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.

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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 a recent 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.

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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?

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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

Red-n-phal GFAMany 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

MUv116n2coverIdentifying 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 conservationSimeon Lisovski, Ken Gosbell, Maureen Christie, Bethany J. Hoye, Marcel Klaassen, Iain D. Stewart, Alice J. Taysom and Clive Minton. Emu. DOI 10.1071/MU15042

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.
waders and spume TGG

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 shorebirdsEmily 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.

 


GFA in Iceland

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

@grahamfappleton

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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?

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

In a new paper in Wader Study, Tómas Gunnarsson and Guðmundur Guðmundsson have analysed the ringing recoveries of Icelandic Whimbrel and demonstrated that many probably make non-stop flights from Iceland to western Africa.  The study also helps 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.  The full paper is available to subscribers to Wader Study but a summary is available here.

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.

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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

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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.

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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.

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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.

What next?

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Tómas Gunnarsson

This analysis of metal-ringed birds sets 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. 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.


 GFA in Iceland

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

@grahamfappleton

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.

Graham Catley Welney

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

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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.

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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 3rd and 4th January 2016. She was seen again on a Portuguese rice-field on 2nd February 2016. When she returns to the Nene Washes of Cambridgeshire she will find lots of islandica already in residence.

Limosa or Islandica?

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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

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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

flock in air

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

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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.


 GFA in Iceland

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

@grahamfappleton

 

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. 

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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

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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.

CattleWorking 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?

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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.

Redshank nest christine tansey

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

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Not quite long enough? Redshank nests are often completely hidden withing 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.

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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.


 GFA in Iceland

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

@grahamfappleton

 

 

All downhill for upland waders?

 

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

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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.

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:

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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?

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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.

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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.

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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.

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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.


 GFA in Iceland

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

@grahamfappleton

Spring moult in Black-tailed Godwits

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

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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.

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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!

moult tableThis 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

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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.

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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

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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 Jerooen Renerkeens 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 groups of birds in the sample under consideration that 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.

Did it work?

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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

better moult


 GFA in Iceland

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

@grahamfappleton

 

 

Godwits and godwiteers

This blog tells a few stories about individual colour-ringed Black-tailed Godwits and the ‘godwiteers’ who watch them on the estuaries of the east coast of England. They’re part of an international network of 2000 birdwatchers, contributing to some fascinating science. 

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The dots on graphs within scientific papers hide fascinating stories about individual birds. With the help of a small number of colour-ring readers, here’s an opportunity to eschew the statistics and to focus on a few of the Black-tailed Godwits that have been recruited to help answer scientific questions. The next colour-ringed godwit that you spot may have been hundreds of miles away just 24 hours ago or could break the longevity record for the species of 25 years. At the end of this blog there’s a list of 18 published papers, most of which could not have been written without the help of colour-ring observers – our ‘godwiteers’.

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WeBS data from 2009-14 illustrate how numbers change over the winter season (figures not adjusted to reflect a few gaps in coverage)

Over the last two decades, Dudley and Carol Hird have seen over 500 individual colour-ringed Black-tailed Godwits in Kent, Graham Catley has witnessed a huge expansion of the wintering flock on the Humber, David and Pat Wileman have co-ordinated daily counts and sightings at Cley, while Simon & Pat Cox, Ed Keeble and Mark Nowers have collected data in Essex – and turned the Mistley flock on the Stour estuary into an open-air migration display for the public.

There has been a fantastic rise in the number of Black-tailed Godwits on the east coast of England since the 1990s. Work led by Prof Jennifer Gill and published in Nature in 2001 showed that this expansion was an example of a buffer effect, with newly colonised winter sites being of lower quality than sites further south in the range. As you will read, winter flocks rarely experience the bitingly-cold weather that they did twenty years ago and birds have learned to take advantage of feeding opportunities on grassland, particularly on the Ouse Washes. Life on the east coast may well now be easier than it once was but it is still a lot colder than the sunny conditions experienced by godwits wintering in Portugal, for instance, as shown in this paper in Ecology.

Graham Catley on the Humber estuary

Graham has witnessed a huge expansion in the number of Black-tailed Godwits on the Humber. Many of the birds that are seen on this estuary in autumn and early winter turn up at Welney, on the Ouse Washes, in the period February through to April, where they moult into their summer finery prior to a migration of more than 1500 km to Iceland.

My old notebooks tell me that I saw 11 Black-tailed Godwits at North Killingholme Haven pits on August 20th 1969 but it was autumn 1989 before there were more than 50 recorded. Little did we know at that time just how things would change over the next 27 years. In autumn 1995 the peak count at North Killingholme was 178 on August 28th but significantly on that date I saw a bird with colour rings. Subsequent enquiries revealed that it had been ringed on the Eden Estuary in Fife in 1993 – and a second bird was seen the following week from the same scheme. In 1996 new birds were seen from a scheme in the Wash and my first contact was made with Jenny Gill, who has furnished me with detailed ringing and recovery information on what are now over 300 different birds seen on the Humber since those initial sightings. Autumn passage can see a high tide roost of up to 6400 birds at North Killingholme (probably about 10% of the Icelandic population) but seeing leg rings can be problematic, as birds often stand in deep water and flocks are spooked by local Sparrowhawks and Peregrines.

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This juvenile bird was ringed in northern Iceland on 17 July 2007 and photographed at Killingholme 2 months later. It returned to Iceland in 2009, to breed in the next fjord.

The Humber Estuary started to hold wintering birds in the late 1980’s and now there are up to 2500 birds from November through to February. Checking colour-ringed birds has shown us that there are complex movements of birds around the estuary but also around Europe. Some of our autumn birds appear for quite short periods before moving on south while others seem to move to the Wash and then come back up to the Humber for the winter. Many wintering birds move south to the Ouse Washes in late winter and early spring, before heading off for Iceland, while others have been shown to move cross-country to Lancashire and Ireland. We’ve seen individuals from schemes in Portugal, France, Ireland, Scotland, Suffolk, Hampshire and of course the Wash and Iceland. It is always great to catch up with a bird you have not encountered for a few years and bumping into individuals with new types of rings or combinations begs the question – is it from a new scheme or have they run out of combinations?

