Geographically isolated sites appear more likely to lose breeding Dotterel. This makes sense; playback studies in Russia have shown that passing flocks of Dotterel respond to calls, suggesting that birds will be attracted to already-occupied locations.

Settlement patterns were linked to snow-cover.  Generally, Dotterels appear to prefer to settle on higher sites, but late-lying snow at higher elevations appears to deprive them of suitable breeding habitat.  Rather than delay nesting, it seems that these birds then choose to move to lower snow-free sites to breed. Long-term changes in snow cover are poorly documented in high-elevation habitats in Scotland, so it is difficult to know whether the substantial declines observed for Dotterel in recent decades reflect systematic changes in snow-lie.

Nitrogen deposition was shown to be negatively associated with densities of males nesting at lower and intermediate elevations.  The primary impact of nitrogen deposition on Dotterel is likely to be via effects on the species’ favoured Racomitrium moss-heaths, with greater nitrogen levels increasing the rate of moss decomposition and favouring accelerated grass growth.  This presumably results in these habitats becoming increasingly unsuitable for breeding Dotterel.

Will this chick makes it to Morocco? If it does, how will the conditions it experiences in the non-breeding season affect its probability of return to Scotland?

High rainfall in North Africa seems to lead to higher densities of breeding male Dotterel two springs later, suggesting that wintering ground conditions can potentially influence population dynamics of this alpine-breeding bird.  Similar positive impacts of North African rainfall have also been seen in Ring Ouzels that breed in the UK (Beale et al. 2006).

Dotterel inhabit open farmland and sub-desert steppes in North Africa, where seasonal rainfall brings a flush of vegetation growth and insect abundance. Higher winter rainfall may increase prey availability and Dotterel survival rates but that would be reflected in the arrival numbers in the next spring. The lag of an extra year suggests that low rainfall levels may mostly affect young birds, perhaps delaying recruitment of some Dotterels until their second breeding season.

Conclusions

Population declines and site abandonment by Dotterel in Scotland during the last three decades have largely occurred at lower elevations, fitting with the traditional idea of climate change limiting the available climate space for alpine breeding species. However, this study found relatively limited evidence that the decline in the breeding population is being driven by climatic factors on the breeding grounds.

Snow cover does seem to influence year-to-year variation in the species’ elevational distribution in Scotland, potentially because a smaller population may now be increasingly settling on higher sites that perhaps were previously unavailable, due to extensive snow cover.  There was also some evidence that greater nitrogen deposition reduced breeding densities of Dotterel at low to intermediate elevations, perhaps by decreasing the suitability of Racomitrium moss heath breeding habitats.  It is also possible that there may have been a redistribution of birds, with newer generations moving further north, to more suitable sites in Norway. (There is a WaderTales blog about this sort of Generational Change mechanism in waders, focusing on Black-tailed Godwit).

Given that Dotterels spend so little time in Scotland, a big gap in our understanding is what is happening in Morocco, where adult Scottish Dotterel spend three-quarters of the year and where young birds may also spend their first summer. How are factors such as rainfall and land-use (particularly farming methods) affecting Dotterels? Might changes in these areas affect other species of migrant that leave northern Europe at the end of the breeding season? Perhaps conservation scientists need to head south for the winter to find out?

Read more in the paper

Clinging on to alpine life: investigating factors driving the uphill range contraction and population decline of a mountain breeding bird. Steven R. Ewing, Alistair Baxter, Jeremy D. Wilson, Daniel B. Hayhow, James Gordon, Des B. A. Thompson, D. Philip Whitfield & René Van der Wal. Global Change Biology.

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WaderTales blogs are written by Graham Appleton, 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.

@GrahamFAppleton

 

WaderTales blogs in 2019

Nineteen new WaderTales blogs were published during 2019. Click on a link in bold to read an individual blog.

Ringed Plovers often have time to nest again if the first clutch is lost

Over 25,000 people, representing 130 countries, visited the WaderTales website during 2019.

• The most widely-read blog was Ireland’s Curlew Crisis, reflecting the international concern for the species and the culew family as a whole.
• It is great that the next most popular blog is Managing water for waders, as this is such a positive story about how farmers, conservation organisations and statutory agencies can work together to deliver better habitat for breeding waders and an improved water supply for farmers.
• In third place is Sixty years of Wash waders which describes six decades of scientific outputs of the Wash Wader Ringing Group. The WWRG’s founder, Clive Minton, died in tragic circumstances just a couple of months later and there are some lovely tributes here, on the International Wader Study Group website.

Migration

The distinctive white under-wing of a Steppe Whimbrel

The migration blogs cover a wide range of species:

• Generational Change uses colour-ring sightings to explore how Black-tailed Godwit populations have changed in distribution and migratory timing.
• Whimbrel: time to leave summarises a paper about the consistencies and variability of annual migration patterns of individual Whimbrel.
• Red Knot pay the price for being fussy eaters discusses the reliance of Delaware Bay birds on the unpredictable annual supply of horseshoe crab eggs. Why are Ruddy Turnstones better able to cope in a changing world?
• Not-so-Common Sandpipers mixes information about migration with a review of Common & Spotted Sandpipers by Phil Holland.
• Travel advice for Sanderling summarises research to understand the pros & cons of spending the non-breeding season in widely different locations. Birds in equatorial Africa do far less well than those in England and Namibia.
• In search of Steppe Whimbrel summarises a paper about two very special individual Whimbrel. Will this knowledge help to rescue a subspecies?

Breeding waders

Redshanks need long grass in which to hide their nests

There is bad news for Curlew and Redshank, some interesting information about the effects of ticks on chicks and an important stock-take of Fennoscandia’s breeding waders.

• Redshank – the ‘warden of the marsh’ focuses on Redshank that breed on saltmarshes and the agricultural subsidies that help to fund their conservation.
• From local warming to range expansion explores the role of climate warming in fuelling the century-long range expansion of Iceland’s Black-tailed Godwit population.
• Ireland’s Curlew Crisis focuses on the nationwide breeding survey between 2015 and 2017, which revealed a 96% decline in the number of pairs in the previous 30 years.
• Chicks and Ticks reviews a study of the effects of ticks on the survival probability of Golden Plover chicks.
• Fennoscandian wader factory summarises analyses of breeding wader numbers in Finland, Sweden and Norway over the period 2006 to 2018.
• Managing water for waders celebrates work to reduce flooding, store fresh water for farmers and create habitat for breeding waders.
• Time to nest again? asks how much of the advantage of being an early migrant could be associated with having an option to nest again, if the first attempt fails.

