Waders on the coast

The UK’s coastline is of international importance because of the numbers of waders that it supports. In winter it accommodates over a third of Europe’s wintering Oystercatcher, Ringed Plover, Bar-tailed Godwit and Knot, as well as an increasing number of Sanderling.

Wintering waders on the UK’s estuaries are counted every month but those on the 17,000 km of open coast are only counted once a decade. There are good reasons for this disparity, given the much higher development pressures on estuaries and the need for regular monitoring of sites that are designated and protected. However, this does mean that we have very little information about wintering Purple Sandpipers, the vast majority of which are not covered by monthly Wetland Bird Surveys (WeBS). Over three-quarters of the UK’s Ringed Plovers are missed too, along with over half of the Sanderling and Turnstones and nearly half of the Curlew.

The last Non-estuarine Waterbird Survey took place during the winter of 2015/16, as discussed in the WaderTales blog NEWS and Oystercatchers. Jenny Gill and I undertook counts on Great Cumbrae and along stretches of the Clyde coast, in Scotland, an area we had also covered for the 2006/07 survey. We were concerned to count only 84 waders in 2015, compared to 206 in 2006. Details are in the table alongside. We hoped that 900 other people, walking along a total of 9000 km of the UK’s coastline, had been more successful!

The paper summarising NEWS results for the whole of the UK and making comparisons with previous surveys in 1997/98 and 2006/07 was not published until 2021. In the intervening period, the counts were included in two papers about wintering populations of waterbirds in Great Britain and Ireland, that were discussed in Do population estimates matter? and Ireland’s wintering waders. This blog draws heavily on a Twitter thread from the Wetland Bird Survey and the BTO’s press release. The new paper is published in Bird Study.

The big picture

In December 2015 and January 2016, NEWS III volunteers walked along amazing, long, white beaches, surveyed rocky headlands and scrambled the lengths of boulder-strewn coves. Not every kilometre of the coast could be visited but the fact that 50% coverage was achieved meant that estimates could be made of the whole coastline of the United Kingdom, together with the Isle of Man and the Channel Isles.

In terms of absolute numbers, Scotland has consistently supported the majority of the population across all non-estuarine waterbird surveys for Oystercatcher, Ringed Plover, Golden Plover, Lapwing, Purple Sandpiper, Bar-tailed Godwit, Curlew, Redshank and Turnstone. Although this is likely to reflect the relative length of the coastline for Scotland (12,714 km) compared to England (2,705 km), Wales (1,185 km) and Northern Ireland (328 km), Purple Sandpiper, Curlew, Redshank and Turnstone still appear to show a bias towards Scotland.

Using the information collected during the survey, BTO scientists were able to extrapolate estimates of the numbers of open-coast waders in the different countries of the UK and its island dependencies (see table below). The results are published in the journal Bird Study and summarised in the table below.

To evaluate the potential importance of the open coast, NEWS estimates for Great Britain in 2015/16 were compared to average population estimates. For eight species, the open coastline accounts for over 20% of the winter population. The figure of 113% for Purple Sandpipers suggests that more birds may have been present on the coasts of the UK in 2015/16 than in an average year or that the population estimate needs to be revisited. There are no Lapwings or Golden Plover in the table below, as there is no recent, reliable estimate of the national wintering population for either species. The Greenshank line is in italics as the sample size is small.

Ten species are considered in detail in the following sections. The maps were downloaded from the BTO website on 20 March 2021 (https://www.bto.org/our-science/projects/ringing/publications/online-ringing-reports). Comparisons are made between results from the Wetland Bird Survey (WeBS) and the Non-estuarine Waterbirds Survey (NEWS).

Oystercatcher

26% use open coasts. 21% NEWS decline since 1997/98. (WeBS decline 22%).

In December 2015, as we walked around the coast of Great Cumbrae in the Firth of Clyde, pairs of Oystercatchers were already staking out their territories, probably not having travelled anywhere since the previous summer or perhaps even in the last twenty years! Wintering flocks that we saw may well have included breeding birds from inland sites in Scotland, from Iceland and from Norway, together with juveniles and non-breeding sub-adults. NEWS III found that densities of coastal Oystercatchers were highest in Wales but that this is the area in which there had been the biggest declines. Breeding numbers have fallen rapidly in Scotland, as you can read in Oystercatchers: from shingle beach to roof-top.

Lapwing and Golden Plover

There was a 68% drop in Lapwing figures between 1997/98 and 2015/16 and a 59% drop in Golden Plover. NEWS and WeBS counts of Lapwing and Golden Plover are difficult to interpret because birds move readily between the coast and inland fields, in response to local conditions such as lying snow and the wetness of fields. This is further complicated in more prolonged freezing conditions, when flocks of Lapwing fly west and south in search of feeding opportunities.

Grey Plover

3% use open coasts. 71% NEWS decline since 1997/98. (WeBS decline 41%).

The Grey Plovers that we see around the coasts of the UK in December and January breed in Siberia. It has been suggested that one of the reasons for the decline in numbers in Britain & Ireland may be related to new generations of youngsters settling in winter locations on the continental side of the North Sea – a strategy that may now work better, given that winters are not as harsh. It is interesting that losses on open coasts, which many would consider sub-optimal habitats, have been more marked than on estuaries. There’s a WaderTales blog about Grey Plovers.

Ringed Plover

82% use open coasts. 21% NEWS decline since 1997/98. (WeBS decline 47%).

Ringed Plovers are red-listed in the UK because of the decline in winter numbers and the importance of these islands of the hiaticula race. In NEWS III, the vast majority of UK birds were found in Scotland (see earlier table) but densities were highest around the coast of England.  Colour-ring studies in Norfolk showed that breeding individuals can adopt a range of migration plans – some marked birds never left the county and others had winter homes as far away as France, Scotland and Ireland. This dispersal is pretty typical of hiaticula race Ringed Plovers that nest in western Europe and southern Scandinavia. Other races travel very long distances (Well-travelled Ringed Plovers).

Curlew

42% use open coasts. 40% NEWS decline since 1997/98. (WeBS decline 26%).

Large numbers of Curlew arrive in the UK in the autumn, with a strong link between Finland and the estuaries of England and Wales. It is estimated that 20% of Europe’s Curlew winter within the British Isles and any change in numbers has significance for a species that is already listed as near-threatened by BirdLife International. The decline in numbers on open coasts has been greater than that seen in estuaries; it has been suggested that this may relate to the breeding origins of birds using different habitats.

Bar-tailed Godwit

15% use open coasts. 33% NEWS decline since 1997/98. (WeBS decline 21%).

Unlike Black-tailed Godwits, which seek out the gloopiest of mud, Bar-tailed Godwits are perfectly at home on sandy shorelines. Wintering birds are of the race lapponica; these breed in Northern Scandinavia, Finland and western Russia (more here). NEWS III tells us that there has been a larger decline in numbers in coastal areas than on estuaries, perhaps related to the relative suitability of the two habitat types.

Turnstone

68% use open coasts. 29% NEWS decline since 1997/98. (WeBS decline 29%).

Almost all of the UK’s wintering Turnstones are thought to be birds that breed in Greenland and Canada. Declines are consistent between NEWS and WeBS. A Northumberland study has shown that, as numbers have dropped, so birds have withdrawn into areas that are less disturbed by people and dogs (See Disturbed Turnstones). About three-quarters of the UK’s open-coast Turnstones are found in Scotland but they are more thinly spread here than in England.