In practical conservation terms, observing the colour-ringed godwits on the Humber has provided a large amount of information on the birds’ favoured roosting and feeding areas and how different individuals use the estuary during the course of the year. It also adds a little spice to a day’s birdwatching – trying to get an accurate count of a large and mobile flock of charismatic waders, identifying old friends and new acquaintances and finding out what other exotic and not-so-thrilling parts of the continent they have visited on their phenomenal migrations.

David & Pat Wileman at Cley, Norfolk

Working our way south, the next site with a long-run of colour-ring sightings is Cley, on the North Norfolk coast. Not only do David & Pat Wileman collect daily counts and observations, they also record individual moult patterns, as birds change in and out of their summer plumage.

There’s already a blog about the Black-tailed Godwits of Cley here.

Godwit moulting

Three pictures of the same bird at Cley, moulting out of its breeding plumage. Photographs by Chris Cook, Pat Wileman & Richard Chandler

Ed Keeble on the Stour estuary, Essex

Ed Keeble is one of an enthusiastic team of colour-ring readers on the Stour. He combines observations with photography and evocative art-work. The Stour held large flocks of waders long before sites such as the Wash and Humber, with birds using the estuary in the autumn, winter and spring.

I’m lucky enough to have have been born and bred on a farm on the banks of the Stour, so my earliest birding memories are of watching godwits roosting on our fields in the mid -1970s, through a leather-bound brass telescope . We were very proud of the godwits because, at that time, the Stour flock was one of only two in the UK that regularly approached 1000. With no colour-rings we knew very little about them. The godwits used to endure ferocious winter weather in those days. I’ve even seen them “legless”- flying with their legs folded forward into their breast feathers to conserve heat.

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White rings can sometimes look orange, due to staining

Fast forward to the present day and I am still birding intensively on the Stour, but with improved optics. I had noticed colour-rings on the godwits for many years but had assumed that there were some scientists somewhere who busied themselves reading them and therefore that there was nothing to report. The moment of revelation for me was a talk by Jenny Gill, when I was surprised to hear that the scheme was dependent on public sightings and that we were positively encouraged to pester her, Pete Potts and other colleagues with sightings!

One of the most rewarding aspects of reading colour-rings on the Stour at Mistley is how common it is to find a casual birdwatcher who has seen a ringed godwit, has sent the sighting in and been absolutely thrilled to get an email back with details.  I’ve been told countless times with great pride that “I got an email back from a professor and my godwit came from Iceland.”   There’s no doubt that one of the things which sets this scheme apart is the prompt response to sightings and the willingness to spend time unravelling confused and inconsistent ring-readings from the likes of me. This must take ages, but generates a great deal of goodwill.

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YO-B/B connected university friends in Scotland and England

One of my favourite regulars is a bird I know as the Yob (Yellow Orange – Blue over Blue), who was ringed by an old University friend in Scotland and sent down south for my entertainment. I’m still very much in my apprenticeship when it comes to the dark arts of colour-ring reading, but beginning to learn the difference between faded red and orange, and that things which look orange or yellow may in fact be stained white.

One of the most fascinating local insights from the colour-ring returns is the number of godwits using the Stour.  Based on counts of flocks alone, we know that we have about 1,000 wintering in a normal season.  But, with over 50 colour-ringed individuals per year, we have learned that there is a high degree of turnover and that the river is probably used by more than 3,000 birds, including those stopping over in the autumn on the way to France, Portugal or Spain.  We also get periodic influxes of 1000 birds or more when the Ouse Washes flood in the winter. So, whilst we may not offer top-grade wintering habitat (not enough wet meadows), we are a very much a hub for godwits on the move.

Mark Nowers on the Stour estuary, Essex

Mark is one of many UK-based colour-ring readers to have followed the Black-tailed Godwits to Iceland. He happily shares his love of the birds with the many promenade-walkers, birdwatchers and swan-feeders at Mistley, engaging them with stories of the travels of ringed individuals – a bit like the Ancient Mariner, who ‘stoppeth one of three’.

Black-tailed Godwits have taken over my ornithological life since moving to work and live around the Stour Estuary in 2002. It was obvious from very early on that dedicated people were spending a great deal of time and effort ringing these birds and I felt honour-bound to let them know what I was seeing.

The platform for watching Godwits is Mistley, which is so good that the RSPB ran engagement events there for several years. Mistley is a popular promenade so, as well as people with a specific interest turning up, we have also collared passers-by who showed the merest hint of interest. It only took a few moments, having begun to explain the godwits’ migration story, for them to realise that it was worth their while stopping. We were able to crystallise things with the story of “Billy the Boomerang” (he keeps coming back!) – or LY-YW to his ringing friends. Almost without fail, every autumn and spring he reappears on the Stour Estuary; between times he spends the mid-winter period with Dudley & Carol Hird in Kent.

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LY-YW – photographed on the Stour by Liz Cutting, appearing in Mark Nower’s Iceland notebook in April 2004 and digi-scoped by Jenny Gill in April 2008, to illustrate a BBC blog

In 2004, I spent a week in Iceland with Pete Potts and a godwit ringing and resighting team. On the 20th April, one of the birds seen was our friend “Billy” from Mistley. Four years later, in 2008, I saw ‘Billy’ on 14th April at Mistley and he was seen by Jenny Gill and Graham Appleton at Eyrarbakki, on the south coast of Iceland, four days later. His arrival was described in a live broadcast by Graham for the World on the Move BBC radio series. Billy was ringed as an adult on The Wash in 1998, so being at least two years old at the time of ringing, he is currently 19 and still going strong. I know that, among the godwit ringing community, this is quite a regular occurrence but to the wider public, when you tell the story of the very same bird that you have seen in two different countries, the look of disbelief and amazement says it all.