Winter waders 

Winter numbers of Oystercatcher and Knot have declined in Britain and Ireland

The Green Sandpiper blog reveals unpublished information about territoriality. The other two blogs in this section summarise population estimates of waders in Great Britain and Ireland, based on new papers in British Birds and Irish Birds.

• Winter territories of Green Sandpipers includes unpublished information from southern England, where survival is affected by the severity of winters.
• Do population estimates matter? is inspired by the waders section of Population estimates of wintering waterbirds in Great Britain, based on data from the Wetland Bird Survey and the Non-estuarine Waterbirds Survey.
• Ireland’s wintering waders complements the above blog, providing information from I-WeBS and WeBS for the island of Ireland and set in a European context.

The others!

Adding colour rings and individual flags to Grey Plover

One of the aims of these blogs is to engage people in projects that are in need of volunteers or other forms of public engagement – hence the Northern Ireland blog. The other two articles celebrate sixty years of The Wash Wader Ringing Group and share concerns about a new airport for Lisbon, to be built right next to the Tagus/Tejo Estuary.

• The Waders of Northern Ireland was written as a promotional tool for a 2019 breeding survey but covers wintering and passage species too.
• Sixty years of Wash waders celebrates the longest-running wader-ringing project in the UK  (and the world?), by summarising six decades of migration research.
• Tagus estuary: for birds or planes? What could go wrong if an international airport is built right next to an estuary that is important to Black-tailed Godwits?

Vast flocks of Black-tailed Godwit gather in the Tagus Estuary in February

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.The intention is to add one or two new blogs each month. You can sign up to receive an e-mail notification when a new one is published. Full list of blogs here.

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

January to June 2019

One or two WaderTales blogs are published each month. The series is UK-based with a global reach. Suggestions of newly-published research on waders that might be of interest to birdwatchers who appreciate waders/shorebirds are welcomed. I am particularly keen to give feedback to colour-ring readers; they provide a huge amount of information that lies at the heart of these stories.

Click on a link in bold to read an individual blog.

• Winter territories of Green Sandpipers includes unpublished information from southern England, where survival is affected by the severity of winters.
• In search of Steppe Whimbrel summarises a paper about two very special individual Whimbrel. Will this knowledge help to rescue a subspecies?
• From local warming to range expansion explores the role of climate warming in fuelling the century-long range expansion of Iceland’s Black-tailed Godwit/
• Ireland’s Curlew Crisis focuses on the nationwide breeding survey between 2015 and 2017, which revealed a 96% decline in the number of pairs in just 30 years.
• Do population estimates matter? is inspired by the waders section of Population estimates of wintering waterbirds in Great Britain, based on data from the Wetland Bird Survey and the Non-estuarine Waterbirds Survey.
• The Waders of Northern Ireland was written as a promotional tool for a 2019 breeding survey but covers wintering and passage species too.
• Ireland’s wintering waders provides the latest population estimates of waders wintering in Ireland, set within in a European context.
• Redshank – the ‘warden of the marsh’ focuses on Redshank that breed on saltmarshes and the agricultural subsidies that help to fund their conservation.
• Not-so-Common Sandpipers mixes information about migration with a review of Common & Spotted Sandpipers by Phil Holland.
• Chicks and Ticks reviews a study of the effects of ticks on the survival probability of Golden Plover chicks.
• Managing water for waders celebrates work to reduce flooding, store fresh water for farmers and create habitat for breeding waders.

You can sign up to receive an e-mail notification when a new blog is published.

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

Are there costs to wearing a geolocator?

If you’re thinking of using geolocators to study bird migration then here’s a paper that you should read.

Whimbrels on the move (Tómas Gunnarsson)

Devices attached to waders (shorebirds) are adding hugely to our understanding of their movements, and informing plans for the conservation of threatened species, but how safe are these devices for the individual birds that carry them? Emily Weiser and 49 coauthors have reviewed the available evidence in their paper Effects of geolocators on hatching success, return rates, breeding movements, and change in body mass in 16 species of Arctic-breeding shorebirds, published in Movement Ecology.

Whimbrel wearing a geolocator (Camilo Carneiro)

Marking birds is not without cost. Catching a bird to fit a ring, however light and however expertly applied, subjects the individual to extra risk. Perhaps the ring might get wool tangled around it for instance? Logic suggests that every extra device, from colour-rings through to a harness that carries a satellite tag, adds mass and potential problems. This paper focuses on geolocators – the half-way house between satellite tags and colour-rings, in terms of weight. I find it encouraging that so many scientists have combined in this review of the way that geolocators affect birds’ lives. By providing their data for analysis, they remind us that professional ornithologists have a shared concern for the birds that they work on. As people, they want to minimise the effects on individual birds and, as scientists, they need to reassure themselves that tagged individuals are providing data that are representative of other birds of the same species.

What are geolocators?

This Semipalmated Sandpiper carried a geolocator for two years (Emily Weiser)

Geolocators collect information on place and time. Unlike satellite tags, which can relay information from the bird to the scientist on a day-to-day basis, geolocators have to be deployed and then retrieved, so that data can be down-loaded. In the intervening period, these tiny devices record the time of dawn and dusk, information that can be decoded to reveal daily locations, apart from during the periods of spring and autumn equinoxes (when day length is virtually independent of latitude) and if there is heavy cloud.  Geolocators are particularly useful for waders, as most of them live in very open environments (but less good for nocturnal species such as woodcock).

The data used in this paper relate to geolocators weighing between 0.8g and 2.0g, representing 0.1– 3.9 % of mean body mass of the species to which they were applied. They were attached to 16 species of migratory shorebirds, including five species with between 2 and 4 subspecies, making a total of 23 study taxa. The smallest species was only 26 grammes and the largest was just over a kilogramme. Birds were tagged at 23 breeding and eight nonbreeding sites, spread throughout the world.