Sanderling

69% use open coasts. 26% NEWS increase since 1997/98. (WeBS increase 8%).

As discussed in Travel advice for Sanderling, the UK is a pretty good place to spend the winter. Whether the same would have been true for previous generations of Sanderling, that were faced with much colder winters, is open to conjecture. Since 1997/98, the densities of Sanderling in Wales have increased by 712%, by 462% in Scotland and by 85% in England. How long will it be until Sanderling flocks successfully over-winter in Iceland?

Dunlin

6% use open coasts. 51% NEWS decline since 1997/98. (WeBS decline 38%).

Three races of Dunlin can be seen in the UK (as you can read in Which wader, when and why?). Wintering Dunlin are birds of the alpina race, arriving in the UK from Siberia, NW Russia, northern Finland and northern Scandinavia in the late summer. Open coasts around the UK are estimated to accommodate fewer than 20,000 Dunlin. To put this into context, there are six estuaries that each hold more than this total during the winter period.

Purple Sandpiper

Almost all on open coasts. 19% NEWS decline since 1997/98. (WeBS decline 34%).

The rocky coasts of the UK are home to Purple Sandpipers from the Arctic, with a suggestion that North Sea coasts south of Aberdeen mainly play host to birds from Spitsbergen and northern Scandinavia, with Greenland and Canadian birds more likely to be found further north and on the Atlantic coast. Coastal numbers have declined by 19%. The Highland Ringing Group has shown that the number of young Purple Sandpipers has been declining on the Moray Firth, suggesting a period of relatively poor breeding success for birds migrating from the northwest.

Redshank

22% use open coasts. 42% NEWS decline since 1997/98. (WeBS decline 21%).

Perhaps surprisingly, few Redshank cross the North Sea to spend the winter in the UK. Winter flocks are largely made up of home-grown birds and migrants from Iceland. The recent decline in Redshank numbers is thought to be a reflection of changing numbers of British and Irish breeders, although there are no monitoring schemes to provide information about Icelandic birds. Since 1997/98, the number of Redshank on open coasts has dropped by 42% but almost all of the losses have occurred in the period since 2007/08 (37% decline between 2007/08 and 2015/16). Redshank is currently amber-listed in the UK, reflecting falling breeding numbers, but ‘promotion’ to the red list cannot be far off. There is a WaderTales blog about the rapid decline in the number of Redshank breeding on salt-marshes: Redshank – the warden of the marshes.

Summary

The Non-estuarine Waterbird Survey 2015/16 revealed that there have been major declines in abundance of four species since NEWS II in 2007/08, only eight years previously: Lapwing (down 57%), Curlew (down 31%), Redshank (down 37%) and Turnstone (down 32%). Lapwing and Curlew are both red-listed in the UK. The only species to increase is Sanderling (up by 79%).

Given the magnitude of the changes revealed in NEWS III, it is unfortunate that this labour-intensive survey can only be carried out every eight to ten years. Ideally, it might be possible to survey at least a sample of sites on an annual basis. It is certainly to be hoped that funding can be found for NEWS IV within the next few years, and that volunteers will once more be prepared to count waterbirds on beautiful, if exposed, stretches of coastline.

The results of NEWS III are published in a paper in Bird Study:

Wader populations on the United Kingdom’s open coast: results of the 2015/16 Non-Estuarine Waterbird Survey (NEWS-III) and a review of population trends. Humphreys, E.M., Austin, G.E., Frost, T.M., Mellan, H.J., Boersch-Supan, P., Burton, N.H.K. and Balmer, D.E.

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

Plovers from the north

Despite its global distribution, the Grey Plover (or Black-bellied Plover in the Americas) does not get the attention it deserves, according to Andrew Darby, author of Flight Lines, a book about shorebird migration and Grey Plovers in particular.

Who would want to study a shorebird that is the first species to sneak away from its tundra nest when danger threatens, and that is hard to catch outside the breeding season? Fortunately, satellite technology means that a lot can be discovered by following just a small number of birds and this blog will focus on two individuals, setting their travels within a broader flyway context.

Flight Lines

Grey Plovers CYA and CYB are the stars of Flight Lines, a book by Andrew Darby which takes us ‘across the globe on a journey with the astonishing ultramarathon birds’. They were caught together in Adelaide’s Gulf St Vincent by members of Victoria Wader Study Group on 14 November, 2015. Here, they were carefully fitted with tags that were originally to be deployed on Bar-tailed Godwits. So starts a story that takes us from the south coast of Australia to islands off the north coast of eastern Siberia, via the Yellow Sea.

Andrew has not simply written a bird book; Flight Lines tells the sort of tale that I remember from school days, of how Cook and Magellan travelled the globe or Livingstone and Stanley ‘discovered’ Africa. Grey Plovers have been flying to the Arctic for millennia – from Europe, Africa, Asia, Australasia, the USA and South America. CYA and CYB are doing what their ancestors have always done. As we follow their journeys, Andrew tells us about the habitats these birds need, shares stories about the lives of local people who await their arrival, reveals the way that shoreline ‘development’ is impacting upon their survival and tells us about some of the ornithologists who are  encouraging governments and local communities to save space for the birds with black wing-pits (see picture below).

Territoriality

Grey Plovers travel vast distances across the globe but once they have arrived at their final destinations they are highly territorial – and not just in the breeding season. When David Townshend studied marked individual Grey Plovers feeding on the Tees, in north-east England, back in the late 1970s, he discovered that they fed in the same places for the four-month period of the winter, defending their patches against interlopers; what’s more, they returned to these territories in subsequent years. It’s like running a marathon and then not leaving your back yard until it’s time to take off again, months later.

As Andrew Darby reminds us, Grey Plover can re-visit the same territories for decades; something to remember when considering what happens when a coastal development steals the ‘homes’ of all of the Grey Plovers in a bay. How does a twenty-year old bird find a new home? There’s a WaderTales blog about longevity records for waders/shorebirds.

Territoriality is not just a British thing. In Flight Lines we learn that the same is true for American Black-bellied Plovers wintering in San Diego and Grey Plovers in South Africa’s Eastern Cape. Here, tracking has shown that the patterns that David Townshend witnessed by day are maintained during the night. Those big eyes can make the most of low light-levels. A hungry individual stands still and waits for prey to move, gives up after a while and tries another likely patch within its territory. Plovers are not like Knot; they don’t have a sensitive tip to the bill that can detect hidden prey, their hard-tipped bills grab items from the surface of the mud or sand, guided by those big, black eyes.

Global distribution

According to BirdLife International, the global population of Grey Plover is only about half a million birds, 80,000 of which use the East Asian-Australasian Flyway. This system of aerial ‘motorways’ links countries as diverse as New Zealand and Thailand with breeding areas in the East Russian Arctic and Alaska.

There is a temptation to sit at home and think of migration as something that happens in a line that runs north to south and back again. Fifty years ago there was an assumption that Black-bellied Plovers would migrate north and south within the Americas, that Grey Plovers in western Europe and Africa would be linked to western Siberia, that Australian birds bred in eastern Siberia, and that Grey Plovers in southern Africa, the Arabian peninsula, India etc  would be birds that had flown from ‘the middle bit’ – between western and eastern Siberia.

Studies of other shorebirds have shown more cross-overs than might have been expected, breaking up the neat south-north pattern. Chukotka, for instance, indicated by the red star on the BirdLife map, is a summer home for Ringed Plover from Egypt (Well-travelled Ringed Plovers), Spoon-billed Sandpipers from Bangladesh, Knot from Australia and Buff-breasted Sandpipers from South America.

