Wetland Bird Survey: working for waders

Red-listed Curlews, Scottish Oystercatchers, a boom in Black-tailed Godwits and the need for safe roost sites. Here’s a selection of WaderTales blogs that may appeal to counters who contribute to the UK Wetland Bird Survey (WeBS) and other birdwatchers who like waders/shorebirds.

Blog RINGOS

It’s 70 years since UK birdwatchers started to count waders and waterfowl and there are now over 3000 registered Wetland Bird Survey volunteers.

WeBS70logo6a_smallThe work that volunteers do to chart the rises and falls of species as diverse as Redshanks and Whooper Swans provides a unique insight into the fortunes of our wintering waterbirds. As a tribute to the people behind the binoculars and telescopes, I highlight seven WaderTales articles that use WeBS data. Click on the links in bold if you want to read a particular story.

Curlew counts

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WeBS counts for Curlew in Great Britain between 1974 and 2016

In the blog Is the Curlew really near-threatened? WeBS counts are used to show how numbers have changed over the decades. There might have been a boost in numbers when Curlew came off the hunting quarry list in Great Britain in 1981 but declines in the last 15 years reflect issues birds face in the breeding season in many parts of their European range.

Internationally, Eurasian Curlews are classified as near-threatened and in the UK they are now red listed. WeBS counts in Northern Ireland, alongside I-WeBS counts in the Republic, were successfully used to argue for the cessation of shooting across the island of Ireland in 2012.

Scottish Oystercatchers

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Oystercatchers are unusual, amongst waders, in that they feed their young

Surely the Oystercatcher is one wader species that we don’t need to worry about? Although the blog Oystercatcher: from shingle beach to roof-top leads with nesting behaviour, WeBS counts are used to illustrate regional trends in different parts of the United Kingdom. In Scotland, there is concern about poor breeding success, while in parts of Wales and England, WeBS counts may provide a way of measuring the population-level effects of cockle fishing and diseases affecting shellfish.

oyc webs

Three very different trajectories for national WeBS counts for Oystercatchers since 1974

Mid-winter movements

figureThe annual WeBS report highlights the months in which counts are at their highest in different estuaries. For Knot, for instance, the highest counts on the Wash are in September, in other east-coast estuaries and on the Dee the peak is in December, whilst further north, in Morecambe Bay and the Solway, top numbers occur in January and February.

In Godwits & Godwiteers, which focuses on the superb work of observers who track the movements of colour-ringed Black-tailed Godwits, WeBS counts from east coast estuaries and the Ouse Washes illustrate the move inland that occurs as the winter progresses.

National patterns and local counts

blogGroups of WeBS counters who cover local estuaries will be the first to notice changes in the numbers of the key species that use their own sites. If the number of Dunlin drops, is that a local phenomenon or part of a national picture? Is there always a strong link between national declines (or increases) and site-based counts? Interpreting changing wader counts provides some answers. It emphasises just how reluctant waders are to change wintering sites between years.

High-tide roosts

horse-and-flockEvery WeBS counter will appreciate the value of a safe (undisturbed) roosting site, whether this be used by waders or by ducks and geese. In A place to roost, WeBS counts for Black-tailed Godwits are used to assess the national and international importance of an individual roosting site in northwest England. The main thread, however, is about the energy expenditure associated with sleeping (not very much) and travelling to and from a safe roost site (lots). An interesting add-on is the story of what happened to Cardiff’s Redshanks when the estuary was turned into a lake.

New recruits

If adult birds don’t change their winter homes then increases in local populations may well reflect good breeding years for wader species. 2017 seems to have been one of the good years for several species that breed in Iceland, particularly Black-tailed Godwits. WeBS counters should not be surprised if there are really high counts this winter.

T with BTGA great summer for Iceland’s waders puts this year’s productivity into context and gives an update on wader research that is being undertaken by the South Iceland Research Centre (University of Iceland), the University of East Anglia (UK) and the University of Aveiro (Portugal). If you have ever seen a colour-ringed Black-tailed Godwit, Ringed Plover, Oystercatcher or Whimbrel you may well find this interesting.

On the open shore

NEWS tableThe blog News & Oystercatchers was written to promote the Non-estuarine Waterbird Survey of 2015/16, or NEWS-III. There are a lot of waders on the shorelines that link the estuaries that are covered for WeBS and, every few years, volunteers are asked to count these birds. In NEWS-II (2006/07), it was estimated that 87% of Purple Sandpipers were to be found on the open shore (see table) with high numbers of several other species. There’s an initial assessment of the results for NEWS-III in the latest WeBS report and I look forward to writing up the results as a WaderTales blog, once a paper is published.

Links to blogs mentioned already

Many more to choose from

There are over 40 WaderTales blogs to choose from in this list. Four of these articles might be of particular interest to WeBS counters:

  • knot

    Knot migration

    Which wader, when and why? gives an overview of the migration of waders into, out of and through Britain & Ireland. The patterns help to explain why the peak numbers for Sanderling occur on the Wash in August, on the Dee in November and on the North Norfolk coast in May, for instance.

  • Bar-tailed Godwits: migration & survival  contrasts the different migration patterns of the two races of Bar-tailed Godwits that use British & Irish estuaries and explains the importance of colour-rings in the calculation of survival rates. On the other side of the world, Wader declines in the shrinking Yellow Sea shows how quickly numbers can change if the annual survival probabilities of adults fall. sum plum
  • The not-so-Grey Plover focuses on the Grey or Black-bellied Plover but the real story is about moult. British and Irish estuaries are important to huge numbers of moulting waders. WeBS counters often don’t have time to look at individual birds but, with the right camera, you can learn a lot about waders by checking out the right feathers.

Thank you

Blog Counter 1I use WeBS data a lot – in my blogs and in articles – and I appreciate the tremendous value of data collected each month by thousands of contributors. They monitor the condition of their local patches and have directly contributed to local, national and international reviews of the conservation status of wintering waterbirds. To every current and past WeBS counter – ‘thank you!’

There’s a (large) selection of papers using WeBS data here, on the BTO website. The Wetland Bird Survey is run by the BTO, in partnership with RSPB and JNCC (which acts on behalf of NE, NRW, SNH & DAERA), and in association with WWT.


 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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A great summer for Iceland’s waders?

As July 2017 turned into August, the first juvenile Icelandic Black-tailed Godwits started to arrive in the UK – soon they were everywhere. Had this been a good year for waders and wader research in Iceland?

juvvy blackwits

Flock of juvenile Black-tailed Godwits in Devon

An increasing amount of wader research is taking place in Iceland, much of which is part of an international partnership between the South Iceland Research Centre (University of Iceland), the University of East Anglia (UK) and the University of Aveiro (Portugal). Although the main focus has been on Black-tailed Godwits, Whimbrels and Oystercatchers, there is a lot more to this collaboration.

