UK waders: “Into the Red”

If you ask British birdwatchers to name the eleven wader species that are causing the most conservation concern in the UK, they would probably not include Dunlin. Curlew may well be top of their lists, even though the most recent population estimate is 58,500 breeding pairs, but would people remember to include Ruff?

This blog is a new incarnation of Nine Red-listed UK Waders, explaining why there are now eleven shorebird species on the UK Red List. Its publication coincides with the appearance of the BTO book Into the Red which highlights the problems being faced by seventy species that breed and/or spend the winter in the United Kingdom. The work of seventy writers and seventy artists has been curated by Kit Jewitt (@YOLOBirder on Twitter) and Mike Toms (BTO), and the book is being sold to support the work of both the BTO and the Rare Breeding Birds Panel.

What’s a Red List?

The UK Red List is made up of a strange mixture of common and rare species. Nobody will be surprised to see fast-disappearing Turtle Dove and Willow Tit, but why are 5.3 million pairs of House Sparrow (right) in the same company?

The list is very important because it helps to set the agenda for conservation action, influences the way that money for research is distributed and focuses attention during planning decisions. The main criteria for inclusion are population size – hence the inclusion of species that are just hanging on in the UK, such as Turtle Dove – and the speed of decline of common species. Data collected by volunteers, working under the auspices of the British Trust for Ornithology (BTO), measured a population decline for House Sparrow of 69% between 1977 and 2018, which is worrying enough to earn this third most numerous breeding species in the UK a place in Into the Red.

Mark Eaton of the Rare Breeding Birds Panel explains how listing works.

The Birds of Conservation Concern (BOCC) system, through which the Red List and Amber Lists are determined, uses a strict set of quantitative criteria to examine the status of all of the UK’s ‘regularly’ occurring species (scarce migrants and vagrants aren’t considered), and uses a simple traffic light system to classify them. There are ‘Red’ criteria with thresholds for rates of decline in numbers and range, historical decline and international threat (if a species is considered globally threatened it is automatically Red-listed in the UK), together with a range of other considerations such as rarity, the international importance of UK populations, and how localised a species is. If a species meets any of the Red List criteria it goes onto the Red List.

This blog is about the eleven waders in Into the Red, but there are 59 other fascinating species accounts and wonderful artworks. Each of the species accounts below starts with a quote from the book and is accompanied by a low-resolution version of the artwork.

Dotterel

“Dot, dot, dot, Dotterel. Disappearing – a dash, dashing off the page.” – Alicia Hayden

The UK’s small population of Dotterel is restricted to the high tops of Scottish mountains, with only occasional breeding reports elsewhere. Three decades ago, the warning bells were raised, as warming conditions and an elevated snowline turned the Dotterel into a poster bird for climate change campaigners. The detailed reasons for the species’ decline may still need to be nailed down but candidate causes, such as declining insect food supplies and the increasing numbers of generalist predators, are probably all linked to a changing climate – squeezing Dotterel into a smaller area of the mountain plateaux of Scotland.

There’s a blog about the decline in Dotterel numbers called UK Dotterel numbers have fallen by 57%, based upon a paper that uses data up until 2011. At this point, the population was estimated at between 280 and 645 pairs. There has been no suggestion of improvement since that blog was written. Interestingly, Dotterel may have a way out of their predicament, as we know that marked individuals move between Scotland and Norway in the same breeding season. See also Scotland’s Dotterel: still hanging on, which highlights the pressures that youngsters face in North Africa, during the first eighteen months of their lives.

Ringed Plover

“The gentle scuttle over the rocks, the unmistakable bum-bob and the elegant glide into a nest site– Dan Rouse

One of the criteria that the BOCC panel takes into account, when constructing the Red List, is the responsibility the UK has for a species or subspecies in the breeding season, during winter or both. The Ringed Plovers we see in the UK in the winter are almost exclusively of the hiaticula subspecies; birds that breed in southern Scandinavia, around the Baltic, in western Europe and in the UK. There are only estimated to be 73,000 individuals in this subspecies, so the 42,500 that winter in the UK constitute a large percentage of the Ringed Plovers that breed in many of these countries.

The Wetland Bird Survey graph shows a decline of over 50% between 1989 and 2014. At the start of the period, Ringed Plover numbers were at an all-time high but this is still a dramatic and consistent drop. Numbers on the open coast did not drop as much (see Waders on the coast) and those on estuaries may have stabilised or even have increased slightly, since 2014, but Ringed Plovers need some good breeding years. Disturbance is an issue for nesting Ringed Plovers, which share their beaches with visitors and dogs, as discussed in this blog about the ‘no go’ areas along the Norfolk and Suffolk coasts – On the beach. Winter disturbance can be a problem for waders too (see Disturbed Turnstones).

Lapwing

“I heard them before I saw them. Like the plaintive squeak of a rubber toy, or an oboist tuning up …” – Tessa Boase

The Lapwing used to nest across the whole of the United Kingdom and was a common bird in almost every village. It’s still the most numerous breeding wader in the UK, with 97,500 pairs (APEP4), beating Oystercatcher by just 2,000 pairs. Numbers dropped by 55% between 1967 and 2018, according to BirdTrends 2020, published by BTO & JNCC. Huge losses had already occurred over the previous two centuries, as land was drained and vast numbers of eggs were collected for the table. The Lapwing is now a bird associated with lowland wet grasslands and the uplands, rather than general farmland.

Red-listing has been important for Lapwing, increasing the profile of the species and encouraging the development of specific agri-environment schemes targeted at species recovery. These include ‘Lapwing plots’ in arable fields and funding to raise the summer water tables in lowland grassland. Several WaderTales blogs describe efforts to try to increase the number of breeding waders in wet grassland, especially Toolkit for Wader Conservation. The loss of waders, and Lapwings in particular, from general farmland is exemplified in 25 years of wader declines. There are many predators that line up to take Lapwing eggs so it pays to nest in loose ‘colonies’, so that guard duties can be shared.

Whimbrel

“Whimbrel have been doing this journey, between tundra and heath of northern Europe to mudflats and mangroves of Africa, for at least 1.9 million years – Rosie Ellis

Most British and Irish birdwatchers think of Whimbrel as spring migrants, enjoying seeing flocks of Icelandic birds when they pause on their way north from West Africa (see Iceland to Africa non-stop). There is a small, vulnerable UK population nesting almost exclusively on Shetland. The latest estimate is 290 pairs (2009), down from an estimate of 530 pairs, published in 1997. We await the results of a 2021 survey with interest. Many pairs have been lost from Unst and Fetlar and this blog about habitat requirements might give clues as to why: Establishing breeding requirements of Whimbrel.

The curlew family is in trouble across the Globe, potentially because these big birds need so much space (see Why are we losing our large waders?). Hints of future issues for Eurasian Whimbrel are coming from Iceland, where forestry is squeezing them out of some key areas: Iceland’s waders need a strategic forestry plan.

Curlew

“A song that seems to split in mid-air and take the heart in two directions at once – David Gray

What more can be said about Curlew, ‘promoted’ to the red list in 2015 and designated as ‘near threatened’ globally. Most significant is the story from Ireland, where 94% of breeding birds disappeared in just 30 years. These blogs provide more information about the decline and review some of the reasons.

Across every part of the UK, stakeholder groups have come together to support populations of breeding Curlew, using a mixture of habitat management, predator reduction and nest protection measures. One recent innovation is to raise chicks in captivity, in an attempt to boost local populations in England. There’s more in Will head-starting work for Curlew?

Black-tailed Godwit

“These birds become old friends and open our eyes to the world of migration – Jennifer Gill

Winter Black-tailed Godwit numbers are booming but these are islandica – birds that have benefited from warmer spring and summer conditions in Iceland, as you can read here in: From local warming to range expansion. Their limosa cousins are in trouble in their Dutch heartlands (with declines of 75%) and there have been similar pressures on the tiny remaining breeding populations in the Ouse and Nene Washes, as you can discover in England’s Black-tailed Godwits. A head-starting project in the Washes is boosting the number of chicks; so much so that released birds now make up more than a quarter of this fragile population. Red-listing has shone a spotlight on this threatened subspecies, attracting the funding needed for intensive conservation action.

Ruff

“But then, good grief, in May and June, I’m treated to a different plume; A glorious crown, I gush and swoon – and then, no doubt, I change my tune. – Jess French

Some Ruff spend the winter months in the UK and numbers are boosted in spring as birds pass through on their way from Africa to Scandinavia and the Baltic countries. Occasionally, males in glorious breeding attire will display in leks, perhaps attracting the attention of females. As a (very) scarce breeder, Ruff automatically earns a place on the Red List.

250 years ago, Ruff were breeding between Northumberland and Essex, before our ancestors learnt how to drain wetlands and define a hard border between the North Sea and farmland. Hat-makers, taxidermists and egg-collectors added to the species’ woes and, by 1900, breeding had ceased. The 1960s saw a recolonisation and breeding Ruff are still hanging on. Lekking males cause excitement in sites as disparate as Lancashire, Cambridgeshire and Orkney, and there are occasional nesting attempts. Habitat developments designed to help other wader species may support Ruff but the situation in The Netherlands does not suggest much of a future. Here, a once-common breeding species has declined to an estimated population of 15 to 30 pairs (Meadow birds in The Netherlands).