Shorebird mixing happens on the other side of the Bering Sea too. Shorebirds that fly to Alaska from South America in spring are joined by Bar-tailed Godwit that fly north from New Zealand, via the East Asian coast. These baueri race Bar-tailed Godwits are famous migrants – they fly non-stop all the way to New Zealand come fall/autumn. See paper by Phil Battley et al.

So, what about Australian Grey Plovers? Do they meet up with American Black-bellied Plovers?

Linking wintering and breeding areas

As Andrew Darby tells us in Flight Lines, measurements of Grey Plovers in Australia and in Russian breeding areas suggested that wader experts Clive Minton and Pavel Tomkovich were handling the same birds in Victoria and on Wrangel island, north of the Russian mainland. In 2007, Pavel banded some Grey Plovers, the hope being that one of them might be seen in Australia. The only one of these Grey Plovers ever to be reported was seen in the Chinese part of the Yellow Sea – six years later.

The Grey Plover colour-ringed by Pavel was spotted by David Melville, who has done a great deal to fill gaps in knowledge about the vast flocks of waders that use the Yellow Sea, including significant numbers of passage Grey Plover. One of the wonderful features of Flight Lines is the way that it turns names into characters. I had heard of many of the people who Andrew met or spoke to, during research for the book, but I appreciate their roles much better now. There is fantastic work taking place in countries throughout the Flyway, ably coordinated through the East Asian-Australasian Flyway Partnership.

Given that colour-ringed Grey Plovers were not providing the data that could link breeding and wintering grounds, it was time to try something new. On 14 November, 2015, CYA and CYB were fitted with satellite transmitters and in March they flew north. In the same way that we read that Captain Cook ‘discovered’ Australia, without telling the story of the challenges his crew faced on the way, I am just going to present the map of the northward journeys of the two birds and leave you to read Flight Lines, the log-book of their journeys.

The map shows the positions on 7 June 2016, when CYA and CYB had only just arrived on Wrangel Island. The journey north is described by Tony Flaherty in Victoria Wader Study Group Bulletin number 39.

“The two satellite transmitters, put on to Grey Plover in South Australia by Maureen Christie’s team in November, 2015, have performed brilliantly, with both birds successfully migrating northwards, including a long stop-over in the Yellow Sea, and eventually going on to breed on Wrangel Island off the north coast of Chukotka, eastern Siberia. This is the first evidence of any bird from Australia visiting this remote Arctic Island. At the time of writing this, both are now on their way back from the Arctic, with one having made a surprising major detour via the New Siberian Islands.”

There is a complementary article about the journey south in the next issue of the VWSG Bulletin, also by Tony Flaherty.

Map data courtesy of Victorian Wader Study Group & Friends of Shorebirds SE. The project was made possible by support from the Australian Government and the Adelaide and Mt Lofty Ranges Natural Resources Management Board.

A conservation agenda

One of the major drivers of bird ringers/banders is a thirst for knowledge – and there is nothing wrong with that spirit of enquiry. For the East Asian-Australasian Flyway there is a deeper imperative; conservation of birds using habitats that are under immediate threat from human exploitation and climate change. A previous WaderTales blog – Wader declines in the shrinking Yellow Sea – focuses on a paper that highlighted the desperate need to understand and conserve shorebird populations. One species that hardly gets a mention in that paper is the Grey Plover. It’s not that there is no threat to Grey Plovers, it’s just that there were insufficient data. It’s not easy to study these territorial plovers, which are thinly spread throughout the non-breeding range and difficult to catch.             

About Flight Lines

The WaderTales blog series started out as a planned book about Black-tailed Godwits but I found that I did not have the stamina to weave together science tales into an interesting tapestry. Andrew Darby is a master of the writing craft. Although he focuses upon waders, and the Grey Plover lead characters, he also tells us about the pioneer ornithologists who have explored the East Asian-Australasian Flyway, in search of shorebirds that spend Christmas and New Year in Australia and New Zealand. Flight Lines is published by Allen & Unwin. ISBN 978 1 76029 655 1

Migration research about other Grey Plover populations

Papers about Grey Plover and Black-bellied Plover are thin on the ground but new projects on the East Atlantic Flyway and in the Americas are starting to fill in some of the gaps in our knowledge.

The Wash Wader Ringing Group has ringed/ banded over 6500 individual Grey Plovers since the Group was founded in 1958 (Sixty years of Wash waders). Their work was written up in 1976 by Nick Branson and Clive Minton (Moult, measurements and migrations of the Grey Plover). The map alongside shows movements of birds to and from the Wash.

Recent research by Klaus-Michael Exo and colleagues has used satellite tracking to understand better the movements of Grey Plover breeding in the Taimyr and Yamal regions of Siberia. In their paper, they identify important staging sites as well as wintering areas between Ireland and Guinea Bissau. Tagged birds stopped off for long periods during migration, especially in late summer and autumn. See Migration routes and strategies of Grey Plovers on the East Atlantic Flyway as revealed by satellite tracking.

The Tidal Wings project focuses on Grey Plovers that winter in the Bijagos archipelago of Guinea Bissau. You can keep up to date on their discoveries on their website (https://birdecology.wixsite.com/tidalwings) and on Twitter. The map above shows three migrations of the same individual.

In North and South America, the Black-bellied Plover is also receiving increased attention. There is a large collaborative project to reveal their migratory connectivity, with over 70 tags deployed to track birds from Alaskan and Canadian breeding grounds, and from Texas and Louisiana wintering grounds. Work is being conducted by the Smithsonian’s Migratory Connectivity Project, USGS Alaska Science Center, Environment Canada, Texas A&M University, University of Missouri, Brighman Young University-Hawaii, and Coastal Bend Bays and Estuaries Program. The map alongside was provided by Autumn-Lynn Harrison of the Smithsonian Migratory Bird Center and shows example migration routes from one breeding population in Nome, Alaska. 

Colour-ring studies. Satellite tags are a key part of modern wader and shorebird studies, providing immediate insights from just a small number of birds, but simple bits of plastic can play a role too, especially in Western Europe, where lots of birdwatchers visit coastal sites. Colour-ring studies in East Anglia and northwest England are revealing more about how Grey Plovers use a suite of different estuaries during the course of the non-breeding seasons and will ultimately monitor annual survival rates. It will be interesting to learn whether individual birds hold territories in each of the estuaries that they visit, to moult, spend the winter and prepare for spring migration. The importance of allocating individual leg-flags to ringed birds is discussed in Bar-tailed Godwit: migration & survival.

I look forward to seeing more papers about the Grey and Black-bellied Plover, the shorebird that breeds at the top of the world.

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

@grahamfappleton

Sixty years of Wash waders

Weighing a Turnstone

The Wash Wader Ringing Group (WWRG)** started with a bang on 18 August 1959, when the team made a catch of 1,132 birds in a Wildfowl Trust rocket-net at Terrington, in Norfolk. Over the years, cannon have replaced rockets, catches have become generally smaller and the scientific priorities have been refined, but the Group continues to focus upon discovering more about the waders that use the Wash. This blog attempts to summarises what has been learnt about the waders that rely upon the Wash, the vast muddy estuary that lies between Lincolnshire and Norfolk, on the east coast of England.