Winter into spring

january surveyThe spring season started early for Verónica Méndez, who is studying the migratory decisions made by Iceland’s Oystercatchers. About one third of these birds stay in Iceland for the winter but most are thought to migrate to Ireland and western coasts of the UK. By looking for colour-ringed individuals in January she was pretty sure that she would be sampling resident birds. There’s a blog about this project here. At the same time, sightings of migratory birds were being reported from the UK and Ireland.

Since 2000, there have been annual spring surveys of arriving Black-tailed Godwits. Jenny Gill and I arrived on 13 April and started our survey routine of regular visits to estuaries, wetlands and stubble fields in south and west Iceland. Icelandic birdwatchers cover other sites in the east and south of Iceland. The dates of the arrivals of individual birds have already contributed to a paper about what is driving earlier spring migration of the species, which is written up in this blog.

FrenchIn cold northerlies, migration from Ireland, the UK and mainland Europe was slow in 2017. This is something we have seen before and described in this blog about the appearance of large flocks in Scotland. A record number of Black-tailed Godwits – 2270 birds in total – were seen on the Scottish island of Tiree on 25 April 2017, including a minimum of 23 colour-ringed birds. We saw one of these birds four days later, fast asleep on a hay field near the south coast of Iceland.

Breeding studies

The 2016/17 winter had been relatively warm and wet in Iceland and the ground was not frozen when waders returned from Europe. The Black-tailed Godwits did not stay for long on the estuaries before moving inland to breeding territories.

The Oystercatcher project got off to an early start. oyc crossIn collaboration with Sölvi R Vignisson, Ólafur Torfason and Guðmundur Örn Benediktsson, the team colour-ringed 177 new adults and 144 chicks in a range of sites around Iceland. This year’s adults have white rings with two letters on the left leg and two colour-rings on the right, whilst chicks have grey instead of white. A smaller number of youngsters ringed in 2016 have green rings with engraved letters and some adults from previous years have green flags.

As part of a study to try to understand the migratory behaviour of young Oystercatchers, José Alves & Verónica Méndez have fitted GPS/GSM transmitters to a small number of big chicks. Which birds will migrate and what determines the strategy? Two birds have already made what appear to be exploratory trips around southwest Iceland, before returning to their natal sites.

FIRST2OYCSAt the time of writing (26 August), none of the birds with trackers has yet left Iceland but the first two colour-ringed birds have been seen in Ireland – an adult from the east and a juvenile from the south (see map).

Breeding studies of Black-tailed Godwits have been ongoing since 2001 and a small number of adults and chicks were ringed this year. This graph, which appears in the blog Why is spring migration getting earlier? showed that recent recruits to the population arrive in Iceland earlier than birds from previous generations.

timing hatching

Dates of spring arrival into Iceland of 46 individuals hatched in different years and subsequently recorded on spring arrival (reproduced from Gill et al. 2014)

Pressures on Iceland’s waders

tableIceland is hugely important for breeding waders. It holds about 75% of Europe’s breeding Whimbrel, over half of the region’s Dunlin and perhaps half of its Golden Plover. Although changes to the way land is farmed may have provided opportunities for some species, such as Black-tailed Godwits, intensification and the timing of operations have the potential to impact distribution and breeding success. A paper by Lilja Jóhannesdóttir was written up as a blog Do Iceland’s farmers care about wader conservation? and she successfully completed her PhD Links between agricultural management and wader populations in sub-arctic landscapes in June 2017.

T with BTGThe amount of woodland is changing in Iceland, with more forestry and shelter belts around summer cottages. This is an issue that was highlighted in an AEWA report published in the autumn of 2016. In the spring, Aldís Pálsdóttir started a new PhD at the University of Iceland, in which she will explore the effects of forestry on breeding waders in Iceland. Her first task in the field was to measure the effects of forest patches on breeding wader distribution, which involved walking over 400km of survey transects! Complementary work this summer by Harry Ewing, as part of his Masters in Applied Ecology and Conservation at the University of East Anglia, has explored how levels of wader nest predation vary with distance from forest patches. There’s more about the effects of woodland on breeding waders in this recent Lapwing blog: Mastering Lapwing Conservation.

Deploying and collecting geolocators to study migration

Geolocators provide a cost-effective way of collecting information on the year-round movements of individual birds, as long as birds can be recaught in the breeding season following the deployment of the tags. This blog summarises a useful paper about the safe use of geolocators.

whimbrelCamilo Carneiro is studying for a PhD at the University of Aveiro. His project, entitled Bridging from arctic to the tropics: implications of long distance migration to individual fitness, takes him to Iceland in the summer and to Mauritania and Guinea-Bissau in the winter time. By putting geolocators on Whimbrels in Iceland, he can establish the migration strategies of individuals. He has already mapped 96 migrations of 32 individual birds and we look forward to seeing the results from his studies. A flavour can be found here, in blogs about the migration of Icelandic Whimbrel and the first results of initial geolocator work by José Alves, one of Camilo’s supervisors.

RingoRinged Plovers that breed in Iceland are thought to spend the winter in southern Europe and northern Africa. Böðvar Þórisson has been studying breeding Ringed Plovers for many years, with recent work including using geolocators to explore the migration routes and timings of individuals. This year he managed to retrieve 7 of the 9 geolocators that he put on in 2016 – look out for a poster on this at IWSG 2017 in Prague. These birds had spent their winters in Mauritania, Portugal, Spain, France and southern England. 16 new tags were deployed during 2017, including a number on the same birds as in 2016.

RNPIn collaboration with Yann Kolbeinsson and Rob van Bemmelen, Jóse Alves and other members of the team have been using geolocators to study Red-necked Phalarope migration. Some birds migrate to the Pacific Ocean around coastal South America and the Galapagos but how do they get there and what is the timing of their movements? These two articles tell the story of one bird from Shetland (UK) and moulting flocks in the Bay of Fundy (Canada). Sixteen new geolocators were deployed but none of the ten deployed in 2016 were retrieved. Perhaps Red-necked Phalaropes are not that site-faithful?

So how good a breeding season was it?

2017 chick surveyAs described in this blog, the productivity of Iceland’s Black-tailed Godwits is closely linked to May temperatures – unless a volcano erupts. Each June, Tómas Gunnarsson collects information on the number of successful broods, based on a 198 km car-based transect through south Iceland. Repeating this survey in 2017 he discovered a record number of broods, adding the right-hand orange dot to the graph alongside. May 2017 was warmer than any spring during the study period covered for the IBIS paper and the number of June broods was higher too. It is not surprising that there are so many reports of juvenile Icelandic Black-tailed Godwits in Britain and Ireland this August.

For other species, where productivity is recorded in the same manner (Whimbrels, Oystercatchers and Golden Plovers), the 2017 season was also the best in the period since 2012. Perhaps other species, such as Redshank and Snipe, did well too? Will these cohorts of juveniles be big enough for there to be a detectable uplift in number on this winter’s I-WeBS and  WeBS counts?

sunset


 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

 

 

 

Waiting for the wind – spring flocks of Black-tailed Godwit in Scotland

When a flock of Black-tailed Godwit turns up on a Scottish island or lochside, in April or May, it’s probably a sign that the birds have aborted the Atlantic crossing to Iceland.