Dunlin

“Memories of sunny days, swirling flocks of waders and blisters from closing metal rings still linger. How can a bird that was so numerous less than 50 years ago now be Red-listed?” – Graham Appleton

There are good reasons for the addition of Dunlin to the UK Red List; breeding numbers of the schinzii race have declined significantly and the number of wintering alpina Dunlin in Great Britain dropped 10,000 between two periods that were only eight years apart, as you can read in this blog about population estimates for waders.

The fall in breeding numbers is probably the bigger problem, as indicated by range reductions in successive breeding atlas periods (1968-72, 1988-91 and 2008-11). It’s hard to monitor what is happening to numbers on a year-by-year basis because the breeding distribution is too patchy and thin to be picked up via the Breeding Bird Survey. Alarm bells are being raised in Ireland, where numbers have dropped to between 20 and 50 pairs (Status of Rare Breeding Birds across the island of Ireland, 2013-2018), and in the Baltic, where numbers have fallen by 80% since the 1980s. There’s a WaderTales blog about Finnish Dunlin.

The winter decline in the UK may or not be an issue, although it has to be considered as part of large-scale moderate losses across the whole of western Europe. There is a theory that, over the years, as winter conditions on the continental side of the North Sea have become less harsh, new generations of juvenile alpina have settled in countries such as the Netherlands, instead of continuing their southwesterly migrations from northern Russia. Once a wintering site has been chosen, individuals are site faithful, so one ends up with newer generations on the continent and ageing adults in the UK and Ireland. WeBS counts for Dunlin are half what they were 25 years ago.

Purple Sandpiper

“It’s an easy species to overlook, the Purple Sandpiper. For a start, they’re not purple” – Mark Eaton

Purple Sandpiper earns its red listing because a very small number of pairs nest in Scotland. Proof of successful breeding is rare and the species may drop off the list at the next review, as Temminck’s Stint did in 2015. Extirpated species (birds that no longer breed) are not red-listed.

In winter, the rocky coasts of the UK are home to Purple Sandpipers from the Arctic, with a suggestion that North Sea coasts, south of Aberdeen, mainly play host to birds from Spitsbergen and northern Scandinavia, with Greenlandic and Canadian birds more likely to be found further north and on the Atlantic coast. Coastal numbers declined by 19% between 1997/98 and 2015/16, according to the Non-estuarine Waterbird Survey, and WeBS counts suggest numbers have at least halved over a period of 25 years. The Highland Ringing Group has shown that the number of young Purple Sandpipers has been declining on the Moray Firth, suggesting several years with relatively poor breeding success, for birds migrating from the northwest, or short-stopping by new generations of youngsters, as discussed for Dunlin. Perhaps they are wintering in Iceland these days?

Woodcock

“Like clockwork, I’d encounter this sight at 7 pm each summer evening as one flew over my head in the back garden, heading towards the thick woodland. – Megan McCubbin

The presence of Woodcock on the Red List causes heated debate; how can this still be a game species? Red-listing is indisputable; the most recent survey by BTO & GWCT showed that there was a decline in roding males from 78,000 in 2003 to 55,000 in 2013, with the species being lost from yet more areas of the UK. Each autumn, the number of Woodcock in the UK rises massively, with an influx of up to 1.4 million birds. Annual numbers depend upon seasonal productivity and conditions on the other side of the North Sea. A recent report on breeding wader numbers in Norway, Sweden and Finland, shows that breeding populations of Woodcock in this area are not declining (Fennoscandian wader factory).

The UK’s breeding Woodcock population is under severe threat from things such as increased deer browsing and drier ground conditions but winter numbers appear to be stable. The difference in conservation status between breeding and wintering populations is reflected in the fact that Woodcock is on both the Red List and the Quarry List, for now. There is a WaderTales blog (Conserving British-breeding Woodcock) that discusses ways to minimizes hunting effects on British birds. These guidelines from GWCT emphasise the importance of reducing pressures on British birds.

Red-necked Phalarope

“The evening light was beautiful, and it was just amazing to watch it spinning around in characteristic fashion” – Dawn Balmer

Red-necked Phalaropes that breed in Shetland and a few other parts of northern Scotland appear to be an overflow from the Icelandic population; birds which migrate southwest to North America and on to the Pacific coastal waters of South America. This BOU blog describes the first track revealed using a geolocator.

The Red-necked Phalarope was never a common breeder and came under pressure from egg-collectors in the 19th Century. Numbers are thought to have recovered to reach about 100 pairs in Britain & Ireland by 1920. Numbers then fell to about 20 pairs by 1990, so the latest estimate of 108 pairs in 2018 reflects conservation success (The Rare Breeding Birds Panel). Given the restricted breeding range and historical declines, it is unlikely that the next review will change the conservation status from Red to Amber, despite the recovery of numbers.

In conclusion

The Red List creates some strange bedfellows. In the book, Turtle Dove follows Herring Gull (right); a bird with links to love and romance and another with at best the charm of a roguish pirate. But the List works; it creates an evidence-base that help those who devise agricultural subsidy systems, advise on planning applications, license bird control and prioritise conservation initiatives.

Into the Red aims to raise awareness of the UK’s most at-risk bird species, eleven of which are waders, and to raise money to support the Rare Breeding Birds Panel and BTO research scientists. This is a follow-up to Red67, published in 2019 and based on the Red List from 2015. It is sad that this version covers 70 species, rather than 67. Worryingly, the first Red List, produced in 1990, only had 36 species on it.

Into the Red is a lovely book that captures the thoughts and images of a generation. Details of how you can order a copy from the BTO can be found here.


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.

Will head-starting work for Curlew?

83 captive-reared Curlew were released successfully in 2019, over 130 in 2021 and a similar number in 2022 but this does not mean that head-starting is a solution to England’s Curlew problems. We don’t yet know the proportion of youngsters that survive the difficult ‘teenage years’, how many will find suitable breeding habitat and whether these birds can reliably raise chicks of their own. What have birds such as 7K, pictured here, revealed and what might happen next?

Exciting news

There has been some great TV and press coverage of head-started Curlew this summer (2022), with films of captive-reared birds being released from pens and flying for the first time. But what does the future hold for naïve birds that take to the air in Shropshire & Powys, the Severn & Avon Valleys of western England, Cornwall, Sussex and Norfolk? The first signs are good, as illustrated below in maps published by the BTO for the birds that they are tracking in Norfolk.

Satellite-tagged birds released at Ken Hill (Black stars – close to the Norfolk coast) can be seen flipping backwards and forwards between the mudflats and their release site, before beginning to explore more of the Wash estuary.

Birds released further inland, on The Sandringham Estate (White stars), started foraging in grassland areas and it took a while until any of these birds discover the coast. One bird “7Y” moved onto a little-used airfield (below), where it was seen with a flock of adults. It appears to have adopted a mudflat/grassland tidal routine, involving ‘commutes’ of ten miles each way, possibly having been guided by the adults (top row, third from the left).

One of the Sandingrham youngsters joined up with a flock of adults on an airfield five miles from the release site

It is easy to get ‘wowed’ by the TV reports and the individual stories of tracked birds but these are early days for Curlew head-starting. There’s a lot still to learn!

Why head-start Curlew chicks?

This Curlew is nearly ready to fledge

The Eurasian Curlew is in trouble, as you can read in the WaderTales blog “Is the Curlew really near-threatened?”. Annual survival rates of adults are high but productivity is low, with an estimate of 10,000 too few youngsters being fledged each year, to maintain population levels in the UK. The Irish Curlew population has crashed, providing dire warnings of what may happen soon in Wales, where there has been a decline of 73% since 1995 (Breeding Bird Survey). In southern England, most of the losses happened before 1995 and only a few populations remain, hanging on in areas such as Breckland in East Anglia.

Lessons from Black-tailed Godwits

We know that head-starting works well for limosa Black-tailed Godwits breeding in East Anglia but there was no guarantee that this would be the case when the WaderTales blog Special Black-tailed Godwits was published in 2017, to coincide with the departure of captive-reared birds from their WWT Welney release site. When the first birds not only returned in 2018 but actually raised their first chicks (see Head-starting Success), the approach looked to be successful. Over the following years, with more releases, the godwit population in the Ouse and Nene Washes has increased significantly. This temporary relief package for a beleaguered population has worked well, providing time to try to improve breeding conditions in the wild, so that Black-tailed Godwits can look after themselves. Head-starting is an intervention of last resort and cannot be a long-term solution to the problems faced by the species.

Young Curlew is now identified as 2X

It is possible to support local populations of scarce birds, such as Bitterns and Little Terns, with interventions such as increasing areas of suitable habitat and protecting nest sites, but doing the same for Curlew will be more of a problem. Here, the challenge is to halt a decline of a species that breeds across wide areas of the UK, mostly on farmed land that is not being managed for conservation. Intensive, local action is not going to be enough. This is going to need teamwork between landowners, conservation organisations and volunteers – acting at a scale that has not been tried previously. Perhaps head-starting will help?