Simon & Pat Cox on many Essex estuaries

As a ringer with some 55 years of experience, Simon Cox realises just how valuable each report of a ringed bird can turn out to be.  Working with his wife, Pat, makes it significantly easier to collect data from big flocks of birds.

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Team photo: Pat & Simon Cox, Mark Nowers & Ed Keeble. [Most colour-ring readers will be jealous of the facilities on offer at Mistley]

The Essex coast is a very convenient base for watching Black-tailed Godwits, as our estuaries hold some 4,000 to 5,000 birds in winter (out of an estimated total of only 50,000 Islandica birds – Bird Study, 2005) and higher numbers during peak spring and autumn passage. The Stour, Colne and Blackwater estuaries have been my principal ‘godwit sites’ and I have to date recorded over 300 colour-ringed individuals, with just a few at more distant locations on my various travels, usually accompanied by my wife Pat, who has been very helpful in spotting ringed birds, especially when we have been confronted by a large flock all feeding actively in various depths of water! We sometimes take turns in keeping a ‘scope’ fixed on those frustrating birds that stand on one leg so that the full colour combination is only partly visible!

We find the movements of individuals fascinating, especially when the precise timing of the movements can be demonstrated:

GO-OfW  Green orange – orange-flag white was ringed in France near La Rochelle on 23/09/09 and had been seen on 30 more occasions, twice in Iceland and the remainder in France before I saw it in Alresford Creek on 27/07/14. Vincent Lelong kindly emailed me to say it was back in France the following day.

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R8-GW

WO-L/W  I recall Jenny Gill asking me the time of my sighting of white orange – lime over white in Alresford Creek on 22/09/05. It transpired that approximately three hours earlier it had been at Freiston Shore, on the Lincolnshire section of The Wash!

R8-GW  Red eight (on white) – green white has been seen several times on the Blackwater. He winters on the Exe estuary in Devon but visits Kent during spring and autumn passage, which seems a long way round to get to and from Iceland but works for him.

Dudley and Carol Hird in Kent

The southeast corner of England is an interesting area in which to observe the comings and goings of Black-tailed Godwits. The proximity to French estuaries and position on flightlines between Iceland and Spain/Portugal add extra possibilities for godwit watchers. Many people have provided sightings from this area but Dudley and Carol Hird are the godwiteers par excellence.

On June 29th 2006 we sighted OR-W//W at Oare Marshes and reasoned that this must have been ringed for some scientific purpose and that we should check it out and report it.  Thank goodness for the Internet in helping us to find the source and setting us on the path to over 5,000 colour ring combination sightings of a range of species, up to the end of 2015.  As time went on we realised it was useful, even important, to understand the different schemes in use by ringers if we were to play our part in the study of migration.

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Feeding godwits on the rising tide at Conyer, on the Swales Estuary, with Elmley on the far shore (Dudley Hird)

We are lucky, here in Kent, in having a beautiful estuarine system at Oare and Conyer on the Swale, Funton and the whole Motney Hill area on the Medway and the large Allhallows area on the Thames, which can all contain large numbers of waders throughout the year.  Our main concern is with the Black-tailed Godwits, as Kent must be of major importance to them on passage and over-wintering.  Oare is primarily a roost site (much harder to check for rings) while all our other sites are used for feeding (both legs in full view).

With the help of Pete Potts, godwits have been caught and colour-ringed by Swale Ringing Group in Kent; at Kingsnorth Power Station on the Medway estuary and on the Swale estuary at Harty.  As a consequence of this, nearly 40% of our sightings are of Kent colour-ringed godwits.  It is quite exciting in that they ring one day at Harty and we see them the next day at Oare.

Our total number of individual Black-tailed godwit sighting records cover 479 individual birds, which must mean our estuaries service a lot of godwits in total.  In addition to the Kent-ringed birds, 23% have been ringed in Iceland, 10% in France and 10% on the Solent.  We also have sightings of godwits from Norfolk, Lincolnshire, Suffolk, Devon, Scotland, Northern Ireland, Portugal, Spain and the Netherlands.

One very interesting godwit was Y8-WG sighted at Oare on July 16th 2012. This adult male was in active primary moult when ringed in Iceland on July 10th, just six days previously. He had flown nearly 2,000 km with only seven out of ten main primary flight feathers – an extraordinary feat of migration.  He obviously came to no harm as we have seen this bird back in 2013, 2014 and 2015.  We have never seen this bird on Spring passage and, to our knowledge, do not know where it winters or the route it takes back to Iceland. There’s still plenty to find out.

As I write this, in January, we are approaching one of our busiest times, with godwits arriving from the south and staying for nearly three months, as they build up to almost full breeding plumage before departing towards the end of April to their breeding grounds in Iceland.  It will be exciting to see which birds have returned to Kent again.

John Parslow on the Ouse Washes

The flooded grassland of the Ouse Washes attract thousands of Black-tailed Godwits, especially in the late winter and early spring.

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Well-used field guide

There will be a separate blog about this critical area in due course but we would like to pay tribute to John Parslow (one of the authors of the Heinzel, Fitter & Parslow field-guide, published in 1972), who was the area’s most prolific colour-ring reader for over a decade.  John passed away in November 2015, having spent many a winter day scanning flocks of Black-tailed Godwits, particularly at Fen Drayton, which is not an easy site to work. He has left behind over 1600 records of nearly 300 individual godwits, which is a significant part of the database for the Ouse Washes. His data live on.