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On 24 February last year, on the Samouco saltpans on the Tagus estuary in Portugal, we saw an Icelandic Black-tailed Godwit wearing four colour-rings: red & lime on the left, green & green flag (RL-GGf) on the right. It had been ringed there on 10 August 2010 by José Alves so it’s not a surprise that it was in the same spot five and a half years later. In between times, on 29 April 2013, RL-GGf was one of 1520 Icelandic godwits counted on the Isle of Tiree, in the Scottish Inner Hebrides, by John Bowler and Graham Todd. Having encountered strong northerlies it had been forced to delay the Atlantic crossing. If you think back to the cold spring of 2013, it is not surprising that strange things happened that year. Northerlies delayed spring arrivals of African migrants in the UK but they also blocked the departure of wintering birds that were trying to fly to Iceland, Greenland and Northern Canada.

table & legendRL-GGf is one of our favourite Black-tailed Godwits. It happens to like a small estuary called Grafarvogur in Reykjavik, which Jenny Gill (University of East Anglia) and I monitor daily in the second half of April each year. We’ve seen this bird here in the springs of 2012, 2014, 2015 and 2016, on a total of 13 occasions. We have an arrival date for 2011 too, when he was spotted in Southern Iceland by Tómas Gunnarsson, our Icelandic collaborator, but there’s a gap in 2013, when we left Iceland while he was still on Tiree (see table). There are a couple of early spring records of this bird in the Netherlands, so this is where he probably spends March and early April every year, having left Portugal in February. In the last six years he has set off for Iceland in spring and only in 2013 was he seen in Scotland. He and other godwits that are forced to suspend migration are starting to give us insights into the hurdles that weather patterns can put in the way when birds are trying to travel north (Gill 2015).

Migration in a changing climate

We’ve been monitoring the spring arrival of Black-tailed Godwits in Iceland since 2000, and we’ve shown that colour-ringed birds have their own individual schedules: early birds always arrive early and late birds always arrive late. Differences in the exact date on which each individual arrives may be associated with the weather patterns each year, but individuals are remarkably consistent despite annually variable weather conditions. It therefore appears that individual godwits, like RL-GGf, have a preferred window in which to undertake the Atlantic crossing.

GLYX

Interestingly, although there is no evidence that individual birds have changed their arrival times in Iceland over the last 15 years, the arrival dates of the population are getting earlier (Gunnarsson et al. 2006). We’ve shown that this advance in migration is being driven by young birds recruiting into the breeding population on schedules which are earlier than those of previous generations (Gill et al. 2015). Ultimately, this is likely to be being driven by warmer springs and earlier nesting seasons. There’s a blog about this paper. 

Black-tailed Godwits on Tiree

with whooper

This Tiree Whooper Swan will also have been heading for Iceland

Over the years, the Isle of Tiree in the Inner Hebrides has proved to be a great place to pick up colour-ring sightings of Black-tailed Godwits. John Bowler, the local RSPB Officer, really enjoys watching out for their spring return when, as he comments, “hundreds can drop in on the loch-sides in full breeding dress”. The very first birds appear at the end of March and numbers increase into April, with often very large flocks occurring at the peak of passage in the last week of April and the first week of May. Birds are usually found on the grazed edges of machair lochs, with numbers declining through May and odd birds lingering to the middle of June. Given that between 1% and 2% of the Icelandic Black-tailed Godwit population wear colour-rings there is a good chance of finding a marked bird. With migration getting earlier, John’s godwit-watching season will probably get longer.

Godwits also appear on Tiree in the autumn but in smaller numbers. The first failed breeders appear in late June, followed by more adults in July and early August and then juveniles in late August through to October, with occasional stragglers in November and December. Young birds often use freshly-cut silage/hay fields on Tiree for foraging, in the same way that many will have done in Iceland as they prepared for the journey south.

Disrupted Migration

French

The orange flag shows that this Black-tailed Godwit had been ringed in France

Black-tailed Godwits are very site-faithful in every season of the year. However, although 63 different colour-ringed birds have been seen in spring by John Bowler and his colleagues, only one bird has been seen in more than one spring. This low number of repeat between-year sightings on Tiree, where looking for colour-ringed birds is part of the daily routine, very much suggests that birds seen here are dropping in out of necessity, rather than using the site as an annual staging post. The journey from south England or The Netherlands to Iceland is only just over 1000 miles, which is well within the capabilities for migrating waders in non-stop flight – as long as they do not encounter adverse weather conditions (Alves et al. 2012, Alves et al. 2013).

Scottish flocks of migrating Black-tailed Godwits do not only occur on Tiree, of course. On the peak day of 29 April 2013, when 1520 birds were counted on Tiree, 891 birds were also reported at Loch Gruinart on Islay. The 2411 birds in these two flocks constituted about 5% of the Icelandic Black-tailed Godwit population (Gunnarsson et al. 2005). Given that there were other colour-ringed godwits reported in Motherwell and on Benbecula, just how many Icelandic godwits were in Scotland on that day?

annual colour-ringsThe lack of predictability, when it comes to the potential locations of these spring flocks, makes it difficult to monitor patterns across different years. There are simply not enough places at which there are regular counts of birds each spring and too many places where flocks could choose to stop. Fortunately, reports of colour-ringed birds provide a surrogate for flock counts.  A quick analysis of the number of colour-ringed Godwits from Icelandic, Portuguese and E England schemes, seen in Scotland between the springs of 2011 and 2016 shows that there were records in every year but with a larger number in 2015, and by far the most records in 2013. None of the birds was seen in more than one spring, emphasising the random nature of these arrivals.

air flockThe colour-ring information provided by birdwatchers is making a huge contribution to the migration studies of Black-tailed Godwits. There are now Black-tailed Godwits in Scotland in every month of the year but sightings of colour-marked individuals in April and May are particularly helpful in helping us to identify the influence of weather conditions on spring migration and the migratory routes used by birds from across the winter range. Please report any of these observations to j.gill@uea.ac.uk who will pass on records to other colour-ring administrators. Details of the godwit work and the publications to which colour-ring observations have contributed can be found in a blog called Godwits & Godwiteers 

This article first appeared in Scottish Birds, published by the Scottish Ornithologists’ Club.

References:

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 

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

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 

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 

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

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


 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

 

Flyway from Ireland to Iceland

There are over forty WaderTales blogs so far. Here’s a selection that may appeal to birdwatchers in Ireland.

Irish header

The Ireland to Iceland air link opens in February and does not close until well into May, as swans, geese, ducks, waders, gulls and passerines head north. At the end of June it opens again, with the first failed breeders returning to Ireland. Species such as Oystercatcher and Black-tailed Godwit spend much more of the year in Ireland than they do in Iceland.