A pragmatic plan

The most recent UK population assessment of Curlew, in British Birds, suggested that there were 58,500 breeding pairs in 2016. Numbers have almost certainly dropped since then but the species is nowhere near as threatened as England’s breeding Black-tailed Godwits. The biggest Curlew head-starting programme, led and funded by Natural England, was a response to an opportunity to use unwanted Curlew eggs – not a ‘last-chance’ solution, as it had been for Black-tailed Godwits. Each year, Curlew eggs were being collected on RAF airfields, under licence, to deter adults and reduce airstrike risk. Thanks in no small part to Natural England’s Graham Irving, many of these eggs are now being head-started, instead of destroyed.

What happens to head-started birds?

Curlew eggs in an incubator

The Natural England project builds upon the experiences of the Curlew Country team, working in the Shropshire hills and Powys borders. They released 6 head-started Curlew in 2017, 21 in 2018, 33 in 2019 and 34 in 2021. Raising extra chicks is part of an initiative that involves a broad range of stakeholders. See their website for more information.

The first stage of the head-starting process works well. Aviculturalists can rear and release chicks, with very high rates of success. They are learning more and more about the best diets, appropriate husbandry and the release process. Individual chicks wear small colour-rings, so that progress can be monitored daily, and they receive leg-flags and get weighed and measured before release. For instance, the young Curlew 7K featured above is a GPS tagged male that weighed in at a respectable 550 grammes when it was transferred to its release site on The Sandringham Estate, on 14 July 2022. By the end of August, it had moved to the Wash Estuary, as you can see in the figure above (top left map).

Before transfer to The Sandringham Estate release site, a young Curlew is checked over by a vet

From the start, the Natural England project has been built on partnerships. In the first year (2019), eggs were hatched and chicks were reared at WWT Slimbridge. Fifty young Curlew were released near-by and the first of these birds (wearing ring number 23) was found nesting near Gloucester in 2021, raising one chick of his own. In 2022, three years after release, five of the head-started Curlew were on breeding sites in the Severn and Avon area and one bird had moved to the Thames Vale. Male “23” shows that head-starting can add more Curlews to the breeding population but is he exceptional? What proportion of released birds make it this far and go on to raise chicks? The video by Kane Brides in this WWT blog tells the West Country story so far.

After a Covid-caused hiatus in 2020, the head-starting project expanded in 2021, with birds reared at both WWT Slimbridge in Gloucestershire and Pensthorpe in Norfolk. Richard Saunders, the Senior Ornithologist for Natural England, recognised the importance of learning what happens to newly-released fledglings and of monitoring potential recruitment. Working with Sam Franks of BTO and with lots of support from others, the Pensthorpe-reared Curlews are starting to reveal some of their secrets.

Where will the Pensthorpe birds set up home?

Most waders are philopatric; when they look for breeding sites, they tend to return to places close to the places in which they were raised. The release sites in North Norfolk were chosen not only because they provided suitable conditions for growing teenage waders, with low predator numbers and adults feeding nearby, but also because they are relatively close to current breeding sites, such as Roydon Common and the heaths of Breckland (see Curlews and foxes in East Anglia). There are also airfields, of course, and it will be unfortunate if birds choose these sites, given that eggs were removed to try to reduce bird-strike risk.

Radio tag (left) will drop off when juvenile feathers are replaced. Satellite tag is mounted on a temporary harness and worn like a rucsac.

All of the chicks are colour-ringed, some of them are radio-tagged and others are GPS-tagged, prior to release. By following tagged birds, as they explore the area around the release sites, the project aims to understand more about habitat use and to see if these naïve birds seem unduly prone to predation, given that they have not been trained to look out for danger by watchful parents. GPS tagging helps to paint the bigger picture; would birds move to the mudflats of the Wash and spend the whole winter in Norfolk or would some move on, to southern England, Ireland or France, for instance? These data will hopefully be augmented by reports of colour-ringed birds that do not carry tags.

2C takes to the air after release at Ken Hill

The first results have been encouraging. For example, a GPS tagged female from the first cohort released in Norfolk in 2021, wearing flag 0E, has followed the ‘stay local’ option. She spent the winter on the saltmarshes of RSPB Frampton, on the Wash in Lincolnshire, and has largely stayed on the south shore of the Wash through her first summer, showing no evidence of visiting any type of breeding habitat yet. A male Curlew wearing flag 4P has been more adventurous, spending the winter on the Exe Estuary in Devon, a site used by some adult Curlews that breed in Eastern England.

The amazing left-hand map below shows the route taken by ‘6Y’, one of the first batch of 2022 birds to be released on The Sandringham Estate. The story of this bird is told by the BTO’s Dr Sam Franks:

“The first of this year’s birds to migrate away from Norfolk departed at sunset last Wednesday & arrived on a Staffordshire field at sunrise on Thursday. It then flew towards Ireland & made an anxiety-inducing trip out into the Atlantic before returning to dry land.”

The right-hand map shows an overnight flight by ‘9L’, one of the last birds to be released from Ken Hill. This bird, pictured to the right , set off on the evening of 16th September, flew southwest overnight and headed south when it ran out of land. It landed in France at 01.30 on 17th. Although there is supposed to be a Curlew hunting ban in France (see this blog), three satellite-tagged birds from elsewhere in Europe were shot in the first weekend of the 2022 autumn hunting season. Will 9L survive the winter?

Data generated by colour-ring sightings will be analysed to check whether annual survival of youngsters in their first couple of years are consistent with figures for wild-reared chicks. This follow-up work is really important – the head-starting operation may seem to be successful but if few chicks survive long enough to breed then alternative approaches may be needed. Sightings of colour-ringed birds provide important information to add to data collected from tagged birds, which means that there is a vital role to be played by birdwatchers.

Around England

People care deeply about Curlew, as Mary Colwell explored in a recent book, reviewed in the WaderTales blog Curlew Moon, so it is not surprising that landowners feel inspired to help the species, by releasing birds on their own land. An attempt is being made to boost a tiny population on Duchy of Cornwall land on Dartmoor, using eggs from East Anglian airfields that were hatched at Slimbridge, and a licence has been granted to take eggs from a site in Northern England to be reared in Sussex, on an estate that appears suitable but where Curlew do not currently breed.

Release sites for these translocated birds do not hold many (or even any) Curlew so it will be interesting to learn whether the behaviour patterns of these fledglings are different to those of birds released in Norfolk and in the Severn and Avon Valleys of western England. All birds are being ringed, by WWT, GWCT and BTO ringers, with every report of a marked bird adding to our understanding of the success of the various projects. In each case, hopefully there will be enough money to deploy dedicated fieldworkers to monitor what happens to the released birds during the crucial first few weeks of independence, so that fledging rates can be accurately assessed, and to monitor return rates in subsequent breeding seasons. For slow-maturing birds, this follow-up work will involve a five-year commitment.

Maximising effectiveness

The work being funded by Natural England in East Anglia is expensive. It will be judged as successful if released birds augment local populations, whether these be in East Anglia (as hoped) or in another part of lowland England. If birds choose to breed in the North of England, where numbers are still high, or even overseas, then that may make it difficult to justify the expense of further rearing and monitoring work.

There is a concern that head-starting will be seen as a solution to the problems being faced by Curlew. It isn’t! The estimated shortfall in fledged chicks is 10,000 birds per year, across the whole of the UK, and head-starting will never make a big impact on that number. It may be a way to boost numbers in lowland areas, from which the species would otherwise be lost, but only if the conditions for successful breeding can be created and maintained. This means tackling the thorny problems of habitat degradation and predator numbers. Head-starting may seem like a dynamic intervention but if birds are released into areas where breeding success is too low then it’s not going to produce a sustainable solution to the problems being faced by England’s Curlew.

Photos of ringed birds are particularly appreciated

The Norfolk head-starting project would appear to tick all the right boxes – release sites with low predator numbers, right next to an estuary with lots of Curlew and with successful breeding sites near-by. Head-started birds soon start to explore the mixture of arable and tidal resources available to them and it looks as if early-years survival rates might be as high as expected of wild-reared birds. Despite all these positive signs, it will be a couple of years until this year’s young Curlew start breeding – somewhere – and that will be the crucial test of head-starting. Meanwhile, it is hoped that birdwatchers will look out for colour-ringed birds, so that survival rates can continue to be monitored. Every Curlew counts!

Norfolk-ringed head-started Curlew wear yellow flags, each with number & letter, immediately above an orange ring. Please report sightings of colour-ringed head-started Curlew using THIS LINK.


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.

A Norfolk Curlew’s summer

This blog follows the fortunes of one Curlew (B/OW-OY) as he attempts to raise chicks in Norfolk, migrates to Portugal, diverts to avoid a forest fire and returns to his winter home in a Portuguese estuary. Using tagging data we know that he left his Norfolk breeding territory in England on 17 June 2022 and arrived at Montijo, in the Tagus Estuary of Portugal, on 16 July – but that’s only part of his story.

Curlew migration

B/OW-OY (named ‘Bowie’ in a BTO press release) may have been travelling between Norfolk and Portugal for a decade or more, flying backwards and forwards between the dry grassland of inland East Anglia and the coastal mud of the Tagus Estuary. We have new insights into his life because he was ringed and tagged on 2 April 2022, as part of a project to understand Curlew breeding success rates in East Anglia – about which more later!