** The Wash Wader Ringing Group changed its name to the Wash Wader Research Group in 2022, reflecting the broader range of studies that have evolved over the years.

Wee quiz: What’s the best match between these Wash waders and the countries that they are quite likely to have come from? Answers at the end of the blog:

• Species: Bar-tailed Godwit, Black-tailed Godwit, Curlew, Oystercatcher, Sanderling & Turnstone
• Countries: Canada, Finland, Greenland, Iceland, Norway & Russia

Sixty years ago, the first goal was to understand where the vast flocks of waders that visit the Wash came from – a task that would provide great insights into the way that the whole East Atlantic Flyway works. In this time, over 300,000 birds have been caught and ringed on the Wash, as you can see in the table below. Equally importantly, hundreds of bird-ringers from across the UK and scores of visitors from around the world have joined WWRG teams, in order to learn more about the study of shorebirds. Further international collaboration has been fostered through overseas visits by WWRG members and emigration of some key personnel. The impact of the Group is truly global, as you can read in the WWRG report for 2014/2015.

A total of 307,226 birds is impressive, especially when some of the species totals are compared to the national totals of the BTO Ringing Scheme for the whole of Britain & Ireland since 1909. WWRG is responsible for over 40% of the Grey Plover, Knot, Sanderling and Bar-tailed Godwit, with Grey Plover topping the list at nearly 60%. These are terrific achievements for a group of volunteers. I don’t have the figures but I reckon that Nigel Clark has been responsible for the largest number of catches.

Firing box connected to 4 cannon-nets

In the early days, rocket nets were borrowed from the Wildfowl Trust for an annual summer week of catches, but the development of cannon-nets gave opportunities for all-year ringing. The intensity of the Group’s activities grew in the 1970s, when there was a threat to build a freshwater reservoir on the mudflats. For a couple of years, Clive Minton (founder and leader) persuaded us to visit fortnightly, so that we could get better data on weight-gain and turn-over, using a mixture of cannon-netting and mist-netting. Everything we knew was published by the Group as The Wash Feasibility Study in 1975. These days, the Group gets together about ten times a year for catching and colour-ring-reading sessions.

By catching and ringing large numbers of the key species that visit the Wash, the Group was able to generate maps showing what are now well-known patterns of migration (see Which wader, when and why?). Early on in the Group’s history, there was a focus on nine species, with Black-tailed Godwit added as a tenth when numbers increased. Each of these species has its own section below. The maps were prepared for the Wash Wader Ringing Group 2016/2017 Report by Ryan Burrell, using data stored within the BTO archives. Blue dots represent WWRG-ringed birds that have been found abroad. Red triangles represent foreign-ringed birds caught on the Wash. The base maps used are by courtesy of Natural Earth (www.naturalearthdata.com).

Oystercatcher

The map alongside clearly demonstrates the strong link between the Wash and Norway. Other interesting things that have been discovered about Oystercatchers:

• They live a long time. An Oystercatcher that we caught at Friskney on 30 July 1976 broke the longevity record for a BTO-ringed wader when it was shot in France on 4 April 2017 (41 years 1 month and 5 days). It was ringed as an adult so we don’t know the exact age – but it must have been at least 43 years old. There’s a WaderTales blog with a list of longevity records for BTO-ringed waders.
• When life gets tough, Oystercatchers fail to complete their autumn moult, retaining some of their outer primaries for an extra year. The ability to complete moult and annual survival rates are both affected by cockle and mussel supplies on the Wash. There’s more about this in two papers in Biological Conservation and the Journal of Applied Ecology.

Grey Plover

In the early days of the WWRG, Grey Plovers occurred in much smaller numbers than they do now. Writing in an article about the first 40 years of the Group, Clive Minton told the story of the first catch of 100, made in 1963, that was celebrated with three bottles of champagne provided by the late Hugh Boyd, delivering on an incentive that he had promised.

• Over half of the Grey Plover that have been ringed in Britain & Ireland since 1909 have been ringed by WWRG since 1959 (58.9%)
• All of the Grey Plover using the Wash breed in Siberia. Some birds spend the winter on the Wash but there are autumn moulting flocks of birds that will go on to winter in other parts of Britain & Ireland, and spring and autumn passage of birds that travel as far south as West Africa.
• Grey Plover are late to leave the Wash, with the last departures not occurring until the start of June. Unsurprisingly, they are some of the last waders to return at the end of summer, which puts pressure on birds to finish moult before the short, cold days of winter. Some adults fail to complete primary moult, especially if food supplies are low. There is more about Grey Plover moult in this WaderTales blog.

Knot

First-winter Knot (subterminal bands on wing coverts and, as yet, unmoulted juvenile fethers on upper-parts)

Knot (or Red Knot) are truly international waders, as is shown in this map of movements of islandica  (and a few canutus) birds  to and from the Wash. Several WWRG members have been heavily involved in efforts to understand the decline in numbers of the rufa subspecies in Delaware Bay (on the North American eastern seaboard) and Clive Minton has been at the heart of efforts to explain the sudden drop in survival of piersmai and rogersi adults that winter in Australia and migrate to Arctic Russia via the Yellow Sea (see Wader declines in the shrinking Yellow Sea).

• We are still learning about Knot migration. The cluster of reports of WWRG-ringed birds in Northern Norway looks odd on this map projection but it turns out that this is a well-used stopping-off point for islandica Knot heading for northern Greenland and NE Canada. This route was first confirmed in 1985, when a joint Durham University and Tromsø University expedition caught 18 Wash-ringed birds in a total catch of 1703 birds.
• The dot in Siberia looks odd but isn’t. This will be a bird of the canutus race, small numbers of which pause on the Wash in autumn and spring, on their way between the Russian Arctic and west Africa.

• 

  Setting cannon-nets

  Many birdwatchers visit the Wash in autumn and winter to see the swirling Knot flocks at Snettisham and Holme. If high tide is at first light, Knot and other waders sometimes roost on Heacham Beach, giving the occasional opportunity to make a significant catch. The most recent of these, on 11 February in 2012, included 2757 Knot, 77 of which were already wearing rings.

• Knot numbers on the Wash are highest in autumn. After moulting, many birds fly west. Colour-flagging by WWRG is designed better to understand these movements.
• The most recent analysis of wader populations in Great Britain showed that there was a drop of nearly 20% in wintering Knot numbers (from 320k to 260k) in less than a decade (see Do population estimates matter?). Regular catches on the Wash will help produce estimates of annual survival rates and age ratios of the islandica subspecies.

Sanderling

The biggest catches of Sanderling are generally in the summer, when the Wash is a meeting point for birds from Greenland and Siberia. July can sometimes see catches of 200 or more birds. Traditionally, a Sanderling catch was the curtain-raiser at the start of Wash Week, an opportunity for the whole team to make one catch before splitting into ‘Terrington’ and ‘Lincolnshire’ teams for the rest of the main summer trip.

• Wintering Sanderling on the Wash are thought to be exclusively of the race that heads northwest in the spring, to Greenland via Iceland.
• Late summer and spring see the addition of birds passing through on their way from/to Siberia and extra birds from Greenlandic breeding areas.
• I well remember the first time we caught a Sanderling (on 26 July 1975) wearing an Italian ring (caught in Italy 9 May 1975). Thanks to Jeroen Reneerkens (whose work is covered in this blog) I now understand that this is probably a bird that migrates from Namibia to Greenland in spring, via the Mediterranean. It will have been on its way back to Namibia when caught in July.