AA

Most Oystercatchers are being ringed with two letter engraved rings, along with two colour-rings: Photo Tómas Gunnarsson

The island of Ireland holds important populations of waders in the wintertime – everything from Grey Plovers from Siberia to Turnstones from Canada – but there is  special relationship with Iceland. It’s the next stopping off point for passage Sanderling, as they fly from Africa to Greenland, and the ultimate destination for lots of wintering birds such as Redshank and Golden Plovers.

Oystercatchers lead the way

A lot of the Oystercatchers seen around Ireland’s coastline breed in Iceland, as has been shown by the Dublin Bay Birds Project. Birds start moving north very early, as shown by the appearance of four yellow-ringed Dublin Bay birds in Tiree before the end of February this year. Migratory decisions for Icelandic Oystercatchers explains how a new Icelandic project is examining the costs and benefits of being a migrant. Irish reports of Icelandic colour-ringed birds are helping to provide answers – and the Dublin Bay birds are providing great additional data.

snipe-1Each autumn, Irish-breeding Snipe are joined by much larger numbers from the north and east. About a quarter of foreign-ringed snipe that have been found in the island of Ireland are of Icelandic origin, compared to just one out of 255 in England. Snipe & Jack Snipe in the UK and Ireland compares the migratory strategies of the two species and laments the decline of Common Snipe, as a breeding species.

whimbrel-mig-fig1Some of the last waders to use the Ireland to Iceland flyway are Whimbrels, many of which stop off in Ireland on spring migration. Whimbrels on the move summarises a paper about the movements of Icelandic, ringed Whimbrel. Since its publication, a new paper has shown that Whimbrel are able to fly between Iceland and west Africa in one jump but that they sometimes need to stop off on the way north. See Very rapid long-distance sea crossing by a migratory bird by José Alves and colleagues.

Black tailed-Godwits

WaderTales was invented as a way of providing feedback to colour-ring readers who focused on Black-tailed Godwits. There are 10 blogs about the species, some of which may well appeal to birdwatchers who have spotted colour-ringed birds anywhere between Belfast Harbour and the Shannon Estuary.

pairs-mapWe are all aware that migration is getting earlier but how does this happen? Monitoring the annual arrival of individual colour-ringed Black-tailed Godwits in Iceland may well have provided an answer. Why is spring migration getting earlier? reveals that it is new recruits into the breeding population that are setting the pace; they are reaching Iceland earlier than previous generations.

Another fascinating story that is revealed by colour-ringing is the synchronous arrival of the two members of breeding pairs of Black-tailed Godwits, even if one wintered in Ireland and the other in France. You can read more here.

Breeding Waders

WaderTales were developed in East Anglia so many of the articles about breeding waders have an English feel to them. Hopefully, some of the blogs will still appeal. Anyone trying to support breeding Lapwing populations might be interested in A helping hand for Lapwings, which also talks about Redshanks.

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There’s an Icelandic focus too and a new blog, which looks at the attitudes of farmers, will resonate with conservationists (scientists, birdwatchers and farmers) who are trying to work together to improve conditions for Irish breeding waders. As Icelandic farming expands, what are farmers prepared to do to support breeding waders, many of which are destined to spend the winter on Irish estuaries. See: Do Iceland’s farmers care about wader conservation?

Ireland – a special place for Curlews

Curlew e (2)

Curlews fly vast distances to spend the winter on the estuaries of Britain & Ireland (© Graham Catley)

Is the Curlew really near-threatened? considers the plight of breeding Curlew. It’s easy to understand why BirdWatch Ireland, RSPB, BTO and GWCT  are focusing on this species How long will it be until breeding Curlew are lost from Ireland, completely?

The threat to the Curlew is real, especially when set in an international context. Two species of curlew are probably already extinct and other members of the Numeniini (curlews, godwits and Upland Sandpiper) are facing a similar set of problems to those that probably caused the demise of the Eskimo Curlew and Slender-billed Curlew. Why are we losing our large waders? outlines the background to a global problem.

There’s a WaderTales blog that summarises a new paper from BTO and RSPB – Curlews can’t wait for a treatment plan. Although the analyses are based on British data, the results are highly relevant to Irish Curlews.

Conservation issues

Hundreds of  birdwatchers take part in the Irish Wetland Bird Survey (Republic) and the Wetland Bird Survey (Northern Ireland). These counts identify and monitor key sites for wintering waders – and wildfowl. Whilst mud  and sand-flats are, of course, important to waders, so are roost sites. A place to roost discusses the importance of safe, high-tide roosts, especially in terms of energetics. It has been estimated that the cost of flying to and from roosts might account for up to 14% of a bird’s daily energy expenditure. That’s something to think about next time you see a dog chasing off a flock of roosting waders.

Further reading

b-stubble-godwitsHopefully, this summary  gives a flavour of some of the issues being faced by Irish waders and the research to which they are contributing. There are already over 40 blogs in the WaderTales series, with one or two new blogs being produced each month. If you want to know how volcanoes affect breeding waders in Iceland, why Black-tailed Godwits wear colour-rings or if there are costs to carrying a geolocator have a look here.

And finally …

There’s a useful summary about wader migration to, from and through Ireland in Which wader, when and why?

GFA in Iceland

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

Do Iceland’s farmers care about wader conservation?

When working with Icelandic farmers to conserve internationally important wader populations, a shared understanding of beneficial practises may be more important than financial incentives.

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Species like Snipe, Redshank and Black-tailed Godwits have been squeezed out of lowland areas of countries such as the UK and the Netherlands by centuries of drainage, increasingly homogeneous landscapes and the introduction of quick-growing grassland monocultures. Adults have lost nesting sites, chicks have fewer feeding opportunities and pre-fledged youngsters fall victim to farm machinery. Do the same fates await waders in Iceland or might it be possible to work with farmers to leave space for birds?

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Pools, set within semi-natural lightly-grazed fields, are important

As part of her PhD at the University of Iceland, in collaboration with the Universities of East Anglia (UK) and Aveiro (Portugal), Lilja Jóhannesdóttir asked farmers what they think about having birds on their land, what their plans are for their farms, whether they might be willing to leave some pools and focus farming activities in areas less important for birds, and if farm subsidies might encourage them to be more proactive conservationists. The sometimes surprising results of this questionnaire have been published in Ecology & Society.

Reconciling biodiversity conservation and agricultural expansion in the subarctic environment of Iceland. Lilja Jóhannesdóttir, José A. Alves, Jennifer A. Gill  and Tómas G. Gunnarsson. Ecology and Society 22(1):16.

The Waders of Iceland

tableIn a recent report prepared by AEWA (Agreement on the Conservation of African-Eurasian Migratory Waterbirds), in response to concerns about the effects of afforestation on Iceland’s waterbirds, Dave Pritchard & Colin Galbraith say “Iceland is second only to Russia in its importance as a breeding ground for migratory waterbirds in the AEWA region. It supports the most important breeding populations in Europe for six species of waders, and is the second most important country for three.”