Curlew migration is complex. The birds that we see in autumn and winter in the UK include some local birds but the majority will have crossed the North Sea, particularly from Finland. The map alongside is taken from the BTO website. As you can see, some British-bred Curlew migrate south for the winter. At the Europe-wide scale, the major axis of migration is also from northeast to southwest, as you can discover using the European African Bird Migration Atlas mapping tool. ‘Bowie’ may be feeding in Portugal alongside birds that have bred in Poland, Finland and France.

Breckland Curlews migrate in all directions in the autumn. At least three have been found wintering on the Norfolk coast, five colour-ringed birds have travelled to southwest England (Dorset, Devon and the Severn Estuary), another of the tagged birds has flown to Ireland and a colour-ringed bird has been seen in northern Spain.

Breckland Curlew

Harry Ewing is studying Curlew in Breckland – the tapestry of heath, grassland, forestry, arable farming and military bases in the dry, heart of East Anglia. His PhD at the University of East Anglia is being undertaken in partnership with BTO and with input from RSPB. Harry is working across a range of habitats that are used by nesting Curlew, from airfields to sugar beet fields. The breeding site of B/OW-OY is a grassland heath that is managed in ways that maintain habitats that are suitable for scarce plants, invertebrates and birds. Here, pairs of Curlew breed alongside Stone-curlews and Woodlarks.

Most of Harry’s Curlew struggle to fledge any chicks, as is the case in many places across Britain and Ireland, and it will be interesting to see the papers that come out of his PhD, in due course. Two previous WaderTales blogs describe the predation problems Curlews face in East Anglia (Curlews and foxes in East Anglia) and give information about conservation interventions that suit breeding waders (Grassland management for Stone-curlew).

Catching Curlew

During his PhD, Harry has found up to 70 Curlew nests in a single breeding season and followed their outcomes until the eggs or chicks were predated or through to fledging. Harry checks on his breeding Curlew on an almost daily basis but does not always see adults on territory. By catching birds at roost, at the start of spring, and deploying a small number of GPS tags, funded from the BTO Curlew Appeal and by Natural England, he hoped to learn more about how birds use surrounding habitats and to get more accurate information about the timing of breeding events. The extra data about migration that he gets from birds like B/OW-OY are a bonus.

Harry had been looking for opportunities to catch Curlew in the Brecks when they returned to the areas in the spring. A flock of roosting birds was spotted by local graziers on 31 March 2022 and, with the help of the Breckland Farmers Wildlife Network, Nigel Clark and the Wash Wader Research Group, a catch was made on the evening of 2 April. Eleven birds were caught, all of which were colour-ringed and eight of which were also fitted with GPS tags by Sam Franks of BTO (see picture).

A ‘miracle chick’

Harry spotted B/OW-OY on the day after capture, on a grass heath just 3.7 km away from the ringing site. As luck would have it, he was paired with B/OW-OL, a newly colour-ringed female. Harry could not download data from the tagged bird, due to a lack of signal coverage, but he saw OY and OL almost daily over the next two months. Information collected on OY’s tag and sent from Portugal in July filled in some of the gaps. OY fed mostly on cultivated plots (as described in Grassland management for Stone-curlew) but he also used nearby arable farmland, especially an asparagus field about 3 km from the heath, and made a brief trip to a local airfield during the pre-breeding period.

Both OY and OW were observed regularly and Harry found their nest and a completed clutch on 6 May. As can be seen in the photograph, it was in a very open site, on dry, grazed grass heathland. When Harry checked the nest on 25 May, three chicks had hatched and one was still hatching. A second check the next day, to confirm successful hatching of the final chick, revealed a sad tableau of overnight predation: one chick was dead, one was injured and two were missing. Injuries suggested a mustelid attack – probably a stoat (see photograph above). That was the end of the breeding attempt – or was it?

Another day later, on 27 May, Harry discovered a bird he named ‘miracle chick’; a one-day-old youngster that was feeding near the nest site, on its own, with no parents guarding it. OY and OL were still present on the heath but had joined a flock of failed breeders, presumably having assumed that their chicks had all perished. Two days later, ‘miracle chick’ had moved 100 metres and latched onto a family of two 25-day-old chicks, feeding with them and sharing the protection afforded by their parents. OY and OL were still in the post-breeding flock, presumably unaware that their breeding season had not been a total failure.

Curlews gather in small flocks when they lose their chicks or nests. For them the season is over.

As Harry continued his daily checks of broods around the Brecks, to try to understand more about the predation of chicks, he was able to establish that the first step-sibling of ‘miracle chick’ was predated on the night of 31 May/1 June and the second on the next night. Nocturnal predation of big chicks is probably by foxes. ‘Miracle chick’ continued to be defended by its step-parents until 16 June. On 17 June, Harry found an adult female with a broken wing and the chick was never seen again. Perhaps she was the step-mum and the injury was sustained in unsuccessful defence of ‘miracle chick’. ,We shall never know. By this time, OL and OY appeared to have left the heath; the last sighting of the female was on 10 June and the tagged male was not spotted after 16 June.

Heading south

Thanks to the information that was transmitted from Portugal, we know that B/OW-OY (Bowie) left Breckland at 21.30 (UTC) on 17 June, arriving on the Essex coast at Brightlingsea just 80 minutes (and about 50 miles) later. He spent the next four weeks feeding around the coast of Mersea Island, leaving at 20.00 on 14 July. There was a nine-hour lay-over in Spain on 15 July, before another evening departure (20.40). The last part of the journey is interesting; it included what looks like a diversion around the forest fires that were burning in the Ourém region in Portugal at that time (see map).

It is fascinating to think about how this one Curlew from Norfolk might have travelled to Portugal. Did it fly to the coast alone? Did it meet up with other birds that were heading south from Essex and fly in a flock? Did it ‘change flocks’ in Spain, as we would planes at an airport? This blog, based on a recent French paper, gives a feeling of what it is like to be a migrating Curlew: The flock now departing.

Threatened winter home

Bowie arrived on the Tagus Estuary at 09.30 on 16 July and he may well stay here until next February or even March. The Montijo peninsula, which appears to be his winter home, is one of the most important parts of the Tagus Estuary for Curlew. They feed in the mud and roost on salting islands, following the rhythm of the tides. This estuary is right next to Montijo Air Force Base.

The saltmarsh at Montijo on 18 July 2022. Josh Nightingale counted 22 Curlew.

Montijo Curlew are accustomed to the relatively infrequent take-offs and landings by military aircraft, in the same way that Curlew on RAF bases in East Anglia are happy to breed on the grassland alongside runways. All this will change, however, if the plan to expand the site, lengthen the runways and introduce all-day flights of passenger aircraft goes ahead (planned to operate at 5 minute intervals). Add on control measures to reduce the potential of bird-strikes to aircraft and Montijo and the Tagus as a whole will become much less attractive to hundreds of thousands of waterbirds. As you can read in Tagus Estuary: for birds or planes, we need to fight very hard to stop this new airport which is on a specially protected Ramsar site. If this jewel on the East Atlantic Flyway can be degraded then what is there to stop similar developments elsewhere?

One tagged bird

It looks as if B/OW-OY skirted around forest fires in the Ourém region.

In the spring, B/OW-OY will return to his Breckland breeding site, hopefully to meet up with B/OW-OL and to have another go at raising chicks. For him nothing has changed – he’s doing the same again for another year. The only difference is that he is tagged now, and that provides us with insights into his world and the challenges that he and other migratory waders face. Imagine what it will be like if, next year or in the near future, he arrives back in Montijo and finds bulldozers and freshly-poured concrete, instead of mud and saltmarsh. With a new airport to contend with and yet more anthropogenic change to his world, life does not look as if it will get easier.


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.

January to June 2022

Here are brief summaries of the first nine WaderTales blogs of 2022. As ever, I am grateful to the authors of the papers that underpin the blogs; they have worked with me to make sure that I get the stories right! I have not covered every new paper; perhaps your favourite is in the pipeline or perhaps I did not happen to spot it? The blogs are described in order of publication.

Welsh Oystercatchers

To explain how flexible Oystercatchers can be in response to changes in their food supply, Katharine Bowgen has brought together long-term data collected by wader ringers and WeBS counters, and added in annual assessments of cockle stocks on the Burry Inlet (South Wales). This paper has a particular resonance, as I remember teaching students about the Burry Inlet Oystercatcher controversy of the 1970s, when complaints from shellfishers led to the deaths of thousands of birds. We understand more about the relationship between shellfish stocks and bird numbers now but what happens when Oystercatchers can’t find food? This paper makes a strong case for the protection of networks of sites, so that individuals have alternatives when needed.

Australian stock-take

One of the great joys of writing WaderTales blogs is that I get to ‘visit’ the flyways of the world without having to burn carbon. How many shorebirds use the East Asian-Australasian Flyway? is a flyway-wide stock-take of the waders that visit Australia and New Zealand, led by Birgita Hansen. It is shocking that a flock of 350 Far-eastern Curlew now constitutes 1% of the global population and that the population of Curlew Sandpipers has halved in double-quick time, but the key strength of the paper is the clear explanation of a methodology that can be used in the future, to monitor changes in numbers.