Sharing the science

Here’s a list of papers to which colour-ring readers have contributed – so far. Each one comes with a link to the paper:

  1. Gill, J.A., Norris, K., Potts, P.M., Gunnarsson, T.G., Atkinson, P.W. & Sutherland, W.J. (2001) The buffer effect and large-scale population regulation in migratory birds. Nature, 412, 436-438. DOI: 10.1038/35086568
  1. Gunnarsson, T.G., Gill, J.A., Sigurbjörnsson, Þ. & Sutherland W.J. (2004) Arrival synchrony in migratory birds. Nature, 431, 646-646. DOI: 10.1038/431646a
  1. Gunnarsson, T.G., Gill, J.A., Potts, P.M., Atkinson, P.W., Croger, R.E., Gélinaud, G., Gardarsson, A. & Sutherland, W.J. (2005) Estimating population size in Icelandic Black-tailed Godwits Limosa limosa islandica by colour-marking. Bird Study, 52, 153-158DOI: 10.1080/00063650509461385
  1. Gunnarsson, T.G., Gill, J.A., Petersen, A., Appleton, G.F. & Sutherland, W.J. (2005) A double buffer effect in a migratory population. Journal of Animal Ecology, 74, 965-971. DOI: 10.1111/j.1365-2656.2005.00994.x
  1. Gunnarsson, G., Gill, J.A, Newton, J., Potts, P.M. & Sutherland, W.J. (2005) Seasonal matching of habitat quality and fitness in migratory birds. Proceedings of the Royal Society of London B, 272, 2319-2323. DOI: 10.1098/rspb.2005.3214 
  1. Gunnarsson, G., Gill, J.A., Appleton G.F., Gíslason H., Gardarsson, A., Watkinson, A.R. & Sutherland, W.J. (2006) Large-scale habitat associations of birds in lowland Iceland: implications for conservation. Biological Conservation, 128, 265-275. DOI 10.1016/j.biocon.2005.09.034 
  1. Gunnarsson, T.G., Gill, J.A., Atkinson, P.W., Gélinaud, G., Potts, P.M., Croger, R.E., Gudmundsson, G.A., Appleton, G.F. & Sutherland, W.J. (2006) Population-scale drivers of individual arrival times in migratory birds. Journal of Animal Ecology, 75, 1119-1127. DOI: 10.1111/j.1365-2656.2006.01131.x
  1. Gunnarsson, T.G., Gill, J.A., Goodacre, S.L., Gélinaud, G., Atkinson, P.W., Hewitt, G.M., Potts, P.M. & Sutherland, W.J. (2006) Sexing black-tailed godwits: a comparison of behavioural, molecular, biometric and field-based techniques. Bird Study, 53, 193-198. DOI: 10.1080/00063650609461433
  1. Gill, J.A., Langston, R.H.W., Alves, J.A., Atkinson, P.W., Bocher, P., Vieira, N.C.,  Crockford, N.J., Gélinaud, G.,  Groen, N., Gunnarsson, T.G., Hayhow, B., Hooijmeijer, J., Kentie, R., Kleijn, D., Lourenço, P.M., Masero, J.A., Meunier, F., Potts, P.M., Roodbergen, M., Schekkerman, H., Schröder, J., Wymenga, E. & Piersma, T. (2008) Contrasting trends in two Black-tailed Godwit populations: a review of causes and recommendations. Wader Study Group Bulletin, 114, 43-50. 
  1. Alves, J.A., Lourenço, P.M., Piersma, T., Sutherland, W.J. & Gill, J.A. (2010) Population overlap and habitat segregation in wintering Black-tailed Godwits. Bird Study, 57, 381-391. DOI: 10.1080/00063651003678475 
  1. Gunnarsson, T.G., Sutherland, W.J., Alves, J.A., Appleton, G.F., Potts, P.M., & Gill, J.A. (2012) Rapid changes in the distribution of phenotypes in an expanding population of a migratory bird. Proceedings of the Royal Society of London B, 279, 411-416. DOI: 10.1098/rspb.2011.0939 
  1. Alves, J.A., Gunnarsson, T.G., Potts, P.M., Gélinaud, G., Sutherland, W.J. & Gill, J.A. (2012) Overtaking on migration: does longer distance migration always incur a penalty? Oikos, 121, 464-470. DOI: 10.1111/j.1600-0706.2011.19678.x 
  1. Alves, J.A., Sutherland, W.J. & Gill, J.A. (2012) Will improving wastewater treatment impact shorebirds? Effects of sewage discharges on estuarine invertebrates and birds. Animal Conservation, 15, 44-52. DOI: 10.1111/j.1469-1795.2011.00485.x 
  1. Alves, J.A., Gunnarsson, T.G., Hayhow, D.B., Potts, P.M., Sutherland, W.J. & Gill, J.A. (2013) Costs, benefits and fitness consequences of different migratory strategies. Ecology, 94, 11-17. DOI: 10.1890/12-0737.1
  1. Alves, J.A., Gunnarsson, T.G., Potts, P.M., Sutherland, W.J. & Gill, J.A. (2013) Sex differences in distribution and resource use in a sexually-dimorphic migratory shorebird. Ecology and Evolution, 3, 1079-1090. DOI: 10.1002/ece3.503 
  1. Gill, J.A., Alves, J.A., Sutherland, W.J., Appleton, G.F., Potts, P.M. & Gunnarsson, T.G. (2014) Why is timing of bird migration advancing when individuals are not? Proceedings of the Royal Society of London B, 281, 20132161. DOI: 10.1098/rspb.2013.2161 
  1. Gill, J.A. (2015) Encountering extreme weather during migration: individual strategies and their consequences. Journal of Animal Ecology, 84, 1141-1143DOI: 10.1111/1365-2656.12412 
  1. Gunnarsson, T.G., Arnalds, O., Appleton, G.F., Méndez, V. & Gill, J.A. (2015) Ecosystem recharge by volcanic dust drives large-scale variation in bird abundance. Ecology & Evolution, 5, 2386-2396. DOI: 10.1002/ece3.1523 

Please send reports of colour-ringed Black-tailed Godwits to Jenny Gill (j.gill@uea.ac.uk). She will reply with full details of any birds ringed on the Wash or forward your e-mail to colleagues running other schemes.