Geolocators can be attached to harnesses and sit on the back of birds or, as in most cases studied here, attached to a ring or flag on a bird’s leg. The paper looks at the different effects of tags mounted in different ways.

Invaluable Data

Many wader populations are in trouble. Of the eight curlew species, for instance, one or two species are probably extinct, three others are endangered, vulnerable and near-threatened and only three are not causing concern. 

Establishing migratory routes and the timing of movements is a critical part of understanding the migration strategies of waders. The results collected from geolocators have important consequences for conservation and are truly fascinating. Who would have believed that Red-necked Phalaropes breeding in Shetland (north of Scotland and west of Norway) would migrate west and south to spend the winter on the surface of the Pacific Ocean between Galapagos and Ecuador? Geolocator tagging reveals Pacific migration of Red-necked Phalarope Phalaropus lobatus breeding in Scotland. Smith, M., Bolton, M., Okill, D.J., Summers, R.W., Ellis, P., Liechti, F. & Wilson, J.D. Ibis. DOI: 10.1111/ibi.12196

Waders operate at a truly global scale, with Bar-tailed Godwits making phenomenal journeys directly from Alaska to New Zealand. This species and others using the East Asian-Australasian flyway are causing major concerns for wader biologists, who have measured huge losses in populations wintering in Australia, New Zealand and south-east Asia. Ringing and colour-ringing had shown that birds fly north each spring to eastern Siberia and Alaska via the coast of eastern Asia – countries such as South Korea and China where there are major development pressures upon estuaries. Simultaneous declines in summer survival of three shorebird species signals a flyway at risk. Theunis Piersma,Tamar Lok, Ying Chen, Chris J Hassell, Hong-Yan Yang, Adrian Boyle, Matt Slaymaker, Ying-Chi Chan, David S Melville, Zheng-Wang Zhang, Zhijun Ma. Journal of Applied Ecology. DOI: 10.1111/1365-2664.12582

Identifying key staging sites, such as the northern end of the Sakhalin peninsular, was possible thanks to the deployment of geolocators, as shown in this paper. Movement patterns of Sanderling (Calidris alba) in the East Asian–Australasian Flyway and a comparison of methods for identification of crucial areas for conservation. Simeon Lisovski, Ken Gosbell, Maureen Christie, Bethany J. Hoye, Marcel Klaassen, Iain D. Stewart, Alice J. Taysom and Clive Minton. Emu. DOI 10.1071/MU15042

East Asian-Australasian Flyway Partnership

Using this information, conservation organisation and governments have started to work together to campaign for more sympathetic development of key areas. Conservation without borders – solutions to declines of migratory shorebirds in the East Asian–Australasian Flyway. Judit K. Szabo, Chi-Yeung Choi, Robert S. Clemens and Birgita Hansen. Emu. DOI 10.1071/MU15133

This is just one of many examples of the use of geolocators to fill gaps in migratory stories for waders. Geolocators are also being used to establish wintering areas for breeding species (e.g. Knot in South America) and to assess remotely whether individuals nest successfully. Using Geolocator data  to reveal incubation periods and breeding biology in Red Knots Calidris canutus rufa. Burger J, Niles L J, Porter R R & A D Dey. Wader Study. 119(1): 26–36.

Conclusions

It is not possible to reproduce all of the results in the paper here, or to list all the caveats presented by the authors, but these are the salient points. Anyone considering using geolocators on waders/shorebirds will want to read the whole paper in detail.

• Importantly, no negative effects of geolocators were detected for most species of shorebirds – including some that migrate huge distances.
• For some small-bodied taxa (mean body mass ≤58 g), there were substantial negative effects. Geolocators reduced nest success, hatching rate, and/or return rate for two small-bodied species – Semipalmated Sandpipers and Arcticola Dunlin.
• Changing the way that a geolocator is mounted on the leg can have consequences in terms of return rates and damage to eggs. Simple changes, such as rounding the corners of flags may reduce problems.
• Studies of the same species in different areas produced different results, in terms of the impacts of geolocators.
• The findings suggest that guidelines for the relative mass of devices, as developed for backpack-style attachments, may be too liberal for leg-mounted tags. The graph presented in the paper suggests that negative effects may be detected when the tag and attachment together weigh more than 1.5% of body mass.
• It is not unusual for a wader to live for more than ten years; the studies that contribute to this paper are mostly of short duration and cannot assess long-term effects of tags.

Tómas Gunnarsson

To learn more please read the paper: The effects of geolocators on hatching success, return rates, breeding movements, and change in body mass in 16 species of Arctic-breeding shorebirds. Emily L. Weiser, Richard B. Lanctot, Stephen C. Brown, José A. Alves, Phil F. Battley, Rebecca Bentzen, Joël Bêty, Mary Anne Bishop, Megan Boldenow, Loïc Bollache, Bruce Casler, Maureen Christie, Jonathan T. Coleman, Jesse R. Conklin, Willow B. English, H. River Gates, Olivier Gilg, Marie-Andrée Giroux, Ken Gosbell, Chris Hassell, Jim Helmericks, Andrew Johnson, Borgný Katrínardóttir, Kari Koivula, Eunbi Kwon, Jean-Francois Lamarre, Johannes Lang, David B. Lank, Nicolas Lecomte, Joe Liebezeit, Vanessa Loverti, Laura McKinnon, Clive Minton, David Mizrahi, Erica Nol, Veli-Matti Pakanen, Johanna Perz, Ron Porter, Jennie Rausch, Jeroen Reneerkens, Nelli Rönkä, Sarah Saalfeld, Nathan Senner, Benoît Sittler, Paul A. Smith, Kristine Sowl, Audrey Taylor, David H. Ward, Stephen Yezerinac and Brett K. Sandercock. Movement Ecology 20164:12. DOI: 10.1186/s40462-016-0077-6

Implications

I am sure that members of panels charged with the task of issuing permits to those engaged in migration research will find this study tremendously useful, especially as so much detail has been made freely available within the paper and in supplementary material. It is hugely encouraging that, for most species, there is no evidence that the costs to individuals outweigh the potential conservation benefits. Future decisions to deploy devices on small-bodied shorebirds will be made on a case-by-case basis, weighing the potential impacts on individuals and populations against the value of improved knowledge of migratory movements.