Chick vocalisation

Big analyses of data sets are very important but it’s lovely when you learn more about the natural history of species that birdwatchers know well. In Australia, Kristal Kostoglou recorded the calls of the chicks of Red-capped Plovers and Southern Masked Lapwings, that were being ringed and measured in the hand. In Chick squeaks I describe how calls get deeper with age, which is not surprising, but that the calls of males and females can become distinguishable from a very early age. Male Red-capped Plover chicks are more demanding than their sisters!

Trans-oceanic migration

There have been several recent wader papers that interpret data obtained from birds when on migration. One of the interesting questions being asked is, “Do shorebirds account for wind displacement continuously or correct for drift later?”. Navigating a vast ocean summarises Jenny Linscott’s work on Hudsonian Godwits, as they cross the Pacific Ocean and then the Gulf of Mexico, on their way from Chile to Alaska. She and her fellow authors show that flocks make continuous adjustments, demonstrating that birds ‘know where they are’ and giving them the ability to fly extremely long distances without running out of energy. There’s some clever maths too!

Hiding in the trees

In the second paper from her PhD, Triin Kaasiku looks at the breeding success of Estonian coastal waders that nest at different distances from woodland. Keep away from the trees describes these ‘edge effects’. In a part of the world where waders are in diminishingly short supply, hatching success is six time as high in open areas as in areas that are within one kilometre of forest edge. The Baltic coast used to be a haven for species such as Curlew and Dunlin but reduced grazing and forestry plantations have provided hiding places for predators. Alongside increased predation, breeding waders are also having to contend with an increasing numbers of nest inundations, arising from summer storms.

Curlew hunting

Curlew hunting stopped in Great Britain in 1982, when the declining wintering population received protection under the new Wildlife & Countryside Act. A fascinating paper by Ian Woodward and BTO colleagues teases apart the positive effects of the cessation of shooting and more benign winter weather. It is summarised as Curlew: after the hunting stopped.

I am old enough to remember when Curlew were hunted in East Anglia. The pâté made from autumn-shot birds is reputed to have been very tasty; I recall Clive Minton getting back in his land-rover and reporting that he had been offered some, when asking for permission to cannon-net Curlew on a Norfolk land-owner’s estate.

Personal appreciation of Whimbrel

On 27 April, Jenny Gill and I were at Eyrarbakki, on the south coast of Iceland. As we watched, small groups of Whimbrel were coming in off the sea. Others were resting on the seaweed-covered rocks, a few were feeding and some flew straight by. Watching waders arrive in Iceland is always magical but, from sightings of satellite-tagged Whimbrel, we could be pretty sure that these tired birds had just completed five-day, direct flights from west Africa. I could not wait to get back to base and to share our observations. It was a good excuse to round up the Whimbrel stories in other WaderTales blogs, as you can read in Whimbrels arrive in Iceland.

Power-line problems

We have seen huge changes in Iceland, since we first visited in 2000, but how are these affecting shorebirds? In the first paper of her PhD (Effects of land conversion in sub-arctic landscapes on densities of ground-nesting birds), Aldís Pálsdóttir investigated how distributions of breeding waders are affected by power-lines. She discovered significantly depressed numbers several hundred metres from the transmission lines, with Whimbrel and Redshank being the most obviously impacted. Her results are written up as Power-lines and breeding waders. With an increasing global reliance on electricity, these are important findings for planners and conservationists.

Conflict with forestry

Just a few days later, Aldís Pálsdóttir’s second paper was published. By mapping distributions of breeding waders in the vicinity of forests, she has shown that new plantations have a massive effect on distributions. In lowland Iceland, the most vulnerable species appear to be Dunlin and Oystercatcher, followed by Whimbrel, Black-tailed Godwit and Golden Plover. It should be noted that three-questers of Europe’s Whimbrel nest in Iceland, as well as half of the Golden Plover and Dunlin. Aldís and her fellow authors argue that Iceland’s waders need a strategic forestry plan. They estimate that recently-planted woodland and forests have already removed the breeding territories of tens of thousands of waders.

Blogs from previous years

WaderTales blogs in 2021

WaderTales blogs in 2020

WaderTales blogs in 2019

WaderTales blogs in 2018

WaderTales blogs in 2017


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.

Curlew: after the hunting stopped

It is estimated that 120,000 Eurasian Curlew spend the winter in Great Britain, with a further 28,300 on the island of Ireland (Note). Counts made by Wetland Bird Survey (WeBS) volunteers in Great Britain show that the winter population increased following the end of Curlew hunting in 1982 but has since decreased. A paper in Bird Study by Ian Woodward et al investigates how much the temporary recovery was ‘cause and effect’ and asks what other processes may be important, locally and regionally.

Note: Figures from reports in British Birds and Irish Birds, as summarised in the WaderTales blogs, Do populations estimates matter? and Ireland’s wintering waders.

Curlew problems

The 13 species of the Numeniini tribe (curlews, godwits & Upland Sandpiper) are in trouble, with two species probably extinct (as discussed in Why are we losing our large waders?). Eurasian Curlew is red-listed in the UK and described as ‘near-threatened’ internationally.

The wintering Curlew population of Britain and Ireland is made up of birds that move around within these islands and others that breed as far east as Russia. The breeding population of Curlews in the UK declined by 48% over the period 1995-2018, according to Breeding Bird Survey data, but numbers were probably higher still in the preceding period. Trends in other countries are mixed; across Fennoscandia there have been increases in Finland but declines in Sweden, for instance, as discussed in Fennoscandian wader factory.

In the autumn, some UK-breeding Curlew migrate south and west but there are larger arrivals, especially from Finland. Winter numbers on estuaries and wetlands are monitored by WeBS counters, with supplementary information for coastal birds collected periodically (see Waders on the coast). Curlews are site-faithful to wintering sites, so changes in abundance on an estuary will largely depend upon the annual survival of adults that use the site and the recruitment of juveniles.

To survive the winter, a Curlew needs access to sufficient food and to be able to build up fat stores so that it can cope with periods of freezing conditions, when energy loss is high and access to food is limited. In Great Britain, up until 1982 there were additional losses due to hunting. The study led by Ian Woodward aims to establish the local and broadscale factors that might have influenced annual changes in the numbers of Curlew using wintering sites.

Curlew hunting

The estuaries of Britain and Ireland are of huge importance to Europe’s Eurasian Curlew, being significantly warmer than sites in continental Europe on similar latitudes. It is estimated that at least 20% of the European population winters in the British Isles. An adult Curlew is almost as heavy as a Mallard, so it is unsurprising that the species was pursued by hunters, particularly wildfowlers, who encountered them on the foreshore and on wetland sites. When the list of species that could be legally hunted was revised, as part of work to develop the Wildlife & Countryside Act of 1981, Curlew numbers were falling. Shooting of Curlew in Great Britain stopped in 1982 but continued until 2011 in Northern Ireland and 2012 in Ireland.

The national graph from the Wetland Bird Survey (WeBS) can be divided into four sections. There was a rapid decline in wintering numbers during the 1970s, with the UK population reaching a low point in about 1980. Numbers increased rapidly for the next 15 years and then there was a period of relative stability between 1995 and 2000. Since then, the trend has been downwards.

Although not considered in this study (because annual count data are not collected) it is interesting to note that, in the period between 1997/98 and 2015/16, counts of Curlew on open coasts declined more rapidly than on estuarine sites covered by WeBS (40%, compared to 26%). See Waders on the coast.

Looking closely at the WeBS graph, signs of recovery of the UK wintering Curlew population were evident before 1982, when hunting ceased in Great Britain. With numbers falling in the late 1970s, it is possible that hunters chose not to target Curlew, either because they were worried about sustainability or because there were fewer to hunt. Sadly, there is no systematic recording of bag numbers that might help to explain why the upturn in the Curlew graph started before the species received full protection.

Detective work

Ian Woodward and his colleagues started by considering a range of potential drivers of change, other than reduced hunting pressure. Have numbers responded positively to warmer winter temperatures, and might this effect be more obvious in colder regions of the UK? Are there different trends in some estuaries, potentially linked to water quality or the ability to switch to feeding in fields?

The main data available to the BTO team were monthly WeBS counts from north-west England, the Midlands, south-west England, southern England, Anglian region, north-east England and Wales. There was particular focus on 46 estuaries with largely complete datasets and for which comparable environmental data were also available: estuary structure, the presence of coastal grassland feeding areas, potential disturbance and water quality data.

Coastal fields can provide important roosting and feeding areas for Curlew

Why did Curlew numbers change?