 GFA in Iceland

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

@grahamfappleton

 

Prickly problems for breeding waders

Spoiler alert – hedgehogs are the killers

Machair thinner (JC)

Hedgehogs – an unwelcome addition to the unique machair habitat  (Photo: John Calladine)

The chain of Hebridean islands from the northern tip of North Uist to the southern tip of South Uist are special places to visit in the summer. Nowhere else in the UK will you find higher concentrations of breeding waders. In 1983, Fuller et al. estimated that this region held a third of the UK’s breeding Dunlin and a quarter of its Ringed Plover. (Populations of breeding waders and their habitats on the crofting lands of the Outer Hebrides)

Catley Hedgepig

Photo: Graham Catley

The islands are still special but, as a consequence of the spread of hedgehogs, following the introduction of just four individuals in 1974, numbers of breeding birds have dropped dramatically. The addition of this extra predator, which can feed by day and night and possesses a coat of spines that can withstand aerial attacks by parent birds, has long been associated with the decline.  But how much of the blame lies with the hedgehog and what can be done to support wader populations?

Brief history

close up RP TGG

A quarter of the UK’s breeding Ringed Plover nest within the Outer Hebrides (Tómas Gunnarsson)

The Outer Hebrides, in north west Scotland, used to be a haven for breeding waders, many of which nest on machair, fertile coastal grasslands along the west coast.  It’s a mosaic of habitats that includes arable and pastoral farmland, pools and sand dunes. The waders that nest here have been subject to predation, from gulls, corvids, rats etc. but the hedgehog was an unwelcome addition. With no foxes or badgers to eat them, no fleas to carry diseases and a good supply of easily-accessible eggs, hedgehogs have thrived and spread.

Work in 1998, led by Digger Jackson, showed that the hatching success for Dunlin, Lapwing, Redshank and Snipe clutches was 2.4 time higher in areas from which hedgehogs had been excluded. This was published in the Journal of Applied Ecology in 2000.

Breeding waders were surveyed in 1983, when hedgehogs were restricted in their distribution to small parts of South Uist. By the time of the next extensive survey in 2000, hedgehogs were well-established across South Uist and Benbecula, and the first individuals had reached the southern end of North Uist Uist. In just 17 years, numbers of breeding waders declined by 39% in the areas with hedgehogs, while there was an increase of 9% in North Uist. There were differences for all wader species but particularly for Redshank and Lapwing. The results were published in Biological Conservation in 2004. A subsequent control programme, to assess whether eradication might be a practical option, was expected to arrest the decline in wader numbers and promote recovery. Sadly, population levels have not recovered as well as expected which begs the question – ‘are hedgehogs the only problem?’

Further large-scale surveys were carried out in 2007 and 2014

Walking transect cropped (JC)

Rob Fuller, walking a transect (John Calladine)

The 2007 survey is written up in Bird Study. (Changes in the breeding wader populations of the machair of the Western Isles. Scotland, between 2000 and 2007).

The 2014 survey is written up in Scottish Birds (Calladine, J., Humphreys, E.M. & Boyle, J. (2015). Changes in breeding wader populations of the Uist machair between 1983 and 2014. Scottish Birds 35: 207-215).

In the period between 1983 and 2014, the greatest overall proportional declines were of Dunlin and Ringed Plover (72% and 70% respectively). Snipe declined overall by 45% and Lapwing by 14% while, in contrast, Redshank increased by 8% and Oystercatcher by 74%. The changes were not the same in the zones with and without hedgehogs. The deviation in trends was most marked for Redshank (which increased by 91% in the northern zone, with fewer hedgehogs, while decreasing by 22% in the southern zone) and Snipe (much bigger decreases in the south). Dunlin and Ringed Plover declined markedly in both zones, though less so in the northern zone. Any difference in trends was less apparent for Lapwing, although it did appear that they may have fared less well in the southern zone.

Are hedgehogs the main problem?

Predation event 1 (SNH video grab)

A hedgehog ignores nest defence efforts of pair of Lapwing (screen-grab from SNH surveillance camera)

A recent report, prepared for Scottish Natural Heritage by a consortium comprising the British Trust for Ornithology, the James Hutton Institute and MacArthur Green Ltd., aims to quantify the importance of predation by hedgehogs, relative to that by other predators.  The report includes a summary of the changes in numbers for the various wader species during a forty-year period, based on occasional broad-scale surveys and more regular monitoring of specific study sites.  The focus, however, is on results from studies using nest cameras, temperature loggers and fixed point observations in the 2012, 2013 and 2014 breeding seasons, measures of disturbance, transect work to assess productivity, and some land use and habitat recording.

report coverCalladine, J., Gilbert, L., Humphreys, E.M., Fuller, R.J., Robinson, R.A., Littlewood, N.A., Mitchell, R.J., Pakeman, R.J. & Furness, R.W. 2015. Predation studies on breeding waders of the Uist machair: Final report covering fieldwork undertaken in 2012-14. Scottish Natural Heritage Commissioned Report No. 811. 

 

Hog on machair (JC)

A hedgehog in the half-light (John Calladine)

The principal aim of the study was to quantify the importance of predation by hedgehogs, relative to that by other predators, work that could support arguments in favour of continued and enhanced removal of these introduced predators. Cost-effective solutions may require lethal control, instead of or in addition to translocation. These are tricky decisions, especially when considered alongside the rapid decline in numbers of hedgehogs across much of the UK.

Main findings

survival table

Clutch survival rates

The latest study provides further evidence that predation by hedgehogs is having an ongoing impact on breeding success of wader nest on the Uist machair, at least some of which is additional to that of gulls, which take both eggs and chicks.

In North Uist (low density of hedgehogs) clutch survival rates were higher than on South Uist (high density of hedgehogs) for the four main study species – see table. Overall, in North Uist, 74% of

predation table

Confirmed and probable causes of predation

wader nests, where outcome was confirmed, successfully hatched chicks.  In South Uist only 45% of nests successfully hatched chicks.  Most observed losses in both areas were due to predators.