Dunlin

Sam Franks, looking for the buffy tips on inner coverts, which distinguish first-year birds from adults

Nearly half of the waders caught by WWRG have been Dunlin – a total of 140,168 up until the end of 2018. There were really big flocks of Dunlin in the 1970s but numbers have dropped over the years, with peak counts now half what they were, according to WeBS data.

• We caught over 3,500 Dunlin in one week in 1976 but the annual total has exceeded 1,000 in only four of the last ten years. Partly, this reflects a change in behaviour in the summertime, with fewer waders roosting on fields and hence less catchable.
• Three races of Dunlin visit the UK. Our winter birds are alpina, from Siberia, NW Russia and northern Scandinavia. A lot of July birds are schinzii, breeding in the UK and as far north as Greenland, and we occasionally try to convince ourselves that we have caught an arctica from northern Greenland.
• Data collected for the WeBS survey suggest that national winter totals have dropped by over 40% in 25 years. This could perhaps partly be explained by a redistribution of alpina, with new generations of young birds settling in wintering areas on the other side of the North Sea. Warmer winters may well make this a more practical proposition than in the 1970s. There’s more about this in this paper.

Black-tailed Godwit

Newly ringed Black-tailed Godwit, caught in a mist-net at night.

Black-tailed Godwits became a priority species in 1995, when Jennifer Gill (University of East Anglia) started a project to study the movements of individuals, using colour-rings. Nearly 25 years later, the WWRG-ringed Black-tailed Godwits have contributed data to numerous papers, largely focusing upon migration.

• The Wash is a hugely important area for moulting islandica Black-tailed Godwits. Some birds stay in East Anglia for the winter but others move south and west within the UK, west to Ireland and south to France, Portugal and Spain.
• There are several blogs about Black-tailed Godwits in this WaderTales contents list.

Bar-tailed Godwit

One of the key things that was learned from the sudden decline in annual survival rates in a range of species that use the Yellow Sea (as mentioned above) is a need for regular monitoring of marked birds. The WWRG’s Scientific Committee set up colour-flagging projects for Bar-tailed Godwit, Curlew and Grey Plover, in order to increase the reliability of estimates of annual survival for three species that the Group does not catch in sufficient numbers to generate good retrap histories. Birdwatchers can help by reporting colour-marked birds here.

• In Bar-tailed Godwits: Migration & Survival there is a comparison of the data generated by a catch of 505 Bar-tailed Godwits in 1976 with the information that has been generated recently, using colour-flags.
• Bar-tailed Godwits are long-lived birds. A WWRG bird holds the current record for a BTO-ringed Bar-tailed Godwit: 33 years and 11 months between ringing in 1978 and recapture in 2008. BTO longevity records are discussed in this WaderTales blog.
• Colour-ring reading is now a significant element of Group activities, as described by Rob Pell in the WWRG Report for 2016/2017.

Curlew

Back in the 1970s, Curlew were still hunted on the Wash (paté made from autumn-shot birds was reported to be very tasty). Shooting stopped in Great Britain in 1981, when the maximum winter count on the Wash had dropped to about 3,000 birds, and by 2003/04 the maximum winter count was 15,336. Since then, numbers have declined, in line with national and international trends.

• A large number of Curlew on the Wash in winter are from Finland and surrounding countries. Surprisingly few are of UK origin.
• Birds wearing WWRG leg-flags have been observed breeding in the Brecks (Norfolk/Suffolk).
• The Curlew is internationally designated as ‘Near Threatened’. Is this really true when we can still see a field with 1000 roosting Curlew in Norfolk? Answers here.

Redshank

The latest population estimates suggest that Great Britain has lost 26,000 wintering Redshank in less than a decade, representing a drop of 20%. Perhaps WWRG data can be used to help to explain these declines? Here are some of the things we know:

• The Redshank on The Wash in the winter are mainly a mixture of birds from around the Wash, across the UK and from Iceland.
• In cold winters, Redshank wintering on the Wash die in large numbers. After a period of severe weather in 1991, nearly 3,000 wader corpses were collected from along the tide-line, about 50% of which were Redshank. The winter WeBS counts for Redshank dropped by 50% after this mortality event but have recovered somewhat since then.
• An analysis of nearly 1,000 dead Redshank showed that about two-thirds were of Icelandic origin. There was a tendency for smaller birds to be more susceptible to cold weather mortality than larger birds of the same species (More information in this paper by Jacquie Clark)

Turnstone

Winter Turnstone are birds that will head for Greenland and NE Canada in the spring but recoveries of birds in Finland and other Scandinavian countries indicate a passage of continental birds. African recoveries of WWRG-ringed birds probably include birds from Canada/Greenland and Finland/Scandinavia.

• Turnstone wearing US Fish & Wildlife Service rings are occasionally caught on the Wash. Some of these rings were put on by Guy Morrison and his colleagues in Alert, Ellesmere Island, Canada. Guy was an early member of WWRG. It’s a small world!
• The first Wash Turnstone were colour-ringed in 1999, as part of a study to understand why birds were feeding on the docks at Sutton Bridge. There is a WaderTales blog about the resulting paper by Jen Smart and Jennifer Gill. Colour-ringing continues, to measure annual survival rates.
• Turnstone have a reputation for eating almost anything (including dog excrement and a human corpse) so do not be surprised if you see a colour-ringed bird scavenging for chips on the Hunstanton sea-front.

A few more highlights

Ringed Plover: this is not one of the ten key study species but 1,432 have been ringed between 1959 and 2018. Some birds are local breeders that hardly move anywhere but other birds link the Wash with Greenland, northern Norway, Morocco and Senegal.

Greenshank: The Group supports a colour-ringing project that was initiated by Pete Potts, in Hampshire. More information here.

Spotted Redshank: During the period 1959 to 2018, WWRG ringed a total of 85 Spotted Redshank, representing over 20% of the total ringed in Britain and Ireland since 1909. Amazingly, sixty of these birds were ringed on the same day – 27 July 1975. There is a blog about this catch and the recent decline in the number of Spotted Redshank visiting the UK. Fewer Spotted Redshanks.

Ruff: Until its closure, WWRG members spent many a smelly night at Wisbech Sewage Farm. This was a great place to catch Ruff, Curlew Sandpipers, Green Sandpipers etc. in mist-nets. Group members wrote a paper about Ruff moult and migration.

Rares: Occasionally there are surprises! WWRG has caught one each of Stone Curlew, Pectoral Sandpiper, Broad-billed Sandpiper and Terek Sandpiper. The last bird features in this WWRG blog.

What do we know now?

Migration studies have revealed the importance of the Wash to half a million or more waders each year – birds that spend the whole winter, others that refuel in the spring and vast numbers that rely on the food supplies in the mud to provide the energy for the post-breeding moult. There’s a selection of papers that have included WWRG data here, on the Group’s web-site.

The Group still aims to maintain its general ringing programme, so that a representative sample of the key species carry rings. Colour-ringing projects aim to provide survival estimates for Curlew, Bar-tailed Godwit, Grey Plover and Turnstone, with Greenshank and Black-tailed Godwit colour-rings contributing to migration studies. Birdwatchers who visit the Wash can help by reporting colour-marked birds here, on the WWRG web-site.