Additional information

This later WaderTales blog, about Green Sandpipers, considers behavioural responses associated with wearing geolocators attached using a harness: Green Sandpipers and Geolocators.

 

 

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

@grahamfappleton

Whimbrels on the move

You may hear the distinctive seven-note call of a Whimbrel overhead in late April or May but where is it going and where has it been?

Many pairs of Whimbrel nest in the flood-plains of Iceland’s rivers (Tómas Gunnarsson)

In a 2016 paper in Wader Study, Tómas Gunnarsson and Guðmundur Guðmundsson analysed the ringing recoveries of Icelandic Whimbrel and demonstrated that many probably make non-stop flights from Iceland to western Africa.  The study also helped to explain the timing and origins of flocks of Whimbrel in different parts of the British Isles in spring and late summer.

Migration and non-breeding distribution of Icelandic Whimbrels Numenius phaeopus islandicus as revealed by ringing recoveries: Tómas Grétar Gunnarsson and Guðmundur A. Guðmundsson (Wader Study). The paper is available here.

Since the publication of this paper, further details has been added using geolocators, small tags that collect information on the movements of birds over a twelve-month period, and now using satellite tracking. There’s more about this work at the end of this blog.

Whimbrels in Iceland

It is estimated that 250,000 pairs of Whimbrel  breed in in Iceland, representing 25% of the combined global population for all seven subspecies of Whimbrel and making Iceland a very important country for the species. The Icelandic breeding population is believed to be relatively stable but others, such as those in North America, are in decline.

There are two blogs about how volcanic dust affects Whimbrel. In the long-term volcanic ash provides important fertilizers but short term effects can be seen in breeding success.

The Whimbrel is one of the commonest of Iceland’s breeding wader species, with most nests estimated to be at elevations lower than 200m and particularly along river flood-plains.

Iceland is a country in a state of constant flux, both because of geothermal activity and the subsequent physical processes associated with wind and water flow, and as a result of human interventions. Volcanic ash has been shown to affect the breeding success of Whimbrels in the short term and their distribution in the longer term. Land use is also changing rapidly, particularly as a result of afforestation and the ways that land is farmed, and work is ongoing to understand how these processes might impact upon breeding waders, including Whimbrels.

Movements of Icelandic Whimbrel

Nesting Whimbrel hunkers down in heathland vegetation – a very different habitat to the mud and mangroves of West Africa (Tómas Gunnarsson)

Over 6000 Whimbrels have been ringed in Iceland since 1921, with 95% of these caught as chicks. 35 Icelandic-ringed Whimbrels have been recovered abroad and 4 foreign-ringed Whimbrels have been found in Iceland.  In their paper, Tómas and Guðmundur show that most of the winter records of Icelandic birds are in west Africa, between Mauritania in the north and Benin and Togo in the south, but that there are two January records in Spain, suggesting that some individuals don’t travel further south than Europe.  Spain and Portugal cannot be particularly important wintering areas for the species, however, as Whimbrel counts across Spain and Portugal don’t exceed 1000 birds, which represents a tiny part of the Icelandic population, even if they are all assumed to originate from there.

Reproduced from Gunnarsson & Gudmundsson 2016 with permission from Wader Study

Spring and autumn Whimbrel records that link Iceland with Britain and Ireland show strikingly different distributions for the two seasons.  There are eight recoveries in the British Isles on spring passage; 1 in Ireland and 7 in western counties of the UK. There is only one autumn passage record (in the Outer Hebrides), despite the fact that autumn shooting of Curlew, which did not stop until 1981, might have been expected to have produced recoveries of similar Whimbrel. This strongly suggests that, while some whimbrel stop off on northwards migration, the southerly journey is straight to Africa. We know that this is possible, because a satellite-tagged Whimbrel was tracked making a direct flight from Iceland to Guinea-Bissau in late summer 2007.

Counts and recoveries of British birds

Some of the big WeBS counts for Whimbrel are made in the late summer, with over 1500 birds reported on the Wash (August), nearly 300 along the North Norfolk coast (August) and nearly 200 in July in each of Chichester Harbour (Hampshire) and Morecambe Bay.  Largest counts in spring are mainly in the west and all in April, with 331 on the Severn, 339 on the Ribble and 654 in the Fylde area but one east coast site (Breydon Water in Norfolk) has had a spring count of 137. Although April & May flocks might seem large, they should be viewed in context – at least 500,000 Whimbrel travel back to Iceland each year.

The only British-ringed Whimbrels to have been found in Iceland have been two satellite-tagged birds, one of which is mentioned above, but metal-ringed birds have returned to breeding grounds in Finland, Russia and Sweden. Given that this new paper suggests no links between eastern Britain and Iceland in the autumn, it is likely that the large number of birds that spend the moult period on east coast estuaries such as the Wash are mainly of continental origin. The same is probably true for late-summer gatherings, such as the ones in Chichester Harbourand Morecambe Bay.

Tómas Gunnarsson

In order to understand more about spring flocks of Whimbrel in the UK, ringing and satellite tagging has been taking place in the Lower Derwent Valley (East Yorkshire). Birds tagged here have flown to both Iceland and Sweden which indicates that Icelandic and continental birds gather together in April and May flocks. Despite this mix of subspecies in Yorkshire, the lack of ringing recoveries of Icelandic birds in the east of the UK suggests that continental birds make up the majority of spring flocks in the east.

To summarise: if you hear a Whimbrel calling overhead in the autumn it is probably of continental origin, especially in the east. On spring passage, a seven-note call in the west may well have an Icelandic twang but in the east it could sound that little bit more Scandinavian. If only we could tell them apart.

To learn more about the migration of over 40 wader species to, from and through Britain & Ireland, check out this WaderTales blog.

Update: Tracking helps to provide more insights

Tómas Gunnarsson

This analysis of metal-ringed birds set the context for new studies to understand the migration strategies of individual Icelandic birds, using geolocators and satellite tags.

The first paper using these data appeared in Nature’s Scientific Reports. In it, José Alves and his colleagues show that four birds completed the autumn migration in one flight. On return in spring, two of these birds stopped off in Ireland and two flew straight to Iceland.