Hedgehogs were the most numerous nest predators identified using nest cameras and other evidence, accounting for over half of occurrences, with all confirmed instances of predation by hedgehogs occurring in the ‘high hedgehog density’ areas. In these high density areas, hedgehogs were responsible for 35% of nest failures. Although summer nights are shorter than in much of the UK, 45% of clutch incubations ended during darkness in high hedgehog density areas, compared to 29% in low density areas, again suggesting that mammals are the main predators, with hedgehogs the most likely culprits.

Predation event 2 (SNH video grab)

This Common Gull takes an egg – and may be back for more (screen-grab from SNH surveillance camera)

Although avian predators (gulls, raptors and corvids, which are diurnal predators) were recorded most frequently in the high hedgehog density areas, observers did not find a difference in the frequency of predation attempts by avian predators between these areas and areas with fewer hedgehogs. The number of successful attacks by avian predators witnessed during fixed point observations was small (24 in 460 hours of observations spread over three years) and more successful avian predation events were recorded in low hedgehog density areas (n = 15) than in high hedgehog density areas (n = 9), despite lower abundance of avian predators in the low hedgehog density areas. There is a suggestion that avian predation may, to some extent, replace hedgehog predation in areas with low hedgehog density, especially at the chick stage, but this interpretation is based on a small sample size.

Other potential causes of wader declines may be associated with land use changes within the machair. These are discussed in a 2014 Bird Study paper by Calladine et al.

Conclusions

hog-predated nest (David MacLennan)

Evidence of hedgehog predation (David MacLennan)

It is pretty clear that hedgehogs are causing significant problems for nationally and internationally important populations of breeding waders, two of which are red listed species of conservation concern (Lapwing and Ringed Plover) and the rest of which are amber-listed.  It is also clear that efforts to control hedgehogs have had limited success.

Eradication is a contentious issue. Hedgehogs may have been introduced but, having become established on the Uists, the species has attracted significant support from a number of animal protection organisations, members of which don’t want lethal control methods to be employed. Translocation – the current control method – is a costly alternative.

SNH has demonstrated a political will to try to tackle the hedgehog issue and has applied to the EU for funding for an eradication programme. There’s more about the Uist Wader Project  on the Scottish Natural Heritage website.

Given current financial constraints, EU funding seems to be the most likely way to deal with this man-made predation issue. Any eradication programme may rely on proving that translocated hedgehogs survive. If they don’t, then there is probably a choice between using lethal control or further losses of red-listed and amber-listed wader species. At that point, is there going to be the political resolve to embark on a plan to remove all of the hedgehogs? Wader biologists hope that funding can be found to tackle this prickly issue.


 GFA in Iceland

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

@grahamfappleton

Tracking waders on the Severn

Birdwatchers are being asked to help with some cutting-edge science, simply by reporting sightings of colour-dyed Dunlin and colour-ringed Curlew and Redshank.

Severn 1 WWT (2)

The Severn: an empty estuary or a food-rich haven? (Corinna Blake)

The tides that create unique feeding opportunities for waders and other waterbirds on the Severn can potentially be harnessed to produce large amounts of clean energy. New impact assessment work aims to see how a development that would bring big benefits to the local economy might be carried out with as little negative environmental side-effects as possible.

Colour ringed Curlew by Kane Brides

Birdwatchers are asked to look out for colour-ringed Curlew and Redshank (Kane Brides)

The Severn is a great place for birds, especially waders, attracted to the area by mud that has high densities of mud-loving invertebrates such as ragworms. It is designated as an SPA, because of its importance to wintering species such as Bewick’s Swan, Curlew, Dunlin, Pintail, Redshank and Shelduck, and the spring passage of Ringed Plovers. There’s more about the SPA on the JNCC’s website.

The British Trust for Ornithology and Wildfowl & Wetlands Trust scientists have been awarded a contract to undertake an Environmental Impact Assessment for the proposed Cardiff Tidal Lagoon  by Tidal Lagoon Power, with BTO focusing on waders and WWT on ducks. It’s a unique opportunity not only to inform conservation planning but also to answer questions about the winter ecology of some key species. The team aims to:

  • Validate and refine methods developed by Richard Stillman (Bournemouth University) that predict bird distributions from food availability. (It’s easier to map food distribution than to follow bird movements)
  • Understand patterns of movement of species that use the proposed development area and other key sites, such as the Gwent Levels.
  • Track birds in order to identify feeding and roosting areas that are used when birds are hard to observe – in poor weather, at night and at all stages of tide.
  • Work out how mobile birds are, in order to propose ways in which lost feeding opportunities might be replicated as close by as possible.

Tagging

Tag on Curlew back (head covered to keep bird calm) by Lucy Wright

Tags like this should reveal how waders and ducks use the Severn estuary. Curlew by Lucy Wright.

Tagging is an important part of the project. Four-gramme Pathtrack tags are being glued to the backs of a sample of Curlew, Redshank, Shelduck and (hopefully) Shoveler. These should stay on for a couple of months, during which time movements will be logged every 90 minutes and downloaded using UHF receiving stations set up around the Severn. These four species have been chosen because, for each, more than 10% of the estuary’s population lies within the proposed footprint of the tidal lagoon.

Colour-rings

Colour ringed Redshank by Emily Scragg

This colour-ringed Redshank may well breed in Iceland but which areas of mud-flat does it use in the winter? (Emily Scragg)

Tagged Redshank and Curlew are also being colour-ringed, alongside others that are not being tagged. By collecting reports of colour-ringed birds from birdwatchers, the BTO team will be able to monitor the efficacy of the tag down-load process and keep a track of movements when the tags stop transmitting. As an added bonus, the colour-rings may generate some new information about the breeding sites of waders that winter on the Severn.

Sightings of colour-ringed birds would be very much appreciated. Five rings have been used on both Redshank and Curlew. Please submit sightings (date time and ideally a six-figure grid reference) to Emily.scragg@bto.org who would also be interested in “ratio counts” of flocks of birds – simply the number of colour-rings and the size of the flock.