WWRG data have been used to help inform decisions about the future of the Wash but the threats keep coming. Studies of migration and seasonal turn-over in numbers contributed hugely to decisions to provide national and international protection to the area and to fend off the 1970s plan to build a freshwater reservoir on the rich mudflats. The information that has been generated by many generations of volunteers over a period of sixty years has been used to manage the level of shellfish exploitation, to inform decisions about wind turbine locations and to manage activities that can cause disturbance.

The Wash Wader Ringing Group is very keen for its data to be used – and not just for impact assessment studies. Click here to learn more.

Diamond Jubilee

Phil Ireland releasing a Curlew

Over one thousand people are estimated to have contributed to sixty years of the Wash Wader Ringing Group’s activities. We have lived in barns, rolled cars, dug tens of thousands of holes, carried nets for miles, made important catches, had depressing failures, got frostbite, been threatened by surge tides and made friends for life.

In the whole of this period, there have been only two leaders of the Group – Clive Minton* (1959-1981) and Phil Ireland (1981-present). Bird ringers, wader biologists and millions of waders owe them both a huge debt of gratitude.

You can read more about the history of WWRG on the Group’s website:

• Blog (18 August 2019)
• Article on history (Ruth Walker)
• Memories (Clive Minton*)
• Memories (Daphne Watson)

*Clive Minton died in a car crash a few months after this blog was written. Friends and colleagues have shared some wonderful memories on the IWSG website.

Photo at the top of this blog is by Cathy Ryden. Many thanks to her and to other photographers.

Wee quiz:

• Bar-tailed Godwit – Russia
• Black-tailed Godwit – Iceland
• Curlew – Finland
• Oystercatcher – Norway
• Sanderling – Greenland
• Turnstone – Canada

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

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Do population estimates matter?

How many waders spend the winter in Great Britain? The answer is provided within an article in British Birds entitled Population estimates of wintering waterbirds in Great Britain. It includes all the wader species from Little Stint to Curlew that are covered by the Wetland Bird Survey  This survey is based on monthly counts that take place at about 2000 wetlands and coastal sites. The main aim is to monitor the rise and falls in numbers over time.

Please note that Northern Ireland WeBS figures are included in a separate blog covering the island of Ireland that was published in Irish Birds.

Why do we need to know the total number of birds in Great Britain?

• If we count the number of Curlew and we have a figure for the European population then we know that Great Britain is responsible for nearly 20% of Europe’s Curlew each winter, thereby strengthening the case for national conservation action;
• If we have a national figure, then we know that a flock of 2000 Black-tailed Godwit represents (as it turns out) over 5% of the British total, which is a useful criterion when assessing the conservation importance of individual sites;
• Population totals help to put annual percentage changes into context;
• And simply because people ask questions such as “how many Greenshank are there in the country during the winter?”

So, here’s the bottom line. In their 2019 review of waterbird numbers in British Birds, a team from BTO, WWT, JNCC & RSPB reveal that an estimated total of 4.9 million waders spend the winter in Great Britain. For several species, GB holds a third or more of the East Atlantic Flyway population!

Making the counts

The population estimates owe a lot to those who undertake monthly Wetland Bird Survey (WeBS) counts on estuaries, lakes and waterways, during the winter months, year in and year out. Counts from the period 2012/13 to 2016/17 are used in the population estimates that form the basis for the 2019 review. WeBS data have many other uses, as you can read here: Wetland Bird Survey: working for waders.

For species of wader that also make use of the open coast, the Non-estuarine Waterbirds Survey of 2015/16 (or NEWS III) provided additional data, updating the NEWS II figures from 2006/07.

The vast majority of our wintering Purple Sandpipers are found on open beaches and rocky shores, as well as large numbers of Turnstone, Ringed Plover and Sanderling, together with significant numbers of Oystercatcher, Curlew and Redshank. There’s more about NEWS in this slightly dated blog: NEWS and Oystercatchers for Christmas.

The last assessment of winter wader populations was made by the Avian Population Estimates Panel and published in British Birds in 2013 as Population estimates of birds in Great Britain and the United Kingdom (APEP3). In here, estimates for waders were largely based on WeBS data for the period 2004-09 and NEWS II. The new assessment is presented as Population estimates of wintering waterbirds in Great Britain and also published in British Birds. It uses WeBS information for the period 2012-17 and NEWS III data. Effectively, there is an 8-year or 9-year difference between the two sets of figures.

The biggest losers

Great Britain is extremely important in the context of the East Atlantic Flyway, as is obvious from the fact that the area holds nearly five million waders. The WeBs counts already monitor the ups and downs on an annual basis but this review provides an opportunity to turn the percentages into actual numbers. It is concerning that, over a period representing less than a decade, the average maximum winter count for six of the species that were surveyed dropped by a total of over 150,000. These big losers were Knot, Oystercatcher, Redshank, Curlew, Grey Plover and Dunlin, ordered by number of birds lost, with Knot seeing the biggest absolute decline.

In preparing the new estimates for the British Birds paper, an opportunity was taken to refine the way that populations are calculated, based on Use of environmental stratification to derive non-breeding population estimates of dispersed waterbirds in Great Britain, by Verónica Méndez et al. The new methodology explains some of the differences between percentage changes reported by WeBS and the percentage changes obtained by comparing the latest population estimates to those in APEP3.

The Knot estimate dropped from 320,000 to 260,000. This decline is bigger than might be expected from the counts that take place at sites covered by WeBS, being larger than the ten-year decline of 14% reported in the last WeBS report. Knot are mobile species within the North Sea and Atlantic Coast wintering area and it is possible that British losses may be explained, at least to some extent, by redistribution.

The drop in Oystercatcher numbers from 320,000 to 290,000 appears to be less than 10%, compared to a ten-year decline of 12% on WeBS. Improved analysis of NEWS data helped to add some more birds to the open-coast estimate so the 10% fall may underestimate the seriousness of the Oystercatcher situation. The 25-year Oystercatcher decline on WeBS is 26%, which is not surprising if you look at the changes to breeding numbers in Scotland, where most British birds are to be found. There’s more about this in: From shingle beach to roof-top.

The Redshank decline of 26,000 is higher than would be predicted from WeBS figures, suggesting a drop of over 20% since APEP3, rather than ‘just’ 15% for the ten-year WeBS figure. This is a species that also features strongly in the Non-estuarine Waterbird Survey and that might explain the difference. Wintering Redshank are mostly of British and Icelandic origin, with the Breeding Bird Survey (BBS) suggesting a ten-year decline of 24% in our British breeding birds.

The Curlew is now globally recognised as near-threatened. The latest winter estimate is 120,000, down from 140,000 in APEP3. The new total represents between 14% and 19% of the European population, which means that we have a particular responsibility for this much-loved species. Only the Netherlands holds more wintering Curlew than Great Britain. Is the Curlew really nearly-threatened? is one of several blogs about Curlew in the WaderTales catalogue at www.wadertales.wordpress/about .

It has been suggested that the long-term declines of Grey Plover and Dunlin  may be associated with short-stopping, with new generations of both species wintering closer to their eastern breeding grounds than used to be the case. WeBS results indicate a 31% drop in Grey Plover and a 42% drop in Dunlin, over the last 25 years. There was a loss of 10,000 for both species between APEP3 and the new review, representing declines of 23% and 3% respectively.

The biggest winners

There are several big winners in the period between APEP3 (2004-09) and the new review (2012-16), although, in some cases, not all is as it seems.

The Avocet has seen further dramatic gains. with the estimated wintering population rising to 8,700. The increase is not quite as big as might have been expected, based on the 43% rise seen in ten years of WeBS counts, but it is still a dramatic continuation of a 40-year trend.