Data in the table alongside have been extracted from Annex 4 of their report, which was discussed at the 12th Standing Committee of AEWA in Jan/Feb 2017. Iceland is home to c 75% of Europe’s breeding Whimbrel, over half of the area’s breeding Dunlin and perhaps half of its Golden Plover. The importance of Iceland has increased with the collapse of wader populations in other countries.

Waders on farmland

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Spring flock of Black-tailed Godwit feeding in a stubble field

Farmed landscapes in Iceland provide opportunities for waders. In the spring, newly-arrived flocks of Golden Plover spread out over hayfields, Black-tailed Godwits target the previous year’s barley stubbles and parties of feeding waders can be seen in sedge pools on farms. During the breeding season, the application of fertilisers, especially in areas where volcanic ash deposition is low, increases soil productivity and wader densities, as was shown in this blog about regional productivity. Come the autumn, hayfields attract flocks of birds fattening up for migration. Despite drainage of an estimated 55% to 75% of wetlands in Iceland in the last seventy years, the country is still a great place for waders.

The amount of intensively-farmed land in Iceland is increasing, to some extent driven by rapid recent increases in the number of tourists, who consume milk products and meat. This can be seen in the ongoing development of hayfields, to feed cattle, and barley production, for pig-feed. There is concern that these developments will impact upon wader numbers, through the reduction in the amount of semi-natural habitat, especially in the lowlands, loss of pools and reduced landscape heterogeneity. On top of these changes, warmer temperatures allow earlier cuts of silage which increases the risk of killing wader chicks that nest within these fields.

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More and more semi-natural land is being lost to grass monocultures

Lilja Jóhannesdóttir’s PhD is focused on how birds use the gradient of habitats that comprise farmland in lowland Iceland – from more intensively farmed fields through to lightly-grazed, semi-natural habitats. The paper that forms the focus of this blog looks at farmers’ attitudes to the birds that share Iceland’s farms and their plans for the future. It then attempts to reveal the willingness and capacity of landowners to engage with conservation management practises.

The questionnaire

To understand the views of Icelandic farmers toward bird conservation, given the current potential for agricultural expansion, Lilja interviewed 62 farmers across Iceland, using a structured questionnaire. Some of the key findings are:

  • Over 60% of farmers are likely or very likely to increase their area of cultivated land
  • Over 90% of farmers think it is important or very important to have rich birdlife on their estates
  • About 60% would consider modifying grazing regimes to help birds
  • More than 80% would be unlikely or highly unlikely to consider changing the timing of harvesting operations.
  • More than 80% would be happy to consider keeping pools intact
  • Information on conservation needs are more likely to change attitudes than financial incentives

The information collected in the questionnaires was analysed by region and by the age of the interviewee but no strong patterns emerged. Older farmers seem to appreciate birdlife more than their younger colleagues but are no more likely to change their behaviours to support conservation objectives. The detailed figures are reported in the paper.

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Creating new hayfield to produce cattle-food is at the expense of areas of semi-natural land

The majority of the Icelandic farmers who took part in the survey plan to expand their agricultural land in the next five years, and this is likely to be driven further by increasing demands for farming products. This implies that conversion of semi-natural land into farmland is likely to greatly increase in the near future, with potentially severe and widespread impacts on the internationally important bird populations that currently breed in these areas. Such expansion could put Iceland on a similar trajectory to many other countries that have experienced substantial biodiversity declines on the back of agricultural intensification and expansion. On the positive side, Icelandic farmers like wildlife and the results suggest that if they are better informed about the consequences of their actions they might well try to modify plans in ways that reduce negative impacts. The possibility of financial incentives to off-set potential losses did not seem to influence farmers’ views, but the authors suggest that this might be because there is no tradition for farmers to receive subsidies for conservation action.

b-horsesA clear finding of the study is that farmers are unlikely to change the timing of agricultural operations in order to help birds. Perhaps this is unsurprising in a country with a very short growing season and where periods of settled weather are rare. With relatively few consecutive dry days, opportunities to mow and turn silage or hay crops just have to be taken. The timing of farming operations, such as harvesting/mowing, can be crucial for breeding waders because they can result in the destruction of nests, chicks, and adults during the breeding season. For example, advances in timing of mowing of hayfields in the Netherlands has meant that this now coincides more frequently with wader nesting and chick rearing, causing unsuccessful breeding attempts and leading to lower recruitment. There is more about the Dutch experience in this Ibis paper.

If Icelandic farmers are unlikely to delay operations, perhaps other strategies, such as mowing fields from the centre – as used in the Outer Hebrides to reduce Corncrake losses – might be more acceptable to farmers who are so constrained by the weather? Read more about the Corncrake issue here. 

The Future

b-whimbrelAs a signatory to international agreements on the conservation of birds and wetlands (Ramsar Convention, Bern Convention, Convention on Biological Diversity and African-Eurasian Waterbird Agreement), the Icelandic government is required to take action to protect the internationally important bird populations breeding in the country. Given that there is no strong tradition of using planning laws or centralised agricultural policy to influence farmers’ decisions, working with individual farmers might be the best way to deliver conservation objectives.

Farmers’ views on the importance of having rich birdlife on their land and their willingness to participate in bird conservation provide a potential platform to work with landowners to design conservation management strategies – and to do this before further substantial changes in the extent of agriculture take place in this subarctic landscape. With three-quarters of Europe’s breeding Whimbrel and about half of the Golden Plover and Dunlin dependent upon decisions made in Iceland, there is a lot at stake.

Reconciling biodiversity conservation and agricultural expansion in the subarctic environment of Iceland. Lilja Jóhannesdóttir, José A. Alves, Jennifer A. Gill  and Tómas G. Gunnarsson. Ecology and Society 22(1):16.

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 GFA in Iceland

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

@grahamfappleton

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Black-tailed Godwit pairs – the importance of synchrony

How long does a godwit wait around to see if last year’s mate will turn up?

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Newly-arrived Black-tailed Godwits. Time for a wash & brush up and then off to territory?

Colour-ringing enabled Tómas Gunnarsson to follow the lives of pairs of Black-tailed Godwits nesting near his parents’ home in Iceland. In this world, that is ruled by timing and opportunity, the pairings, divorces and re-pairings could form the plot for a TV soap-opera. The studies turned into a fascinating Nature paper that was written up in The Telegraph newspaper. The two main characters were christened Gretar and Sigga  by the journalist but they’re more commonly known as RY-RO and RO-RO.

A tale of two godwits

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How long should this godwit wait for its mate?

2002: Colour-ringed Black-tailed Godwits RY-RO (red yellow – red orange) and RO-RO bred successfully in Laugaras, in the inland part of Iceland’s Southern Lowlands. Come the autumn, they left Iceland. The female (RO-RO) probably spent the winter in Portugal, although she was only seen there in later years, and the male (RY-RO) opted for the somewhat colder conditions of eastern England.

2003: Next spring, RO-RO arrived on territory on 6 May, before her mate. She cannot have known whether he was late or dead when she made the decision to move in with a new male, who was later colour-ringed as OR-OO.  When RY-RO arrived back a week later, on 13 May, he had to find himself a new female (GG-YO), who had been paired to a different male in 2002.