Camilo Carneiro developed the work further, working with supervisors Tómas Gunnarsson and José Alves. By increasing the sample size of birds carrying geolocators from Iceland and back again, he was able to show that all of the adults in his sample were able to migrate directly from Iceland to West Africa at the end of the breeding season. Only 20% of journeys north in the spring were completed without refuelling. Most of these stops were in Ireland and western Britain, as predicted from the results of the ringing analyses summarised above. See Iceland to Africa non-stop.

By tracking birds in more than one year, Camilo has gone on to show that the fixed point in an Icelandic Whimbrel’s annual cycle is spring departure from Africa. See Whimbrel: time to leave.

With further research it should soon be possible to understand how these epic sea crossings from Iceland to Africa are affected by prevailing winds and varying weather patterns, whether individuals use the same strategies in different years and if a juvenile can make it all the way to Africa on its maiden flight.

Meanwhile, you can help with the studies of migration by looking out for and reporting colour-ringed Whimbrel. Most of the ones seen in Britain & Ireland will have been marked by researchers in Iceland and they will be delighted to hear news of their birds at icelandwader@gmail.com.

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

@grahamfappleton

Godwits in, Godwits out: springtime on the Washes

It’s all change in the East Anglian Washes in April, as a small number of limosa Black-tailed Godwits return to breed while thousands of islandica godwits are preparing to depart.

Black-tailed Godwits land in front of the main hide at WWT Welney (Graham Catley)

The Ouse and Nene Washes in Norfolk and Cambridgeshire are designated as Special Protection Areas (SPAs) under the European Birds Directive, in large part because of their breeding and wintering wader populations. Although the primary reason for their esixtence is to store water that falls as heavy rain further inland, and to thus prevent the flooding of  arable farmland, this periodic inundation has created areas that are relatively free of development and hence great nature sites.  There are no buildings and farming is largely restricted to seasonal grazing, much of which is tailored to provide appropriate feeding areas for wader chicks in the summer and ducks in the winter.

Limosa godwits

GW-WB was ringed as a chick on the Nene Washes in 2001 and turned up at Cley, on the Norfolk coast, in June/July of six summers between 2005 and 2013  (Pat Wileman)

Typically, only about 40 pairs of limosa Black-tailed Godwits attempt to breed on the Nene Washes each year and 2 to 4 pairs on the Ouse Washes.  Productivity can be low, despite positive habitat management, with summer flooding accounting for frequent losses on the Ouse Washes, while predation has become a recent issue affecting productivity on the Nene Washes.

Problems for breeding limosa are not restricted to England. This is a race that is in trouble, especially in the Netherlands, where the Black-tailed Godwit is the national bird. Attempts have been made to adapt grassland management during the breeding season and to restrict autumn hunting in France but numbers are still declining. There could also be problems with declining area and quality of wetlands in West Africa, where these birds spend the middle part of the winter.

Many chicks from the Nene Washes were colour-ringed by RSPB scientists between 1999 and 2003. We know that some of these birds turned up at coastal sites in England in the early autumn before joining birds from continental Europe as they travelled south through France, Spain and Portugal and on to countries such as Mauretania and Guinea Bissau in western Africa.

YR-RE feeding with a Dutch-ringed limosa in Senegal (Bram Piot)

A new colour-ring scheme started in 2015, which also involves marking breeding adults. It produced the first colour-ring observation of a Nene-breeding Black-tailed Godwit in Africa. YR-RE (Yellow Red – Red E-Lime) was spotted feeding near Dakar, Senegal on 3^rd and 4^th January 2016. She was seen again on a Portuguese rice-field on 2^nd February 2016. When she returns to the Nene Washes of Cambridgeshire she will find lots of islandica already in residence.

Limosa or Islandica?

The forehead is more prominent in islandica (Pat Wileman)

It is not easy to distinguish between the two races of Black-tailed Godwits, unless there are marked individuals wearing colour-rings. Even in breeding plumage the differences are subtle. Some male islandica are small and dark but there is much variation across the subspecies. Head shape may be helpful. In the pictures alongside, the bill of the limosa seems to be a smooth extension of the head and there is much less of a distinct forehead than in an islandica. Body size and shape measurements may assist researchers but birds can still be misidentified in the hand. Occasional birds that have been satellite-tagged as limosa in Portugal or Spain end up migrating to Iceland instead of the Netherlands.

Islandica godwits

G -GO/W was one of the Stour birds that visited Welney (Ed Keeble)

The Washes have not been managed for Icelandic Black-tailed Godwits and their use of the site in the winter is a relatively new phenomenon. These days a flock can appear at the WWT Welney Reserve as early as November and there will almost certainly be some birds to see on the reserve or on nearby washes, unless water levels are very high. Many of these godwits will have previously moulted close by, on the Wash & Humber, but others will join them from the Suffolk and Essex estuaries. When Jenny Gill and I visited the site on 30 December 2015 there had been a recent influx of birds and we identified 42 colour-ringed individuals from east coast estuaries. In January 2016, following heavy rainfall that flooded the Washes, there was a sudden influx of hundreds of extra godwits to the Stour estuary in Essex, that included several that we had seen at Welney in December.

As February turns to March and then April, more new birds join the flocks feeding along the water’s edge in the flooded washes. The appearance of birds wearing orange flags and green flags signals the arrival of individuals from France and Portugal. Although most birds that winter in continental Europe prepare for the last leg of their journeys to Iceland in The Netherlands others choose to fatten up in eastern England.

Use of the Nene Washes is less predictable than the Ouse Washes but large flocks can be found during late March and April. In some springs, four-figure flocks feed on the RSPB reserve at Welches Dam on the Ouse but in others, such as in 2016, the water levels are too high and birds appear on the Nene Washes at Eldernell and further west towards Peterborough on the Low Washes.