Colour-dyed Dunlin

The Severn Estuary holds an estimated 3.2% of the European wintering population of the alpina race of Dunlin, birds that breed from Siberia across to northern Scandinavia. Dunlin are too small to carry transmitters that can be used with base stations so the team has gone back to traditional picric dye in order to look at the mobility of flocks. Any sightings of colour-marked Dunlin will be appreciated by emily.scragg@bto.org. Where possible, please submit ratio counts broken up into yellow/orange on breast (adults), yellow/orange on the rump (juveniles) and unmarked birds, together with date, time and location (ideally with six-figure reference).

Colour-dyed Shelduck

shelduck Kane Brides

The neck of this tagged Shelduck will be dyed yellow before release (Kane Brides)

It’s not just waders.  Over 3,000 Shelduck winter on the Severn, which is more than 1% of the European population. A sample has been caught by WWT. Ringed birds have a yellow/orange dye mark on the normally white plumage on the neck/upper breast (between the dark green head and the brown breast band). No Shoveler have been caught yet but the aim will be to put a similar dye-mark on these birds too.  Sightings of dye-marked ducks should be reported to Ed.burrell@wwt.org.uk

Impact Assessment

The consortium of organisations that is working on this new tidal-power study is well placed to combine impact assessment with high quality wader science. By focusing on Curlew and Redshank, both red-listed species of conservation concerned, it is to be hoped that more will be learnt about the winter feeding ecology of these two species. The BTO team has already discovered that Redshank fly further at night than was previously thought and hope to get to understand some of the pressures facing Curlew, now classified as globally near-threatened (see separate WaderTales blog)

Severn 4 WWT

The Severn – Gareth Bradbury/WWT

This is not the first impact assessment work that has managed to incorporate research that increases the scientific understanding of wader behaviour and ecology. Two other examples are given below:

The Wash: Back in the 1970s, a plan to build huge reservoirs on the mud flats of the Wash, in which to store fresh water that might meet the growing demands of southeast England, led to a doubling of wader catching activity, intensive studies of their feeding ecology and complementary work on other taxa. Much was learned about the mobility of species within this huge estuary and the turn-over of birds within the annual cycle. A draft copy of the report is available on line at the NERC website 

Cardiff Bay: In the period 1989 to 2003, long-term studies took place to try to understand the impacts of closing Cardiff Bay and hence reducing the amount of tidal feeding area for waders. Following the development, it was shown that Redshank that had been displaced from the Bay were in poorer condition and had lower survival rates in subsequent winters.  There’s a summary on the JNCC website. The papers listed at the bottom of this JNCC web-page are essential reading for anyone trying to counter the ‘birds will simply go elsewhere’ arguments, which are sometimes put forward in favour of development work.


 GFA in Iceland

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

@grahamfappleton

Black-tailed Godwits expand their range in Russia and Iceland

Birdwatchers and farmers plot range-changes of Black-tailed Godwits

DSCN2519 (3).JPG

The Back-tailed Godwit has expanded it range in Iceland (above) and in western Russia (Tómas Gunnarsson)

A recent paper by Igor Popov and Dmitry Starikov in Wader Study, the journal of the International Wader Study Group, provides a glimmer of good news for those concerned about the huge losses of the nominate limosa subspecies of the Black-tailed Godwit.  At the same time as limosa numbers in the west of the range have been dropping by an average of 5% per year, there has been colonisation of areas of Russia that are beyond what was thought to be the northern edge of the subspecies’ range.  Over a similar time period there has also been a well-documented range expansion of the islandica subspecies, about which more later.

Popov I. & Starikov D. 2015. Recent northward expansion of breeding Black-tailed Godwits Limosa limosain NW Russia. Wader Study122(3): 173–183.

Layout 1

Wader Study is the journal of the International Wader Study Group

Black-tailed Godwit is classified as near-threatened by IUCN/BirdLife, as a result of widespread and rapid declines in numbers of limosa, the most numerous subspecies (Gill et al 2007).  These declines have been linked to agricultural intensification and changes in the timing of farming operations on grass fields in the breeding season, habitat changes and the destruction of wetland habitats in Europe and western Africa, where limosa birds spend the winter, and possibly hunting effects.  In contrast, the Icelandic subspecies has been increasing.  Tómas Gunnarsson and colleagues had previously mined long-term datasets, provided by Icelandic farmers, the Icelandic Natural History Institute and others, to show that the range of the islandica subspecies has expanded hugely over the last century.  Now Igor Popov and Dmitry Starikov have used similar detective work to show that the northern edge of the limosa subspecies is moving north.

Russia

Russian site

One of the new habitats used by Black-tailed Godwits in the Nizhnesvirsky Reserve (Igor Popov)

In some ways, the Russian research is quite conventional, in that the records upon which the study is based were collected by scientists and birdwatchers.  The region under consideration belongs to five administrative areas of the Russian Federation but the focus is the area surrounding St Petersburg, where reports go back to at least the end of the 19th century.  By delving into the records from the libraries of the Russian Academy of Sciences, the Russian National Library and the libraries of various local institutions, the authors were able to pull together a list of observations and to establish that Black-tailed Godwits were absent from other lists.  At the heart of the study is the Nizhnesvirsky Reserve where systematic observations have been made for fifty years.

In the late 1980s, four pairs of Black-tailed Godwits were observed in the Nizhnesvirsky Reserve with other records between 1997 and 2003.  At the same time, there were increasing numbers of sightings in the wider study area and from beyond its borders, where there had been reports from as early as the late nineteenth century through to the 1940s and 1950s, with the first breeding record in the 1970s.  There is now a small but apparently stable population in the reserve, an area in which mean April temperatures have risen from +2.2°C to +4.8°C over the period 1880 to 2015.  Within the larger study area, Igor Popov and Dmitry Starikov feel that it is likely that there have been similar colonisations in other locations, as birds have settled in small numbers within dispersed areas.  One factor that may have contributed to the ability of Black-tailed Godwits to expand their range northward in recent years is the replacement of large areas of the taiga forests across the whole of Northern Russia with more open habitats that suit the species.