2004: Come the spring of 2004, RO-RO and RY-RO arrived at the same time and got back together.

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Tómas Gunnarsson with one of the colour-ringed Black-tailed Godwits

This is only one story but it seems to illustrate that there are good reasons to nest with a partner that is well known to you. This could help to illustrate why individual godwits are generally very good at timing their arrival back on territory, to synchronise with their partners, as revealed in this Nature paper, published in 2005.

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

In the paper the authors described the return of pairs of Icelandic Black-tailed Godwits to Laugaras in the spring of 2003. Godwits generally arrive in Iceland over a one-month period, between mid-April and the middle of May.

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Each line joins the wintering locations of a pair of godwits

On average, previously paired males and females in the study arrived within 3.1 days of one another, despite the fact that males and females from the same pair had spent the winter on average about 1000 km apart and that there is no evidence that any pairs had met at passage sites prior to crossing the Atlantic. Arrival synchrony seems to be related to mate retention, as the only divorces occurred in two of the three pairs that arrived more than eight days apart.

Synchrony in timing of arrival on the breeding grounds may be important for retaining a mate from the previous year and avoiding a costly divorce – but how it is achieved is a mystery.

Warmer springs

Tómas Gunnarsson and his father, Gunnar Tómasson, have been studying the timings of spring arrival in south Iceland of a range of species since 1988. In a 2011 paper in Bird Study they estimated that the timing of arrival of the first black-tailed godwit moved earlier by about 5.5 days per decade over that period. Here’s a link to the paper.

graphAs this advance in spring timing of migration was already happening when Tómas was making observations of the paired birds in Laugaras in 2003, we were all interested to see whether the schedules of marked birds would advance in similar ways. Interestingly, we have been able to show that the timing of arrival of individual Black-tailed Godwits is actually not changing at all. There is year-to-year variation in the dates on which individuals arrive, but no trend. Instead it is new recruits into the population that are driving the earlier migration. There’s a blog about this here.

Whilst there are processes in play that mean new recruits are migrating earlier than their predecessors, there must also be reasons why time-fidelity is important for individual birds. Perhaps synchrony increases the probability that individuals will be able to nest with the same mate in subsequent years? This is hinted at by the fact that godwits have been observed to re-pair with previous partners if opportunities present themselves.

Potential benefits of re-pairing with the same mate

For Black-tailed Godwits, not enough is known about the benefits of retaining the same mate. Given that divorce events are rare, it would be hard to measure any consequences for productivity – even if the nests were easy to find and youngsters easy to track – neither of which is the case. For the moment, all that is available is evidence of divorce and the possibility that females will not wait for males that are late.

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Nests are well hidden

Black-tailed Godwits are long-lived birds, with breeding territories in which resources are generally predictably distributed, and a pair is likely to be familiar with local predator densities and distributions. Whilst one member of the pair is incubating the eggs, the other spends a lot of time looking out for potential predators, and this mutual protection may well confer benefits for the adults and the eggs. Perhaps knowing the behaviour of one’s partner is important during the incubation period?

The complexities of incubating eggs

If the daily routines associated with parental change-overs at the nest become established over time, might this be an important driver towards fidelity? Fast forward to a paper on shorebird incubation patterns, published in Nature in 2016 by Martin Bulla et al, which might provide some clues:

Unexpected diversity in socially synchronised rhythms of shorebirds Nature 540,109–113 (01 December 2016) doi:10.1038/nature20563

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This actogram from the Bulla Nature paper creates some wonderful patterns

This paper is the result of a collaboration between Martin Bulla and 75 of his wader biologist colleagues, all happy to share data on nest incubation patterns which Martin then analysed. This resulted in an amazing data-set of 729 nests from 91 populations of 32 shorebird species, from which Martin was able to report remarkable within- and between-species differences in nest incubation rhythms.

This study suggests that energetic demands are not an important ecological driver of incubation bout length, but instead that pairs have developed idiosyncratic incubation patterns, possibly as an anti-predation strategy. Effectively, risk of predation, rather than risk of starvation, may have a key role in determining some of the variation in incubation rhythms. This means that species that hide their nests (and themselves) incubate for longer and change places less frequently.

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Incubating Ringed Plovers change places frequently

Ringed Plovers, for instance, walk away from their eggs when a potential predator approaches and change places on the nest frequently. A male or female Redshank, on the other hand, will sit tight and brood for about six hours before exchanging with its partner. While partner A is hunkered down on the nest, partner B leaves the area, so as not to draw any attention to the pre-packaged protein that partner A is sitting on. If B is only going to return when A is ready for a surreptitious change-over then the activities of the two need to be well synchronised.

As the authors point out in the paper, although the context for this comparative study was diversity in biparental incubation, it is possible that diverse behavioural rhythms may also arise in other social settings (for example, in the context of mating interactions or vigilance behaviour during group foraging). These are other circumstances in which it may well be beneficial to know one’s partner.

What does this mean for RY-RO and RO-RO?

Perhaps fidelity and synchronicity are really important to Black-tailed Godwits? If only their nests were easier to find and nest success was easier to measure! For the moment, all that we know is that pairs of Icelandic Black-tailed Godwits are remarkably synchronous in their arrival times on breeding territory, and something important must have driven the evolution of such a finely tuned migratory strategy.


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

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

Black-tailed Godwits expand their range in Russia and Iceland

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

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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.

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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

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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

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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

Conservation implications of range expansion

Numbers of the islandica race of Black-tailed Godwits appear still to be rising but their European cousins (limosa) are in serious decline, especially in the Netherlands.  The recent colonisation of new areas in Russia does not necessarily mean that the 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.

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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

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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

 

Why is spring migration getting earlier?

In Iceland, young trend-setting Black-tailed Godwits are changing the timing of spring migration

Flocks of up to 5000 Black-tailed Godwits gather in Alftafjordur in spring: Tómas Gunnarsson

Flocks of up to 5000 Black-tailed Godwits arrive in Alftafjordur (East Iceland) in spring: Tómas Gunnarsson

In recent years, earlier arrival of spring migrants has been widely reported in birds as diverse as swallows and waders but it’s not a universal trend; species such as British Cuckoos and Icelandic Whimbrels have not changed their arrival dates.  Interestingly, many of the species that have not advanced timing tend to be those that are declining.  By thinking about the mechanisms that enable some species to take advantage of earlier spring warming it might be possible to explain how timings and population changes may be linked.

Are individual Black-tailed Godwits arriving earlier each spring? (Photo: Nigel Clark)

Are individual Black-tailed Godwits arriving earlier each spring? (Photo: Nigel Clark)

The simplest way for spring migration to advance would be for individual birds to change their arrival dates, arriving earlier now (either because they have departed earlier or migrated faster) than they did in previous years.  These changes could be facilitated by changes to weather conditions before, during or after migration.  In general, the arrival of short-distance migrant species has advanced more than long-distance species, which has led to suggestions that individual birds are able to assess conditions on their breeding grounds from afar, and to ‘fine-tune’ arrival accordingly. This could explain why long-distance migrants seem less well able to change their schedules than species which have less far to travel.