Conservation importance for islandica

Graham Catley

Every time a birdwatcher reports a flock of 1000 islandica Black-tailed Godwits, she or he is looking at around 2% of the whole Icelandic population, which now likely numbers around 60,000 birds. One of the largest single flocks that has been reported in the area was 4000 on the Nene Washes on 9 March 2008, which must have been about 15% of the Icelandic population at that time. This is an amazingly large part of any wader population to be seen in one place and emphasises the tremendous importance of the Nene and Ouse Washes. Fortunately, much of the land in these areas is farmed in such a way as to provide great breeding and wintering conditions for ground-nesting birds. The only problems occur when prolonged flooding means that these resources are not available to birds preparing for the flight to Iceland

New hope for limosa breeding in the Ouse & Nene Washes

Nene Washes RSPB reserve (RSPB)

These are exciting times for limosa godwits in the UK. The RSPB, in partnership with WWT, have attracted European funding for a five-year recovery project for these birds. Securing the future of the Nene-breeding godwits is central to this project, through increasing the area of suitable breeding habitat and improving predator management, alongside research to assess the success of these actions.

One of the key actions is to trial head-starting – taking a small number of early clutches of eggs and raising chicks in a predator-free environment. You can read more here. Project Godwit is a partnership between RSPB and WWT with major funding from the EU LIFE Nature Programme, HSBC, Natural England and the Heritage Lottery Fund.

Having only one really key breeding area always leaves a population vulnerable, so re-establishing more breeding populations on the newly created wet grasslands adjacent to the Ouse Washes is also critical to the future of Black-tailed Godwits, as a breeding species in the UK.

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

@grahamfappleton

 

Big Foot and the Redshank Nest

What’s the crunch point? Grazed saltmarsh is an important habitat for Redshank but the addition of an extra four large feet can have serious negative effects. 

Each grazing unit comes with four very large feet (Adam Cross)

In a 2016 paper in Agriculture, Ecosystems & Environment, Elwyn Sharps and colleagues from Bangor University, CEH and the RSPB have shown that there is a tricky balance between providing the open, grazed habitats in which Redshanks can breed and minimising the likelihood of nests being trampled by cattle. If only cattle could do their important habitat management work outside the nesting season? However, the grass keeps growing and these four-footed, saltmarsh mowing machines usually arrive on site in spring and stay throughout the summer.

Sharps, E., Garbutt, A., Hiddink, J. G., Smart, J., & Skov, M. W. (2016). Light grazing of saltmarshes increases the availability of nest sites for Common Redshank Tringa totanus, but reduces their quality. Agriculture, Ecosystems & Environment, 221, 71-78. 

Background

Distribution map from Bird Atlas 2007-11, which is a joint project between BTO, BirdWatch Ireland and the Scottish Ornithologists’ Club

In the United Kingdom, Redshanks are amber listed species of conservation concern, increasingly restricted in their distribution. The map alongside shows that breeding Redshanks have been lost from many areas (downwards pointing black arrows). More distribution maps from Bird Atlas 2007-11 can be found on the BTO Mapstore.

Although they breed in various grassland habitats, coastal saltmarshes are internationally important. The breeding population on British saltmarshes has reduced by over 50% since 1985. Declines have been linked to grazing management, as breeding densities are higher with light and moderate grazing than on heavily grazed or ungrazed saltmarshes (Norris et al., 1998; Malpas et al., 2013).

Intensive grazing leads to a very short, uniform sward, lighter grazing produces a more uneven patchy sward with diverse heights whilst no grazing can leave saltmarshes with dense communities of coarse grasses. For Redshank, which need clumps of grass in which to hide their nests and more open areas in which chicks can feed, light grazing is a key management tool.  Elwyn Sharps and his colleagues, working on the saltmarshes of the Ribble Estuary in northwest England, were interested to see just how light a grazing regime worked for the local Redshanks.

Working on the Wash, nearly twenty years previously, Ken Norris and colleagues had found that breeding densities were higher in structurally diverse grazed vegetation, and recommend low stocking densities of about 1 cattle ha^-1, in order to create a patchy vegetation sward, suitable for nesting Redshank. This falls within the UK Environment Agency definition of light saltmarsh cattle grazing of between 0.7 and 1 young cattle per hectare between April and October, which translates to an annual cattle density of 0.3 to 0.5 cattle per hectare per year.  Work on the Ribble suggests that light grazing can reduce nest survival both directly through nest trampling and indirectly through accelerating predation risks. Breeding densities may appear high in some areas but productivity can still be very low.

An earlier paper by Elwyn Sharps et al. showed that the risk of Redshank nest predation increased from 28% with no grazing to 95% with grazing of 0.5 cattle per hectare per year, which is still within the definition of light grazing. Some of the nest failures were due to trampling, with 1 out of 5 nests being affected in areas with the lowest stocking rates and 4 out of 8 in the most heavily stocked (though still defined as lightly-grazed) area.

What do Redshank need?

Crunch point: when a large foot meets a fragile clutch (Christine Tansey)

In lowland wet grasslands, Jennifer Smart demonstrated that Redshank select tall nest vegetation, with some additional cover in a wider 10m area around the nest. Elwyn Sharps investigated nest site selection by Redshank breeding in six lightly grazed saltmarshes around the Ribble in with cattle densities were between of 0 to 0.55 grazing units ha^-1 y^-1.  In May and June 2012, a total of 45 Redshank nests were found across the six saltmarshes (between 5 and 10 nests per marsh) and vegetation heights and species composition were measured at and in the vicinity of nests, as well as at control points.

Photo: Christine Tansey

On The Ribble, vegetation height was taller at, next to and in the wider area around nests, when compared to control points, for all spatial scales studied, in line with those found on lowland wet grasslands. The vegetation composition was different in the immediate vicinity and in the wider area around nests than at control points, indicating that Redshank select nest sites surrounded by particular species of vegetation. Most of the dissimilarity between nests and control points was due to red fescue (Festuca rubra), which was more abundant near nests than at control points. There is a suggestion from the Ribble data that Redshank select nests within communities of F. rubra, which is a species associated with cattle-grazing in higher elevation saltmarsh.

Implications for land management

Not quite long enough? Redshank nests are often completely hidden within clumps of grass (Kevin Simmonds)

The results of this study suggest that livestock grazing plays an important role in creating the F. rubra nesting habitat preferred by Redshank nesting on the Ribble Estuary. However, even low intensity conservation grazing can create a shorter than ideal sward height, potentially leaving Redshank nests more vulnerable to predators. Translating the UK Environment Agency light grazing guidelines of 0.7-1 young cattle per hectare between April and October to measurements used in this study would mean an annual cattle density of around 0.4-0.5 cattle per hectare per year, which this study suggests is too intensive for breeding Redshank.