The analyses and detailed findings of the study can be found in the full paper in Bird Study. Here are the headlines:

  • When all of the potential drivers of change were considered, the increase in wintering Curlew numbers across the whole of the UK during the 1980s and early 1990s is most likely to have been linked to the cessation of hunting.
  • There has been a redistribution of Curlew over the period of the study, with a higher proportion of a reduced UK wintering population now wintering in the east. Many of the estuaries where numbers have been stable or there have been increases are on the east coast (including the Thames, Blyth, Tees and Alnmouth estuaries). Warmer winter temperatures may have made conditions in the east more suitable for wintering Curlew.
Protracted periods of cold weather are tough for Curlew wintering in the UK
  • Regional trends of wintering numbers were similar across the UK, although the exact timing of the post-hunting peak varied between regions. Numbers are still increasing in north-east England, the coldest region for which data were analysed.
  • In addition to the reduction of direct mortality, Ian Woodward and colleagues suggests that the cessation of hunting may have led to reduced disturbance. Although wildfowlers will still have been shooting ducks and geese, they will not have been directly targeting areas with Curlew flocks.
  • The research team did not detect an effect of changes in water quality, so it is unlikely that the clean-up of estuaries, prompted by the EU Water Framework Directive, had a major effect on the change in Curlew numbers.
  • Curlew numbers decreased during winters with higher numbers of frost days but increased in the following years. An example of the dramatic effect of particularly cold weather was described by a wildfowler, operating on the Wash (Anglian region) in 1991, who came across a small flock of Curlew that had died where they stood, while roosting on the foreshore.
  • In the paper, there is an extensive discussion about the factors that may lead to a redistribution of Curlew, after a period of cold weather. The authors suspect that local redistribution and behaviour changes, rather than long-distance movements, may be the main drivers of changes in annual numbers related to cold weather. Sadly, there is insufficient information to know what factors are at play. How many birds move out of areas to escape freezing conditions but then return to their old wintering areas in subsequent years? Is there a longer-term redistribution of some adults following a cold winter? Do new recruits take advantage of gaps left by missing birds in the winter after a cold-weather event? We need to know more about what happens to individuals in periods of extremely cold weather, which should be increasingly possible now that more Curlews are colour-ringed.

Read more

The analyses presented in the paper suggest that the period of increase, following the cessation of hunting, lasted for around 13 years. Since 1995, declines have resumed. We know that annual survival of the UK-wintering Curlew population is remarkably high, as discussed in another BTO paper by Aonghais Cook et al and described in More Curlew chicks needed. There is very strong evidence that conservation action to support this red-listed species needs to focus upon improving breeding season productivity.

Sadly, the best days for the UK’s wintering Curlew appear to be behind us, with a seemingly relentless decline in numbers since the winter of 1999-2000. This paper could not have been written without WeBS counters and, thanks to them, we will be able to discover what happens next.

The full Bird Study paper is:

Assessing drivers of winter abundance change in Eurasian Curlew Numenius arquata in England and Wales. Woodward, Ian D., Austin, Graham E., Boersch-Supan, Philipp H., Thaxter, Chris B.and Burton, Niall H.K. Bird Study. https://doi.org/10.1080/00063657.2022.2049205


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.

The flock now departing

“The flock now departing from the tideline is bound for Beauvais. Curlew can change here for destinations in Germany and Russia”. It’s fascinating to wonder what might be happening when a flock of waders takes to the air, gains height and sets off in a particular migratory direction. With more individuals wearing tracking devices, it was only a matter of time until someone would have data that provides clues as to the association of individuals within flocks – as we see in a 2021 paper in Bird Study by Frédéric Jiguet and colleagues: Joint flight bouts but short-term association in migrating Eurasian Curlews.

Setting off on migration

When we get on a plane to a particular destination, everyone else who is on the same journey has chosen to travel at the same time and we all know where we are going. Each of us has checked that we have what we need for the journey and has a plan of what to do when we land – whether that involves a short shuttle to home or a lay-over before catching another flight.

For waders, planning must be more random? It’s presumably safer and more efficient to be part of a flock but how do you know which flock to join, who organises the schedule and is information shared? We can get some clues from observations of departing migratory flocks. In estuaries, there is often the chatter (which is hard to interpret but tells us that something is about to happen), then the first birds take to the air and start to gain height. A few birds may peel off and return to the tide-line while other birds take off and catch up with the departing flock. As the birds gain height, the direction of travel becomes clearer and more birds may decide to return to the mudflats. There is now a migratory flock of birds that are committed to flying in a particular direction. We have no idea how that direction was chosen, of course, but there is a plausible explanation as to how the flock might have formed.

This is not the last decision that members in a flock might need to make. Tired birds may need to drop out of the flock, to take a break. Perhaps some birds might realise that the direction of travel does not work for them and the flock might break up?

It can be just as chaotic when a flock reaches a destination. Watching Black-tailed Godwits arriving in South Iceland in April is fascinating; a tired flock might come in off the sea, land and start drinking, before either resting or feeding, but this is not always the case. On a clear day with fair winds, the flock may split up, with some birds keen to keep flying and others happy to stop. This reinforces the impression that a flock only maintains its integrity as long as being in a group meets the needs of the individuals it contains.

Tracking Eurasian Curlew

Understanding migration is an important element of Curlew conservation studies in France.

In their Bird Study paper, Frédéric Jiguet and colleagues describe four cases of joint migration by tagged Eurasian Curlews. Their observations were a byproduct of research aimed at a better understanding of the origins and migration patterns of Curlew that spend the winter in France. The species has been a popular target for French hunters, many of whom are keen to resume shooting, as you can read in the WaderTales blog Black-tailed Godwit and Curlew in France. It is estimated that more than 7000 Curlew were shot in France annually prior to 2008, when the first moratorium was put in place.

There is an urgent need to understand links between wintering sites and breeding sites, especially in areas where the species is in rapid decline. How important is France to the Curlew that breed in countries such as Poland and Germany? The current ban on shooting is not perfect (see paper in Forensic Science International: Animals and Environments) but it is better than nothing, given rapid declines in Curlew numbers across Europe.

In winter and spring 2020, the research team deployed 61 GPS tags on Curlews in France and Germany, hoping to learn more about breeding ecology and migratory connectivity. In a separate study, in Poland, four captive-bred juvenile curlews were tagged and released in July 2020. Between them, these tagged birds led to four cases of joint migration bouts. One case concerned two adults leaving their wintering ground for the pre-breeding migration. Two other cases were birds leaving their breeding grounds at the start of migration. The last one was of two juveniles initiating their first flights to the non-breeding grounds.

Spring migration

About 27,500 Curlew spend the winter in France (see French report produced jointly by government and shooting groups), representing about 5% of the European population. Tracking has shown that these birds breed in Belgium, Germany, Sweden, Finland, Austria and Russia (see article published by Bird Guides) but there are reports of ringed birds from many other countries, including the threatened populations in Poland and the UK.

Thousands of Curlew spend most of the year in coastal France – representing 5% of the European population.

Return migration to breeding areas takes place in early April. Frédéric Jiguet reports ‘groups of curlews rising high in the sky at sunset’ from the Moëze-Oléron and Baie de l’Aiguillon Nature Reserves in southwest France.

Back-mounted GPS tag

On 17 April 2020, two individuals wearing tracking devices left their French wintering site at sunset, between 22:37 and 22:40. They became closely associated just ten minutes prior to the start of migration, having typically stood 100 metres apart during the previous hour. They flew together for seven hours before making a stop-over north of Paris, between Creil and Beauvais, in the Thérain Valley.

  • 200185 was on its way again two hours later, flew for six hours, stopped again in the Netherlands and arrived in Norderney, an island of the Wadden Sea in northern Germany, at 18:39 on 19 April.
  • 200187 had a much longer layover in the Thérain Valley, making another evening departure at 20:05 on 18 April. It continued migrating, in stages, for more than a month, crossing the Ural Mountains and reaching the Yamalia municipality, in Asian Russia.

Two birds that had been on the same flight from southwest France ended up in very different locations and at very different times. The German Curlew reached its summer destination five weeks before the Russian bird arrived on territory, the latter having secured places on several different ‘international flights’ as it made its way east and north (see figure below).

Post-breeding migration

After breeding, adult Curlew head towards wintering sites, perhaps stopping to moult en route. Some birds do not travel far; for instance, there are colour-marked birds that winter on the Wash (eastern England) and fly just a few kilometres inland to breed. The Bird Study paper includes reports of two occasions when tagged birds have been spotted migrating together from German and French study areas. Southerly migration of all four birds commenced during the evening of 17 June 2020.

French birds: Two individuals departed simultaneously from Deux-Sèvres (central France) between 19:16 and 19:17 for a non-stop southward flight and arrived together at Ria de Treto estuary, in northern Spain on 18 June at 05:49. The two birds departed separately from this stopover site the same day (18 June).

  • 200201 departed at 18:18, for a non-stop flight to Kenitra (Morocco) where it stopped briefly, before moving a short distance north to Merja Zerga.
  • 200204 departed at 19:46 and flew to the Atlantic coast of Spain, stopping for 2.5 hours on Isla Cristina and then flying to its final destination at Ilha de Tavira, in southern Portugal.

After separation, the two birds travelled at different times but followed quite similar routes and even flew at similar altitudes.

German birds: On 17 June 2020, two individuals departed simultaneously from Dollar Bay, in the Wadden Sea National Park. 201075 began migration between 18:58 and 19:03. After five kilometres, if flew over 201072 at an altitude of about 190m. The latter bird took off and joined 201075. They then flew together for five hours, landing in the Rhine-Meuse-Delta (Netherlands).

201075 departed from the Rhine-Meuse-Delta on 20 June and, after one more stop-over, reached its final destination on the Brittany coast on the evening of the next day.