Iceland

DSCN1827

A male Black-tailed Godwit, glowing in the late afternoon sun (Nigel Clark)

The documentation of the range epansion of islandica Black-tailed Godwits in Iceland owes more to the inquisitive nature of Icelandic farmers than to the observations of birdwatchers.  This is fortunate, as farmers operate throughout Iceland, whilst birdwatchers are few and far between.  As the species spread into new coastal areas, farmers could not help but notice the arrival of these noisy russet-red birds, feeding in hay fields, perched on fence-posts and careering around the skies in their acrobatic display flights.  The key thing that farmers did was to tell someone.  Many of their observations ended up at the Icelandic Institute of Natural History in Reykjavík, which encourages and collects submissions of natural history records from across Iceland.  Tómas Gunnarsson collated these records, together with others, in order to date the major patterns of colonisation of breeding sites by black-tailed godwits.  In total, 118 records were obtained from these sources, which enabled identification of dates of first or recent breeding for 65 individual breeding sites within 39 individual basins throughout Iceland. The earliest breeding date of these sites was used as the colonisation year for each basin and the general pattern of colonisation is summarised in the figure below.

godwit spread

2017 chick surveyAs in Russia, one of the drivers of the increasing Black-tailed Godwit population in Iceland could well be changes in spring temperatures. In this blog about the effect of temperature and volcanic eruptions on breeding success, there is a clear relationship between the number of successful broods and the temperature in May, as you can see in the figure alongside. You can read more about this in the paper:

Effects of spring temperature and volcanic eruptions on wider productivity. Tómas Grétar Gunnarsson, Lilja Jóhannesdóttir, José A AlvesBöðvar Þórisson & Jennifer A Gill. IBIS (2017) DOI: 10.1111/ibi.12449

There was an even warmer spring in 2017 – which explains the orange dot (top-right) in the figure above. There’s more about wader research in Iceland during the summer of 2017 in this blog.

Conservation implications of range expansion

Numbers of the islandica race of Black-tailed Godwits are still rising but their European cousins (limosa) are in serious decline, especially in the Netherlands. This blog reveals a 75% decline in numbers since 1967 and concludes with: “Although enormous amounts of money and effort have been expended to conserve continental godwits, our findings make clear that these have been ineffective or insufficient.”

The recent colonisation of new areas in Russia does not necessarily mean that the limosa Black-tailed Godwit will become abundant in its north-eastern territories.  It is still rare, and its numbers are only increasing slowly.  In Finland, which lies at a similar latitude, the breeding population was estimated at 20 pairs in the 1980s, 25–35 pairs in the 1990s (Vaisanen et al. 1998), and 40–60 pairs in the 2000s (Jensen 2007).  Such detailed estimates are not yet possible for the new breeding areas in Russia but, because all reports concern only small numbers, Igor Popov and Dmitry Starikov conclude that no rapid population growth has taken place to date.   Sadly, it appears that colonisation of northern areas is unlikely to be much compensation for losses elsewhere in the limosa range.

Layout 1To read more about the Russian range expansion:
Popov I. & Starikov D. 2015. Recent northward expansion of breeding Black-tailed Godwits Limosa limosain NW Russia. Wader Study122(3): 173–183.

Icelandic colonisation data are used in five papers:

When Icelandic farmers sent in their Jadrakan (Black-tailed Godwit) observations to the Natural History Institute the term ‘citizen science’ had not been invented.  Nearly 100 years after the first records, their sightings have not only chronicled the spread of the species, they have also facilitated the publication of some interesting – and varied – papers.

cover pics

Grabbing the front cover: citizen science is at the heart of research into the range expansion of Black-tailed Godwits

Double buffer effect: As the population of Icelancic Black-tailed Godwits has increased, birds have moved into areas of poorer quality breeding habitat as well as areas of poorer quality winter habitat. Gunnarsson T.G., Gill J.A., Petersen A., Appleton G.F. & Sutherland W.J. A double buffer effect in a migratory shorebird population. J Animal Ecology 2005, 74:5 965-971.

Seasonal matching: Black-tailed Godwits that breed in newly-colonised, poorer-quality breeding habitats tend to winter in poorer-quality wintering sites. Gunnarsson T.G., Gill J.A., Newton J, Potts P.M. & Sutherland W.J. Seasonal matching of habitat quality and fitness in a migratory bird. Proc. Biol. Soc. B 2005 Nov 7; 272(1578): 2319–2323.

Arrival times in spring: Individual godwits from traditionally used breeding areas, where average habitat quality and spring temperatures are higher, arrive in Iceland earlier than those which breed in recently occupied areas, where average habitat quality and spring temperatures are lower. Gunnarsson T.G., Gill J.A., Atkinson P.W., Gélinaud G., Potts P.M., Croger R.E., Gudmundsson G.A., Appleton G.F. & Sutherland W.J.  Population-scale drivers of individual arrival times in migratory birds. Journal of Animal Ecology 2006 75, 1119–1127

DSCN2134 (2)

Small males tend to occupy territories in traditional breeding areas (Tómas Gunnarsson)

Selection pressure: The size of male Black-tailed Godwits is highly variable and varies strongly in relation to the timing of colonisation across Iceland, with small males being absent from recently-colonised sites.  This is most likely to be a consequence of preferences females may have for small males (and good quality habitats). Gunnarsson T.G., Sutherland W.J., Alves J.A., Potts P.M. & Gill J.A.  Rapid changes in phenotype distribution during range expansion in a migratory bird. DOI: 10.1098/rspb.2011.0939

Migration strategies: Individuals experiencing more favourable winter conditions had higher survival rates, arrived on the breeding grounds earlier, and occupied better quality breeding areas, even when migration costs are substantially higher. Alves J.A., Gunnarsson, T.G., Hayhow D.B., Appleton G.F., Potts P.M., Sutherland W.J. & Gill J.A. Costs, benefits, and fitness consequences of different migratory strategies Ecology, 94(1), 2013, pp. 11–17


 GFA in Iceland

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

@grahamfappleton