The numbers of Bar-tailed Godwit and Ringed Plover are both substantially higher but at least a proportion of each of these changes is linked to the better coverage and more sophisticated sampling methods that were discussed earlier. Bar-tailed Godwit increases may also reflect redistribution around the North Sea.

One of the consequences of improved statistical techniques, as used this time around, is the apparent decline in the estimated population of Black-tailed Godwit. The new figure of 39,000 is 4,000 smaller than in APEP3, despite the fact that the WeBS graph clearly shows an increase. Interpolation using WeBs figures suggests that the earlier population estimate should have been 31,000, rather than 43,000.

Sanderling from Greenland spend the non-breeding season as far south as South Africa but  increasing numbers of birds are wintering in Great Britain and Ireland (25% increase in 8 years in GB and 13% in 5 years in Ireland). Interestingly, survival rates of English birds are just as high as those in Namibia. The losers are birds that spend the non-breeding season in equatorial Africa, as you can read here; Travel advice for Sanderling.

There are other winners too, as you can read in the paper. At the start, I posed the question “how many Greenshank are there in the country during the winter?”.  The answer is 810, representing an increase of 200 since APEP3. The vast majority of these wintering Greenshank are birds from the population that breeds in northern Scotland, as you can read in Migration of Scottish Greenshank.

Game species

The estimates for the three wintering waders that are still on the UK quarry list have not changed since APEP3 (published in 2011) as there are no new data available.

Golden Plover: The winter estimate remains as 400,000, as there has been no comprehensive, winter survey since 2006/7. Large numbers of Golden Plover arrive from Scandinavia, Europe and Iceland in the late summer, joining the British birds that choose not to migrate south or west. The GB breeding population is probably less than 50,000 pairs. Most breed in Scotland which has seen a breeding decline of 5% in the period 1995 to 2018 (BBS). Golden Plover is still ‘green listed’.

Snipe (Common): The winter estimate remains as 1,100,000 – a figure that was acknowledged in APEP3 as being less reliable than that of most species. At the same time, the GB breeding population was estimated as 76,000 pairs, indicating at least a 4:1 ratio of foreign to British birds, and that does not take account of the number of British birds that migrate south and west. Snipe are ‘amber listed’ but BBS suggests a recent increase of 26% (1995-2018). There is a WaderTales blog about  Snipe and Jack Snipe.

Woodcock: The winter estimate remains as 1,400,000 – another figure that is not considered to be particularly precise, with much variation between years. The diminishing breeding population is dwarfed by winter numbers, as you can read in this WaderTales blog, with increased attention being given to ways to afford better protection of red-listed, British-breeding birds.

Many of the Golden Plover, Snipe and Woodcock that spend winter in Great Britain are birds that breed in Fennoscandia (Finland, Sweden & Norway). The latest assessment of breeding numbers shows that populations of all three species are stable. See Fennoscandian Wader Factory.

January counts

The paper in British Birds also includes a table of January population estimates, to provide data that are comparable to mid-winter counts in other countries. These figures are used in waterbird monitoring for the International Waterbird Census for the African Eurasian Flyway. The main table (and figures mentioned above) are average maximum winter counts (in the period September to March). Black-tailed Godwit is one species that illustrates the difference, with a mean of 30,000 in January and a mean peak count of 39,000. Having moulted in Great Britain, some Black-tailed Godwits move south to France and Portugal in late autumn, returning as early as February. January counts are therefore substantially lower than early-winter and late-winter counts. There is more about the migratory strategy employed by Black-tailed Godwits that winter in southern Europe in Overtaking on Migration.

Looking forward

The authors have done a tremendous job. They have refined the way that estimates are calculated, they have combined the results from WeBS and NEWS III, and they have delivered population estimates for 25 wader species and many more other species of waterbirds. These population estimates will be used in conservation decision-making until the next set of numbers becomes available. Meanwhile, thousands of birdwatchers will count the birds on their WeBS patches in each winter month, every year. Without them, this paper could not have been written.

Before the next assessment, there will need to be another NEWS survey, to check up on species that use rocky and sandy shore birds, such as Purple Sandpipers, Turnstone and Curlew. Hopefully, there will also be a dedicated survey to assess Lapwing and Golden Plover numbers and perhaps we might find a way to refine the old estimates for Woodcock, Snipe and Jack Snipe.

Paper

Population estimates of wintering waterbirds in Great Britain. Teresa Frost, Graham Austin, Richard Hearn, Stephen McAvoy, Anna Robinson, David Stroud, Ian Woodward and Simon Wotton. Published in British Birds Volume 112. March 2019.

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

@grahamfappleton

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.

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

The 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, a few WaderTales articles that use WeBS data are highlighted below. Click on the links in bold if you want to read a particular story. Link to latest WeBS report.

Curlew counts

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.

This blog discusses how much the 1980 to 1995 recovery in winter numbers can be attributed to hunting – After the hunting stopped.

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 and Welsh Oystercatchers

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.

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

WeBS counts were used to explain what happened to the Oystercatchers that winter in South Wales when cockle numbers collapsed. One of the key messages from the study is that it is really important to protect networks of sites, to give waders alternative feeding sites when conditions change. See When Oystercatchers can’t find food.

Mid-winter movements

The 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.

Population estimates

These two blogs review the latest wader population estimates for Great Britain and the island of Ireland

National patterns and local counts

Groups 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

Every 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 was a good year for several species that breed in Iceland, particularly Black-tailed Godwits. A great summer for Iceland’s waders puts the 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

The 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 assessment of the results from NEWS-III in Waders on the Coast.

The UK Red List

The UK holds hugely important numbers of wintering waders. This is emphasised in the blog UK Waders: “Into the Red”. There will be no surprise that Curlew is on the list but would Ringed Plover be on your ‘red list’? Dunlin and Purple Sandpiper are both recent additions, on the back of the NEWS-III counts.

New and increased threats (an addition in Nov 2022)

Diseases, changes in habitat quality and pressure from developers are not new threats to the UK’s waders but, after a period of relative calm, there are several reasons to be worried.

• HPAI has decimated seabird populations and we know that waders are at risk too. WeBS counts will monitor the seriousness of outbreaks.
• Lack of investment in sewage treatment, coupled with more frequent heavy downpours, is impacting on our estuaries and beaches. Mats of algae can reduce feeding opportunities and who knows what our waders will end up eating? Low-tide counts, in particular, will be valuable when trying to detect displacements of flocks.
• Wind energy is relatively cheap and clean but turbines need to be sited sensibly. WeBS counts, Low-tide counts and tracking will help planners, government agencies and NGO’s to minimise impacts on migrating waders.
• Given the increased price of electricity, the economic viability of tidal barrage schemes has increased. Up-to-date information is going to be important, as NGOs try to minimise habitat destruction.
• Estuaries have been pretty well protected under European legislation and it is not surprising that more unscrupulous developers are seeking opportunities to grab ‘unused’ land, emboldened by freeports and under-funded country agencies. Here’s hoping that conservation values will be maintained.
• There is an increasing realisation that waders, such as Curlew, Oystercatcher and Black-tailed Godwit need feeding areas above the high-tide mark. We need to make sure that WeBS counts are covering these sites. Birdwatchers can help by counting waders on playing fields, farmland and potential development sites, and reporting them via BirdTrack.