201072 was also bound for Brittany. It departed on 23 June and flew non-stop for six and a quarter hours.

Migration of juveniles

It will be hard to satellite-tag enough wild juvenile waders to pick up instances of marked individuals migrating in the same flocks. However, head-starting may give some clues as to what might happen when naïve flocks of juvenile waders start their migratory journeys, months after the parents have left them. The full story is told in the paper but a quick summary tells us that two Polish head-started Curlews were released on 1 July, departed together on 5 August and landed in the Baie de l’Aiguillon (France) on 8 August. In between times, they came close to landing in The Netherlands, flew along the English coast from Dover to Poole, flew a long way south and west around the Bay of Biscay and then northeast to the coast of France. They both spent the winter in the Baie de l’Aiguillon but not together.

Although it will be difficult to compare the migratory behaviour of wild-caught and head-started wader chicks using satellite tags, just because of probabilities and costs, researchers are building up datasets using smaller geolocators and GPS tags. Here’s hoping that we will soon know more.

Paper

The nutrient-rich mud of Ile Madame

This paper provides observations of just four instances of joint migration but each story is fascinating. They give us insights as to what might be possible as devices get smaller and when land-based tracking stations collect signals from passing birds. For the moment we can use our imagination to interpret the chattering of pre-migratory flocks of waders, the appearance of a small flock of waders at an inland spot in spring and the noisy arrival of a lone Curlew on an estuary in June.

The paper contains a lot more detail about the methods used to collect and interpret data and a discussion that sets Curlew migration within a much broader conceptual context. Here’s a link:

Joint flight bouts but short-term association in migrating Eurasian curlews.

Frédéric Jiguet, Pierrick Bocher, Helmut Kruckenberg, Steffen Kämpfer, Etienne Debenest, Romain Lorrillière, Pierre Rousseau, Maciej Szajdaand & Heinz Düttmann. Bird Study. DOI/10.1080/00063657.2021.1962805

Wintering Curlew from as far away as Russia and Sweden can be found roosting in these French saltmarshes

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.

More Curlew chicks needed

There are three ways to increase the number of Eurasian Curlew in the UK; boost chick production across the breeding range, find ways to ensure more chicks recruit to the breeding population and/or maximise the lifespan of breeding birds. In a paper in Biological Conservation, Aonghais Cook and colleagues show that, while continued protection of wintering sites is really important, there appears to be little scope for conservation action that can further increase annual survival rates. The focus for conservationists has to be on increasing chick productivity and recruitment.

Curlew in Britain and Ireland

The once-common breeding Curlew is becoming harder to find in many areas. We know that productivity is generally low but could reduced annual survival rates also be contributing to the speed of disappearance? Here’s a quick summary of the story so far.

  • The Eurasian Curlew is designated as ‘near threatened’, as discussed in this WaderTales blog.
  • A 2017 paper by Sam Franks and BTO/RSPB colleagues described the main factors associated with the species’ decline in Great Britain. This work is summarised in a WaderTales blog called Curlews can’t wait for a treatment plan.
  • Estimated breeding population declines since 1995 are 69% in Wales, 59% in Scotland and 31% in England (Breeding Bird Survey). This is not as bad as in Ireland, where 96% were lost between the 1980s and 2015-2017. See Ireland’s Curlew Crisis.
  • Huge numbers of Curlew cross the North Sea at the end of the summer, particularly from Finland. Recent population estimates show that British wintering numbers dropped by 14% in just eight years, with an Irish decline of 13% in five years. See two reviews of wader population estimates, based upon waterbirds papers in British Birds and Irish Birds.

Survival of adult Curlews

As discussed in Measuring shorebird survival, a change in adult survival rates can have a huge effect on shorebird populations. If a species’ annual survival rate drops from 90% to 80% then numbers can half in just six years. We have seen these sorts of dramatic declines in populations of waders that travel between Russia/Alaska and Australia. There’s more about this in Wader declines in the shrinking Yellow Sea.

There are several factors that could be affecting survival rates of British-wintering Curlew:

  • Warmer winters might be expected to lead to increased survival rates.
  • The shooting ban, introduced in 1982 in response to declining Curlew numbers, was specifically designed to increase survival rates.
  • As local wintering populations have dropped, competition for resources could have dropped, potentially leading to increased survival rates.

In their paper about survival rates of Curlew in North Wales, published in Bird Study in 2013, Rachel Taylor and Steve Dodd detected an increase in apparent survival from 86.9% to 90.5% that coincided with the cessation of hunting. They also found that mechanical cockle harvesting in the mid-1990s occurred at the same time as a reduction in apparent survival rate of Curlew from 95% to 81%, indicating the potential for management changes to have huge, unintended consequences for wintering Curlew.

Amassing the data

The research team analysed recoveries of Curlew marked as chicks and adults in the breeding and winter periods, in order to estimate annual survival and the proportion of birds available to recruit into the breeding population.

Thanks to the efforts of skilled, volunteer ringers, two large data-sets were available, collected during the period 1970 to 2018:

  • A total of 1293 adult birds, 144 juveniles and 14,277 chicks were ringed in their breeding grounds across Great Britain.
  • During the winter period, 4403 Curlew were caught and ringed in five key sites – the Severn Estuary, the Tees Estuary, the Wash, Traeth Lavan and the Moray Firth (see map). Supplementary colour-ring sightings were available for the Wash, Tees and Severn.

Full details of how data were used and how models were developed are provided in the paper.

How well do Curlew survive?

Analysis of breeding season data for the period 1970 to 2018 indicates that the average annual survival was 89.8% (confidence interval 0.871–0.920) for adults and 32.6% (0.278–0.378) for first-years. The period of steepest population decline, between 1983 to 1991, coincided with lower survival in both age classes. Encouragingly, since 1996, survival has increased to 92.2% (0.886–0.948) for adults and 39.0% (0.304–0.484) for first-years.

The British and Irish wintering population of Curlew is drawn from a vast area, with birds arriving from as far as Russia and lots of birds from Finland. In a recent breeding wader report covering the Fennoscandia region, no overall change in Curlew numbers was detected, with declines in Norway and Sweden balanced by increases in Finland (see Fennoscandian Wader Factory). From 1970 to 2018, survival rates of UK wintering Curlew averaged 88.4% (0.875–0.893), consistent with survival rates of the British breeding population (above).

Survival varied over time and between the five study sites but has been generally greater than 90% in recent years. Increases in survival were recorded on the Severn Estuary and The Wash.

Curlew struggle in winters with large number of frost-days and survival rates drop significantly, both in that winter and over the subsequent year

Survival was lower in winters with a greater number of days of air frost, an effect exacerbated in successive cold winters. Cold weather may have contributed to low survival in the 1980s, a pattern also evident in the analysis of breeding season data.

Resources may limit numbers. The study suggests that, for four out of five sites, survival was lower in years in which the number of Curlew on a site was higher.

Nationally, the research team found no strong evidence that the hunting ban had increased survival rates. However, there appeared to be local effects on The Severn Estuary and on the Wash. It is unfortunate that national bag data are not available to indicate whether Curlew hunting was particularly prevalent in these two estuaries in the period prior to 1982.

What does this all mean for Curlew conservation?

Birdwatchers are helping to monitor annual survival rates by reporting sightings of colour-marked birds

Since 1996, the mean annual adult survival rate of the British Curlew breeding population has been about 92%. Despite this high number, the Breeding Bird Survey tell us that there has been an observed decline in breeding numbers of 3% per year. Demographic modelling suggests that four breeding pairs must be producing an average of only one chick per year between them. This low figure may come as no surprise to Curlew fans.

To achieve sustainability, the authors conclude that the current figure of 0.25 chicks per pair needs to rise to 0.43 chicks per pair. There are estimated to be 58,000 pairs of Curlew in Great Britain (paper in British Birds). Currently they might be producing about 14,500 chicks each year, on average, and they need to produce nearly 25,000 chicks. British Curlew need to fledge 10,000 more youngsters – every year – just to arrest the decline in numbers.

Personal reflections

Currently, annual survival rates of adults are consistently high but a couple of cold winters, changes to shellfish policy, tidal barrage developments, inappropriately-sited wind turbines and unrestricted disturbance could all have serious negative effects. It is important that we continue to protect the UK’s estuaries and the grassland feeding and roost sites that fall outside their boundaries.

Many Curlew spend significant amounts of time on farmland and recreational land that is not protected in the same way as estuarine habitats

There are a couple of gaps in our knowledge about Curlew demography. When do Curlews first breed and what are survival rates during the ‘teenage’ pre-breeding years? A working hypothesis would be that most breed at age two, with possibly some earlier and probably some later. More colour-ringing of chicks will hopefully provide better data on recruitment age and teenage survival rates. This issue was discussed in Teenage waders. In the meantime, perhaps more thought needs to be applied to avoiding disturbance of non-breeding flocks during the summer holiday season?

It is going to be important to understand how quickly juveniles recruit to breeding populations

It almost goes without saying – Curlews need to produce more chicks. Local conservation initiatives, whether by tenant farmers or dukes with vast estates, will help but raising 10,000 more chicks per year will likely require changes in land management policies. Can agri-environment initiatives be refined to deliver more Curlew? How do we integrate tree-planting and upland conservation priorities? Where should wind turbines be sited? And so much more!