Elwyn Sharps suggests that future solutions should focus on designing grazing regimes which increases sward heights for Redshank nesting. This could include delaying the start of grazing until most Redshank stop nesting in mid-July, but then grazing more intensively afterwards. This would allow vegetation to remain tall during the nesting season, but would still maintain a cover of F. rubra.

To read more about RSPB studies of breeding Redshanks visit this WaderTales blog (Kirsty Turner)

Another potential management solution may be a rotational grazing system, whereby saltmarshes are grazed and left ungrazed in alternate years, potentially improving habitat quality by allowing the vegetation to grow taller in the ungrazed year. However, on a small scale, Redshank may then select the part of a saltmarsh that was previously ungrazed , and therefore the area that will soon be grazed. It is clear that there are a number of possible solutions to this problem that require further investigations if the ideal saltmarsh management option for Redshank is to be ascertained. In working out how to manage saltmarshes for breeding waders, land managers will need to take account of the needs of other breeding species, overwintering wildfowl, and wider saltmarsh biodiversity, each of which may apply different constraints.

Sharps, E., Garbutt, A., Hiddink, J. G., Smart, J., & Skov, M. W. (2016). Light grazing of saltmarshes increases the availability of nest sites for Common Redshank Tringa totanus, but reduces their quality. Agriculture, Ecosystems & Environment, 221, 71-78.

And another problem…

In a more recent 2017 paper in Ecology & Evolution, Elwyn Sharps and colleagues show that cattle spend their time in the same areas of a saltmarsh as the ones in which Redshanks like to nest. Their conclusion is that “grazing management should aim to keep livestock away from redshank nesting habitat between mid-April and mid-July, when nests are active, through delaying the onset of grazing or introducing a rotational grazing system”.

Nest trampling and ground nesting birds: Quantifying temporal and spatial overlap between cattle activity and breeding redshank.

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

@grahamfappleton

All downhill for upland waders?

 

Are targeted payments for England’s upland farmers benefiting Curlew, Lapwing, Oystercatcher, Redshank and Snipe?

The farmed land that fringes our moors provides important habitats for breeding waders (Dawn Balmer)

In the period 1995 to 2013, England lost 32% of its breeding Curlew, 31% of its Redshank, 27% of its Lapwing and 14% of its Snipe*, according to the latest Breeding Bird Survey results. The uplands are the main stronghold for Curlew and hold (or used to hold?) significant numbers of the other three declining species. Is the story one of total gloom or are there areas where sensitive farm management and agri-environment payments are successfully supporting waders and other species associated with upland farms? A new survey, funded by Defra and coordinated by BTO aims to find some answers.

* Please note that the figures for population changes have not been updated. They all relate to the period 1995 to 2013. Latest figures can be found by following the link to the BBS results (see above).

The snappily-titled Breeding Waders of English Upland Farmland survey starts in April and volunteers are still needed in many areas. Please visit the BTO website if you may be able to help.

More about the key species:

Derek Belsey

Curlew (recent 32% decline in England). The species is globally defined as near-threatened and has been added to the red list of conservation concern in the UK. Losses have been particularly severe in Ireland, Northern Ireland and Wales but the distribution is shrinking in England. There’s a WaderTales blog about Curlew here. Is the Curlew really ‘near-threatened’?

Lapwing (recent 27% decline in England). Most of the work to try to understand recent declines in Lapwing numbers has been undertaken on lowland wet grassland, where cooperative mobbing of predators is an important part of the daily routine for parents. In the uplands, where breeding densities are lower, it would not be surprising if predation pressures could be impeding species recovery. There are two WaderTales blogs about these issues. A helping hand for Lapwings and How well do Lapwings and Redshanks grow?

Jill Pakenham

Redshank (recent 31% decline in England). The situation for Redshank is very similar to that for Lapwing, the presence of which may help in predator defence. There is a WaderTales blog about the special issues in the Uists (NW Scotland), where introduced hedgehogs are causing huge problems in this key wader hot-spot. Prickly problems for breeding waders

Snipe (recent 14% decline in England). The survey methods used in the new BWEUF survey are not designed to detect Snipe, which are mostly active at dusk, but the visits should provide useful count and distribution data for an under-researched species.

Nigel Clark

Oystercatcher (recent increase of 56% in England). Much of the increase may well be occurring in river valleys and newly created wetlands and gravel pits, rather than in the uplands. We know from the recent Moorland Forum report Understanding Predation that there have been changes in Oystercatcher abundance in much of upland Scotland between 1990 and 2010, potentially linked to predation pressure. It would not be surprising if similar processes operate in the English uplands.

How the BWEUF survey will work

Breeding wader populations in the UK have been a major conservation priority for some years. Declines continue despite the implementation of conservation measures that are designed to deliver appropriate habitats, some of which are supported through agri-environment schemes (AES). While enhanced monitoring of many upland and lowland habitats would be valuable, a particular gap is evident for in-bye farmland. This habitat can be defined as juncus/rush pastures, semi-improved pastures and meadows below the moorland line, although it technically includes all enclosed farmland. Using Defra funding, Natural England has commissioned BTO to run a volunteer-based survey, with RSPB field-staff filling gaps in less accessible areas.

Photo: Dawn Balmer

This project will assess the importance of in-bye land for waders, by estimating the total numbers present in these habitats, relative to national estimates measured from Bird Atlas 2007-11 data. More importantly, it will set a baseline against which to measure future change in breeding numbers.  This will be used to assess the success of Environmental Stewardship management, as well as to measure differences in numbers between AES and non-scheme habitats for waders that nest and/or forage on in-bye farmland. The survey will use 2×2km grid squares (tetrads), as in Bird Atlas 2007-11. Volunteers are asked to make two morning visits to each tetrad, one between early April and mid-May and a second before mid-July, with a minimum of a two-week gap between visits. On each visit, volunteers will be asked to survey as many as possible of the fields in this in-bye buffer of 1km below the moorland line. They will walk to within 100m of every part of each field to which they have access, recording all birds seen and heard, noting any display or territorial behaviour and mapping the locations of target wader species.