Many more blogs to choose from

There are over 130 WaderTales blogs to choose from in this list. Five of these articles might be of particular interest to WeBS counters:

• 

  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. 
• 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. The Grey Plover is an under-studied species but we are starting to learn more about these Plovers from the north.

Thank you

I 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.

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

@grahamfappleton

The not-so-Grey Plover

The Grey Plover may be grey in the winter but in its summer plumage the American name of Black-bellied Plover is far more appropriate. Each spring, adults moult into this breeding finery but what happens to first-years, are there differences between the sexes and are Grey Plovers ‘typical’ of the wader family as a whole?

This blog is inspired by the moult chapter from Shorebirds in Action, a book by Richard Chandler, published by Whittles Publishing. The descriptor “an introduction to waders and their behaviour” gives a clue to the fact that Richard has used his excellent photographs to illustrate aspects of shorebirds’ lives, such as moult, migration, territorial behaviour and physiology. Many of the photographs in this blog have been provided by Richard.

‘Dressing for the Occasion’

Back in the ‘old days’ a group of wader ringers would huddle over the outstretched wing of a shorebird, often in the dark, by the light of a paraffin lamp, in order to try to understand the moult of individual birds. In the case of the Grey (or Black-bellied) Plover, the primary feathers sometimes revealed an interesting story of previous difficulties experienced by an individual. More of this later.

Thanks to the development of digital photography and long lenses, the study of moult is no longer restricted to ringers looking at birds in the hand. Birdwatchers can all share in the detective work and learn more about how plumages of waders change with age and season, allowing us to identify males and females and to think about the stresses that individuals face.

The moult of Grey Plovers

Most waders moult their main flight feathers in the autumn and take on summer plumage in the spring. This adult Grey Plover (below) was photographed on the Wash in Norfolk in August. It is not in full summer plumage, having started its moult before migrating from the Taymyr region of Siberia. There’s lots more about wader migration here. Two of the primaries (P1 and P2) are new, with crisp white edges to the feathers. Over the course of the next few weeks, this bird will recommence moult by dropping P3, with moult then progressing outwards through the primaries and inwards through the secondaries. The main feather tracts are labelled.

Summer plumage feathers can be seen in the scapulars and in the coverts. In some individual Grey Plovers, and in other species, there can also be summer plumage in the tertials. In this photograph, these are hidden by the large, showy scapulars. Juvenile birds of many species are often aged by looking for buffy tips on the median coverts. The inner median coverts are protected from wear by the scapulars, so this is the best place to look for hidden evidence that a bird is a youngster. This is where to find the odd buffy fringe in a young Dunlin in its first spring, for instance, when it is  about 10 months old.

For an adult wader, the post-breeding moult is complete. The photograph alongside shows an adult bird in full winter-plumage; the picture is from Norfolk (UK) but the same photograph could have been taken in South Africa, India, Australia or South America, so global is the Grey Plover’s distribution. The bird has discarded all of the breeding plumage it acquired in the spring, and the flight feathers that were a year old. All of the coverts of the wing have been moulted and have a uniform appearance, and look at the fresh-edged tertials that fold neatly over the dark (almost black) tips of the primaries.

The next photograph shows a first-winter juvenile, newly arrived from the breeding grounds. This bird is a Black-bellied Plover in Florida. Having started life as a tiny, downy chick, it will have acquired this new set of feathers before migration. The spangling of the back is diagnostic of a juvenile Grey Plover but the golden spots can confuse a novice wader-handler, who might want to turn it into one of the golden plover family. Before winter starts, new non-breeding-type body feathers moult in, so the bird loses the spangling of the upper parts and a lot of the streaking of the under-parts.

It is not thought that one-year-old Grey Plovers breed in their first summer, with most staying on their ‘wintering’ grounds for well over a year, through to the second April or May. The photograph alongside was taken in May in Norfolk; the bird may have been sharing the beach with gorgeous summer-plumage birds that were preparing to depart for Siberia. Grey (or Black-Bellied) Plovers are nearly circumpolar breeders. They are missing from Greenland and Northern Scandinavia but breed across the northern coasts of Russia, Alaska and Canada – only three countries but a vast area of tundra.

The next figure is a composite of two of the photographs, created to show the key diagnostic features of an adult and immature in winter plumage. The notches on the tertials are particularly pronounced in the young bird because the feathers were already nearly a year old at this point – it is not always this easy! When assessing the age of any wader, the tertials and coverts are key feathers to check out.

Primary exceptions

In many ways, the Grey Plover is a fairly typical medium-sized wader; adults moult their main flight feathers (wings and tail) in the autumn but juveniles have to wait until the early summer of their second year before they do the same. This first primary moult of these young birds may start as early as June and is completed in August or early September, two months ahead of breeding adults. To learn more about Grey Plover moult see this paper by Nick Branson & Clive Minton from the Wash Wader Ringing Group.

Smaller waders, such as the alpina Dunlin that spend the winter in Britain & Ireland, typically breed when only a year old. Unlike Grey Plovers, Dunlin moult into breeding plumage in their first spring. When they return from Russia in the same summer they can still be aged if there are juvenile inner median coverts with unworn buffy fringes. Primaries in these one-year-old birds tend to be more worn than those of adults, being three months older and having been used for one more migratory journey.

In some species, such as Semipalmated Sandpiper, you can find young birds in the spring with a small number of fresh outer primaries. By moulting the outer, and most worn, of their flight feathers during the wintering period they are presumably able to increase flight efficiency for the journeys north and south. Young birds of the tundrae race of the Ringed Plover take this early primary renewal strategy even further, by undergoing a complete primary moult in their first winter, while on the wintering grounds.

Under stress        

Moult is an energetically expensive activity. When resources are low, it may not be possible to complete the moult process. In this BTO report by Phil Atkinson and colleagues, about wader mortality associated with die-offs of cockles and mussels in the Wash (UK), they showed that more Oystercatchers suspend moult in years with very low food supplies. In these ‘bad shellfish years’, it was not uncommon to find Oystercatchers with one or more unmoulted outer primaries – old feathers that would be retained until the next autumn moult.

The same thing can happen in Grey Plovers but it is more likely that they will suspend moult in the autumn and then finish in March. In the Branson & Minton paper mentioned above, it was estimated that 30% of adults suspended moult for the harsh winter months. The paper was written in 1976 and it would be interesting to know whether the proportion of birds suspending has dropped, given that winter weather now tends to be less severe.

Suspended moult is found in Grey and Black-bellied Plovers across the world. The photograph alongside was taken in Florida on 20 December. The unmoulted outer primary is more pointed and browner than the other nine.

Gender

The gender of winter-plumage Grey Plovers cannot be determined, even in the hand, but the summer plumage is pretty diagnostic. A bird with a jet-black belly, with perhaps the odd white tip to a feather, and an almost pure white band behind the black face and neck is probably a male (as here). If the bird is less well-marked – brownish-black on the front with more mottling – then you are likely to be looking at a breeding plumage female. Come the autumn, all of this finery will disappear and the Black-bellied Plover will become a Grey Plover once more.

Moult in other species

This blog focuses on the moult of one species. If you want to learn more about moult in general and many other aspects of the behaviour of waders then immerse yourself in Shorebirds in Action, An Introduction to Waders and their Behaviour by Richard Chandler. Click here for link. 

Moult features strongly in this WaderTales blog about Black-tailed Godwits and in this blog about Lapwings.

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

@grahamfappleton