Figure 1: Changes in first spring arrival dates of six species of waders in southern Iceland from 1988 to 2009 (reproduced from Gunnarsson & Tómasson 2011)

Figure 1: Changes in first spring arrival dates of six species of waders in southern Iceland from 1988 to 2009 (reproduced from Gunnarsson & Tómasson 2011)

This pattern of advances in arrival dates, and greater advances in short-distance migrants is seen in birds arriving into Iceland each spring (Gunnarsson & Tómasson).   By monitoring the first dates of a range of migratory breeding species to the area around Laugarás, an inland village in southern Iceland, over the period 1988 to 2009, Tómas Gunnarson and Gunnar Tómasson showed that species which spend the winter further south than France showed no change in arrival, whilst those from further north in Europe were returning earlier.  The southern group included the only wader in the Gunnarsson & Tómasson study which uses this migration strategy, Whimbrel (see diagram).

GL-YX on a windy day in western Iceland. He has been seen in eleven years. Despite the vagaries of spring weather, his arrival dates have only been spread over nine days (standard deviation 3.5 days) and have not advanced over the period 2003-2015

GL-YX on a windy day in western Iceland. He has been seen in eleven years. Despite the vagaries of spring weather, his arrival dates have only been spread over nine days (standard deviation 3.5 days) and have not advanced over the period 2003-2015

One of the species that has advanced spring arrival (by about two weeks in the last two decades) is the Black-tailed godwit.  Since 2000, we have been recording arrival dates of individually colour-ringed godwits into coastal Iceland – giving us the opportunity to assess whether individuals have indeed brought forward their time of arrival.  By making regular visits to the same sites we have discovered that the dates when we first come across individuals are remarkably consistent.  Although the arrival of the whole population is spread over a five or six week period, the window in which a specific Black-tailed Godwit appears is generally predictable, whether he or she is a bird that we tend to first see in mid-April or mid-May.  There are annual differences, of course, which appear to be linked to periods of adverse weather during the period of the sea-crossing (Gunnarsson et al 2006), from departure points in The Netherlands, The UK Ireland, France and Portugal, but there is no significant trend.

Dates of spring arrival into Iceland of 54 individually marked black-tailed godwits recorded on arrival in between 4 and 8 years, from 1999 to 2012 (reproduced from Gill et al. 2014). Whether an individual arrives early (left-hand birds) or late (right), the sighting dates for each bird are highly consistent.

Dates of spring arrival into Iceland of 54 individually marked black-tailed godwits recorded on arrival in between 4 and 8 years, from 1999 to 2012 (reproduced from Gill et al. 2014). Whether an individual arrives early (left-hand birds) or late (right), the sighting dates for each bird are highly consistent.

timing pop v indivAlthough the arrival date for the population has been advancing at ~0.8 days per year (Gunnarsson & Tómasson 2011), there has been no trend in individual arrival dates (not significantly different to zero days per year); Gill et al. 2014.

Most of the godwit chicks were ringed by groups of volunteers led by Pete Potts and Ruth Croger (Photo: Tómas Gunnarsson)

Most of the Black-tailed Godwit chicks were ringed by groups of volunteers led by Pete Potts and Ruth Croger (Photo: Tómas Gunnarsson)

If individuals are consistent in arrival but the population is advancing, the advance must presumably result from new birds recruiting into the population being earlier-arrivers than recruits from previous years?  Fortunately, there is a second long-running set of data that’s available to answer this question, in a large part because of the efforts of Pete Potts and Ruth Croger of Farlington Ringing Group.  In the period 1999 to 2014, they organised teams of volunteers to ring Black-tailed Godwit chicks in Iceland, with the support of the Icelandic Natural History Museum.  Significant contributions to the total of over 350 colour-ringed chicks were also made by Tómas Gunnarsson and José Alves, while researching the breeding ecology of Black-tailed Godwits for the Universities of East Anglia and Iceland.

Dates of spring arrival into Iceland of 46 individuals hatched in different years and subsequently recorded on spring arrival (reproduced from Gill et al. 2014)

Dates of spring arrival into Iceland of 46 individuals hatched in different years and subsequently recorded on spring arrival (reproduced from Gill et al. 2014)

Wader chick mortality is quite high and there are further losses in the eighteen-month period between autumn departure from Iceland and the first return trip, eighteen months later, so it was wonderful to have a sufficiently big cohort of marked recruits to look at patterns and trends.  For this study, arrival dates for 46 individuals of known hatch year were available for analysis.  As can be seen from the graph, arrival dates of new recruits have been getting earlier, with birds hatched in the last decade arrive around two weeks earlier than individuals hatched in the 1990s.

There are several reasons why recent recruits may be arriving earlier than in previous years, but the most likely is that this is a knock-on effect of advances in godwit laying dates that have occurred in recent decades.  Icelandic godwits nest earlier in warmer springs, and the frequency of warmer springs has increased.  Early fledging may benefit new recruits, by increasing the time available for them to migrate south, locate a good winter site and be in condition to return early when they recruit into the breeding population (Alves et al. 2013 http://www.esajournals.org/doi/abs/10.1890/12-0737.1  http://dx.doi.org/10.1890/12-0737.1). As their arrival date will be consistent thereafter, the overall timing of arrival of the population will advance.

Will this young Black-tailed Godwit contribute to our understanding of the timing of migration? (Photo: Tómas Gunnarsson)

Will this young Black-tailed Godwit contribute to our understanding of the changing timing of migration? (Photo: Tómas Gunnarsson)

Many other studies of different species in which individuals are tracked during migration are showing similar levels of consistency in individual timing of migration.  What then is causing the variation among species in rates of advance?  Long-distance migrants typically arrive later on the breeding grounds and breed quite soon after arrival, while short-distance migrants can have quite large time gaps between arrival and laying, depending on conditions for breeding. Short-distance migrants therefore have more capacity to advance laying dates (because they are on the breeding grounds waiting for suitable conditions), while long-distance migrants, such as Whimbrels in Iceland, arrive later and so cannot breed earlier even in a warmer year. Advances in spring arrival dates may therefore result from advances in laying dates and associated benefits of early fledging for recruits, and lack of advance in long-distance migrants may be a consequence of arriving late and hence being unable to take advantage of early, warm spring conditions.

In the Icelandic subspecies of Black-tailed Godwit, which is expanding in both number and distribution, it is clear that young recruits to the breeding population are driving the advance in timing of migration.  We only know this because of the long-term programme of chick ringing by volunteers and because we have been able to record the timing of individual birds’ migratory activities over a large number of years.  Funding for this work has been provided by the volunteers themselves, NERC , Icelandic Research Council  and EU TMR.