There’s an opportunity to record other species of conservation concer, such as this red-listed Yellow Wagtail (Jill Pakenham)

The key features of grassland management and structure, along with other land use, which dictate suitability for waders, will be recorded.  Predation has been identified as one potential driver of population decline – or an impediment to species recovery – so observers will be asked to record avian and non-avian predators.

Birdwatchers do not normally spend much time in this in-bye habitat so here’s an opportunity to capture as much information as possible, especially for any other waders and gamebirds (Black Grouse, Grey Partridge, Pheasant, and Red-legged Partridge). Valuable information can be data can be collected for Cuckoo, Linnet, Meadow Pipit, Reed Bunting, Ring Ouzel, Skylark, Stonechat, Twite, Wheatear, Whinchat and Yellow Wagtail, many of which are red-listed species of conservation concern (and bonus birds on a day’s birdwatching). To view further information on survey methodology follow this link.

In Summary

The wader declines quoted in this article use Breeding Bird Survey data from 1995 but there is evidence of longer-term falls for Curlew (55% since 1975), Lapwing (65%), Redshank (65%) and Snipe (90%). These are worrying numbers and it is to be hoped that the BTO can find enough volunteers for BWEUF, despite the fact that many of the survey squares are a long way from the flat-lands in which most English birdwatchers live. Curlews, Lapwings, Oystercatchers, Redshanks and Snipe are counting on us to count them.

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

@grahamfappleton

Spring moult in Black-tailed Godwits

Black-tailed Godwits will look and smell different by the end of May

A spring flock of Black-tailed Godwits at Cley (Pat Wileman)

Before they return to Iceland in April or early May, wintering Black-tailed Godwits have got a lot of extra feeding to do, both to fuel their journeys north and to undertake a complete change of body feathers. The grey plumage that has protected them since the autumn is discarded, to be replaced by summer finery. Although more colourful, these feathers provide cryptic camouflage in the habitats in which the birds nest – and they have less odour too.

There is a lot of individual variation but the timing of the spring moult of Icelandic Black-tailed Godwits seems to differ depending on the wintering area used by individuals. Many Icelandic birds that enjoy the sun in Portugal, for instance, can start to change colour before the turn of the year, but there is little red to be seen in British flocks until February or even March. We have the impression that there might be enough variation across Britain & Ireland to potentially pick up differences at this scale but we have yet to establish if this is true.

Full summer plumage in Iceland (Tómas Gunnarsson)

Some godwit observers have been scoring the moult of spring flocks of Black-tailed Godwits for years, especially for ringed individuals. This has given us quite a lot of data from a few sites, but spread over a number of years and a range of spring conditions.

We thought that we may be able to look at the regional differences more effectively if we could collect images from as many flocks as possible over one weekend. We chose Easter weekend 2016 to try this out, as we thought that this should give us as much variation as possible, with birds at several different stages of moult. Birds were scored from 1 (full winter) to 7 (full summer), according to the table below and images at the bottom of the blog, but all we needed was pictures from birdwatchers that we could then score. We had not reckoned on Storm Katie, which seriously affected opportunities to take photographs!

This was very much a pilot project. We know that we can score most birds when they are seen moving around, so that each bird gives a view of chest side and back. Could we capture this information from a sample of birds in two-dimensional pictures? If this worked, potentially we could have run a season-long project.

Spring moult

Cameras at the ready (Graham Catley)

There is a big difference between the winter and summer plumage of Black-tailed Godwits. Over the course of a few weeks, a grey individual turns into a thing of beauty. Camera shutters start to click in bird hides when a flock of birds sweeps back and forth, flashing white as the sun shines on bellies and underwings and then russet red as it catches their backs. It would be easy to think that these summer colours make Black-tailed Godwits more obvious, when they are nesting, but that’s not the case. In rusty-orange sedge-edged pools and when creeping their way through the red stems of dwarf willow on their way to a carefully hidden nest, they are very well camouflaged.

Plumage 6 (left) and 5 (right). Photo: Dennis Swaby

Most wading birds moult into a summer plumage in spring. For Black-tailed Godwits, this process involves body feathers, some of the small coverts on the wings, scapulars and a variable number of tertials. Their individuality is apparent from the richness of colour, the mixture of red, black and white feathers in the body and of grey and red feathers in the back. When the moult has been completed, male birds tend to be redder in the chest and neck and they have fewer grey feathers in the back than females, but there is an overlap. When sexing methods were checked against DNA samples it was shown that experienced observers could correctly assign sex to 82% of marked breeding birds in the field for which the sex was also determined by DNA. There’s an interesting paper about this in Bird Study. 

By mid-April Black-tailed Godwits in the UK are in virtually full summer plumage (Graham Catley)

Breeding waders don’t just look different – it has been suggested that they smell different too. Birds of a range of species, including Black-tailed Godwits, have been shown to produce a different preen gland oil with which to groom their summer plumage feathers, with monoesters replaced by diesters as winter feathers are discarded and pre-nuptial moult progresses. This was something that was first shown for Knot by Jeroen Reneerkens and colleagues and then for another eighteen species, breeding in both high Arctic and temperate conditions. In nesting birds, secretion of diester waxes continues through to egg-hatching, with the lowest occurrence of diester production in male Ruff and male Curlew Sandpipers. Given that these are the only two species in the sample under consideration in which males don’t incubate eggs, Jeroen et al suggest that diester preen waxes are harder for predators to detect using a sense of smell. You can read more here. When this theory was tested, using a sniffer dog, Jeroen showed that less volatile diesters were harder to detect. (paper)

Did it work?

This plumage 3 bird will soon be a plumage 4 – lots of new feathers are growing through on the breast (Pat Wileman)

Although we received fewer images than had been hoped (thanks Storm Katie!) we discovered that pictures are not enough. The clue may well have been in the protocol; we had asked for pictures of 25 to 50 birds so as to show the chest and back of each individual, and that was too tough an ask.

However, it’s still really helpful to receive plumage scores alongside colour-ring sightings so please keep those coming. Black-tailed Godwit colour-ring sightings can be sent to any of the scheme organisers. If you are not sure who your Black-tailed Godwit belongs to, Jenny Gill (j.gill@uea.ac.uk) is happy to act as a clearing house. There are some sample scores below.

Scoring Black-tailed Godwit moult

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

@grahamfappleton