This blog is based upon research presented in the following open access paper:

Gill, J.A., Alves, J.A., Sutherland, W.J., Appleton, G.F., Potts, P.M. & Gunnarsson, T.G. 2013 Why is timing of bird migration advancing when individuals are not? Proceedings of the Royal Society B. , 281, 20132161


 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

Migratory decisions for Icelandic Oystercatchers

New Oystercatcher research in Iceland aims to explain how migration patterns change over time and how individual behaviour may drive population change

Which Oystercatchers will cross the Atlantic and which will stay in Iceland? (Tómas Gunarsson)

Which Oystercatchers will cross the Atlantic and which will stay in Iceland? (Tómas Gunarsson)

Most waders leave Iceland in the autumn, with vast numbers heading for the British Isles, coastal Europe and even Africa.  Amongst the exceptions are hundreds of Oystercatchers which ‘tough it out’ in wintry conditions, thereby saving themselves two long trans-Atlantic flights and potentially ensuring that they are able to make a prompt start to the next breeding season. Why do some Oystercatchers migrate when others don’t?  Is it the same birds each year?  Do resident birds have a competitive advantage when it comes to choosing a territory and raising chicks, and do these chicks follow the same migratory strategy as their parents?  In an era of changing weather patterns, can birds change their migratory preferences and how does this happen?  These are some of the questions that are being tackled by Verónica Méndez, as she monitors the movements of colour-ringed individuals in a joint University of East Anglia (UK) / University of Iceland / University of Aveiro (Portugal) project.

Migration in a changing world

Throughout the world, the distribution, abundance and behaviour of species is changing, partially as a response to climatic change. Given that most bird protection relies on a legislative framework that is site-based, changes to bird distributions are going to make life challenging for conservationists.  Will today’s Special Protection Areas be fit for purpose in 20 years’ time?  As they look to the future, conservationists want to be able to set up a network of sites that can flexibly support migratory species, and this entails understanding why and how migratory patterns are changing and might change in the future.  Icelandic Oystercatchers may well provide an ideal model species through which scientists can learn how migratory decisions can influence individual fitness, population demography and species distribution.

“I’m sure that I started a nest scrape somewhere here”. Spring conditions in 2015 were distinctly wintry: Verónica Méndez

There are likely to be different pressures facing resident and migratory Oystercatchers.  Two birds that breed on adjacent territories might have completely different annual cycles.  The bird that spends the winter in Iceland will not have to migrate but its probability of survival may be reduced by harsher winter conditions, possibly with a more limited set of feeding options and certainly with shorter periods of daylight.  In mid-winter, there is 6hr 40 min between first light and dusk in Reykjavik but 9 hours in Bangor, North Wales.  Come the spring, however, the same bird will be well placed to take advantage if spring comes early, whilst his migratory neighbour will face a hazardous sea-crossing, perhaps being delayed by a fortnight or more if strong northerly winds set in.

Individuals matter

An adult Oystercatcher providing food for a growing chick (Tómas Gunnarsson)

An adult Oystercatcher providing food for a growing chick: Tómas Gunnarsson

Although patterns of change in migratory strategies can be detected by looking at timings of first arrival and counting flocks, these changes can only be explained if we understand what individuals are doing.  It will be interesting to see, for instance, if Icelandic-winterers pair up together and what their offspring subsequently do in their first autumn.  Oystercatchers look after their chicks for longer than most waders so perhaps youngsters will be more likely to adopt the strategy of their parents than other species?

To answer these and many other questions, Verónica and colleagues from the Universities of East Anglia, Iceland and Aveiro have been colour-ringing Oystercatcher adults and chicks on the breeding grounds between the north-west and southern lowlands of Iceland.  Both adults and chicks (when big enough) are ringed with two colour rings on the left tarsus and a flag above another colour ring on the right tarsus (metal ring goes on either tibia and is not part of the scheme).  See update below to learn about a second scheme.

Wintering flocks of Oystercatchers will be checked in Iceland but most of the colour-ringed birds are likely to have flown south.  The team therefore need birdwatchers around the British Isles and along the Atlantic coast of Europe to look out for these marked Oystercatchers and to report them to icelandwader@gmail.com

Catching adult Oystercatchers

The study season for an Oystercatcher fieldworker starts in April, when the first nests start to appear.  Once a full clutch of between 1 and 4 eggs has been produced, both parent birds take turns to incubate for between 3 and 4 weeks.  During this period it is possible to catch the adults by temporarily replacing the eggs with plastic eggs and setting a spring trap or walk-in trap over the nest.  Sometimes the second adult can be caught while the first bird is being ringed, as he or she settles down on the unattended eggs.

Juvenile wearing new colour rings: Verónica Méndez

Juvenile wearing new colour-rings: Verónica Méndez

Catching chicks is harder.  Although they can be metal-ringed at an early age, their legs are too short at this stage for additional colour-rings.  By the time that the youngsters are big enough they can run very quickly – or even fly – providing excellent entertainment for the ‘spotter’ in the research team, as the ‘chaser’ is often outwitted and out-run.

What has been learnt so far?

The first adult Oystercatchers were colour-marked in the summer of 2012 and more were ringed in 2013 and 2014.  In the winter of 2014-15, eight migratory individuals were seen in Ireland, Northern Ireland, Wales, Scotland and Shetland and five resident birds were shown to have stayed in Iceland. Additionally, five birds wearing BTO rings that they acquired in Ireland and Wales have been recruited to the colour-ring project, increasing the sample of known migrants.  By the end of 2015, over 200 adults had been colour-ringed, as well as about 100 new chicks, so there should be plenty of birds to look for this winter.

Breeding adult Oystercatcher: Tómas Gunnarsson

Breeding adult Oystercatcher: Tómas Gunnarsson

A century or more of metal-ringing has shown that Icelandic Oystercatchers migrate mostly to the British Isles and West coast of France, but some have been recovered in Germany, The Netherlands, Spain and Portugal, so please check out any Oystercatcher flocks you see in any of these countries.  Although most observations of colour-ringed Oystercatchers will be made during the winter months, young birds may well be spotted in the summer, as Oystercatchers do not start to breed until they are two or more years old.  If some juveniles winter in Iceland perhaps they might be able to breed at a younger age than their migratory cousins?  That would be yet another way for a change in strategy to not only impact on the fitness of the individual but also on the population demography and the overall migratory strategy of the species.

Oystercatchers are also being ringed with two letter engraved rings, along with two colour-rings: Photo Tómas Gunnarsson

Oystercatchers are also being ringed with two letter engraved rings, along with two colour-rings: Photo Tómas Gunnarsson

An update…

Oystercatchers caught in later catches have been ringed with white, grey or green engraved rings, alongside two colour-rings.  If you come across a bird with a yellow engraved ring then it is probably from a project in Dublin Bay.

When researchers from the two projects got together at the 2015 International Wader Study Group Conference in Iceland they realised that five more Dublin Bay birds could be added to the list of Icelandic breeders that are definite migrants.

Please check flocks of Oystercatchers and report any sightings to icelandwader@gmail.com

Photo: Tómas Gunnarsson

Photo: Tómas Gunnarsson


 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