Paper

In their summary of their paper, Aonghais Cook et al concluded that “In addition to increasing productivity, effective conservation strategies will need to maintain high levels of survival, which requires an improved understanding of population connectivity and demographic variation throughout the annual cycle.”

The full paper can be read here:

Temperature and density influence survival in a rapidly declining migratory shorebird.

Aonghais Cook, Niall Burton, Stephen Dodd, Simon Foster, Robert Pell, Robin Ward, Lucy Wright & Robert Robinson. Biological Conservation


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.

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.


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.

Curlews and foxes in East Anglia

blog chicksWith Curlew populations in free-fall across much of the British Isles, researchers are trying to understand the reasons for poor breeding performance. At the same time, several groups are trialling emergency interventions, such as predator control and predator exclusion, to try to boost the number of fledged chicks. Sharing knowledge is crucial, so it’s great that a 2020 paper by Natalia Zielonka and colleagues in Bird Study adds to our understanding of nest-site selection and the reasons for nesting failures.

Breckland Curlew

When we think of Britain’s breeding Curlew, the traditional image that comes to mind is moorland, where displaying birds deliver their haunting, bubbling call across upland heather moor and sheep pasture. In lowland East Anglia, in the east of England, things are very different. Some Curlew nest on Breckland heaths, which are structurally similar to moorland, but you can also find nests in sugar-beet field, in military training areas and around airfields.

The Eurasian Curlew is now categorised as Near Threatened by IUCN & BirdLife International, due to populations declines (see Is the Curlew really near-threatened?). Figures from the Breeding Bird Survey for the period 1995-2017 show that the situation in England (30% decline) is less bad than Scotland (down 61%) or Wales (down 68%). The species is now too thinly spread to be monitored in Northern Ireland but we know that the breeding population in the Republic of Ireland dropped from 3,300 pairs to just 138 pairs in 30 years (more in Ireland’s Curlew Crisis). In this context, the hot-spot in Breckland (see left-hand map from Bird Atlas 2007-11) is significant, as is the fact that there are four 10-km squares in East Anglia where an increase in density was noted between 1988-91 and 2008-11 (right).

blog maps

Problems for Curlew

The main driver of UK Curlew decline is low breeding productivity, attributable to predation and reduced quality of breeding habitats (see review by Franks et al., summarised in Curlews can’t wait for a treatment plan). Research has informed habitat provision and demonstrated that legal predator control (of foxes, crows, stoats and weasels) can increase Curlew breeding success and abundance – but not in all cases.

blog flyingMuch of the research underpinning the above review was conducted in upland areas. What is happening in the flatlands of East Anglia and might any differences explain the apparent resilience – or even growth – of this population? Most lowland Curlew breed on dry grasslands and heathland, where physical ground-disturbance is increasingly advocated as a land management technique for other rare, scarce and threatened species, such as Stone-Curlew and Woodlark. How do these interventions affect breeding Curlew in the same areas?

Study site

Natalia and her colleagues studied Curlew in two extensive grass-heath sites that differed in predator density and management. Across both sites, vegetation structure had been modified, using ground-disturbance plots, as part of a wider multi-taxa experiment, aimed at increasing biodiversity and supporting key species such as Woodlark (paper in Ibis) and Stone Curlew (paper in Biol. Conserv.).  This disturbance involved creating  2 to 4 hectare plots of deep- or shallow-cultivated ground within the wider grassland/heathland environment.

Before the experiment began, and based on previous research elsewhere, it was assumed that Curlew would avoid physically-disturbed areas, given that Curlew have been shown to prefer to nest in rougher habitats with longer grass swards.  Wherever the Curlews decided to nest, it was predicted that nest survival would be higher on the site with lower predator density, that most clutches would be taken at night and that success would decrease through the season.

blog STANTA

The study was carried out in 2017 and 2018 across the Stanford Military Training Area (STANTA) and Brettenham Heath. Both sites contain extensive areas of dry grassland and grass-heath, surrounded by arable farmland and woodland. Generalist predator control on STANTA was largely carried out around Pheasant release pens, with little or none in most of the surrounding, open arable farmland and woodland. In contrast, Brettenham Heath was subject to continuous predator control across the whole site and in surrounding arable farmland (but not woodland). Brettenham Heath is also enclosed by a two-metre high deer fence with a single electric strand set 50 cm above the ground. There is more about the two sites in the paper (link below).

blog Brettenham

Across both sites, 64 experimental ground-disturbance plots were established in early 2015 and subsequently disturbed annually, using a variety of management techniques. Areas on STANTA that might have contained unexploded ordinance could not be disturbed – and were trickier to survey! In both years, nests were located between mid-April and late June, by visiting any area where Curlew had been seen and looking for adults sitting on, or walking back to, a nest.

Evidence of nest success

blog chickTo determine the date and timing of nest failure, temperature sensors were placed under the eggs. Nests were remotely checked every three-to-seven days, to confirm adults were still incubating, and the scrape was visited once a week to record any predation events (e.g. partial clutch predation). From three days before the predicted hatch date, nests were remotely monitored daily to accurately determine their fate. After hatching, the nest site was visited every three-to-five days, to observe adults and chicks from a vehicle, continuing until the chicks fledged or the breeding attempt had failed.

Three types of evidence can help to reveal the outcome of a nesting attempt:

  • Small chicks or alarming adults are seen in the vicinity of an empty nest.
  • Small shell fragments are found in the nest cup, indicating that chicks have hatched.
  • The temperature sensor reveals that adults kept the eggs warm for the whole incubation period.

A sudden drop in nest temperature can reveal the timing of predation and hint at the culprit. Other studies have shown that nocturnal visits are usually by foxes or badgers, or occasionally hedgehogs. In 2018, infra-red cameras, triggered by movement, were used on ten nests.

blog camera

Where to nest?

Unexpectedly, given that breeding Curlew in the uplands are usually associated with areas with longer grass, Breckland pairs were five- to six-times more likely to select disturbed plots than undisturbed grassland. Nearly half of nests were located on disturbed grassland across both years, which only occupied about 8% of the grassland area. Curlew are long-lived and site-faithful, so disturbed plots may have been created within already-established breeding territories. Whilst physical-disturbance interventions are unlikely to bring birds in from the wider landscape, this study shows that nest placement was more likely to occur on disturbed grassland within a pair’s home range. This suggests that local-scale management can influence nest placement within established breeding sites.

Disturbed grassland is characteristically bare and short compared to uncultivated grassland. Curlew may have placed nests in this habitat because it allows greater vigilance and/or because there is a greater abundance of some important prey for chicks than the surrounding grassland (information in paper by Hawkes et al.). Most nests were on shallow-cultivated plots (created with a rotary rotovator), with few on the barer deep-cultivated plots (created with an agricultural plough). There was taller vegetation and more ground cover in the shallow-cultivated plots.

blog tractors

Nest survival rates                                                                                                                       

Over the course of the two summers, 44 Curlew nests were monitored, of which 32 failed. 29 nests were predated, one was trampled by livestock, one was mown and one pair deserted (and then renested). Mean overall nest survival probability from start of incubation to hatching was 0.70 ± 0.18 SE at Brettenham Heath (where there was intensive predator control and fencing) and 0.16 ± 0.06 at STANTA (where predator control was patchy and the site was open). Overall breeding productivity was 0.16 ± 0.01 SE fledged chicks per nesting attempt. As predicted, daily nest survival rate decreased through the course of the nesting season.

The figure for STANTA represents low nesting survival, especially when compared to other lowland sites in England, and re-nesting following failure appeared infrequent. Productivity here is likely to be substantially below that required to maintain a stable population. Importantly, nest survival across the two sites was not influenced by ground-disturbance, which suggests that this management intervention did not increase nest exposure to predators.

Identifying the predators

D4_sheep_predation_20May

Of the ten 2018 nests with nest cameras:

  • Three nests survived through to hatching.
  • Four were predated by fox (one during the day and three at night).
  • One nest was predated by an unknown predator (following camera malfunction).
  • One nest was predated by a sheep (two out of four eggs remained but incubation was not resumed and the other eggs were later taken by a crow). The camera footage of sheep v Curlew was provided by Natalia Zielonka.
  • A single-egg, late-season re-nesting attempt was abandoned three days after camera deployment (egg was later taken by a crow)

There was no effect of nest cameras on daily nest survival rate.

G1_Fox_predation_20May

Parent Curlews removed some of the temperature loggers but there were sufficient data to identify the timing of predation events for 23 nests. Of these, 17 events were during the night (13 nocturnal, four crepuscular) and six during the day. This nocturnal timing of nest predation was consistent with mammalian rather than avian predation, with camera traps and other evidence suggesting that foxes were the main perpetrators. The camera footage of fox v Curlew was provided by Natalia Zielonka.

As expected, from the levels of predator control, nest survival was lower at STANTA than Brettenham Heath. The latter site was both fenced and subject to lethal fox control, delivering a breeding productivity well above that considered necessary for a sustainable population of Curlew. It is possible that a few fenced sites and others with high levels of predator control might be disproportionately responsible for the fact that Curlew appear to be doing better in the Brecks than in other areas.

Conservation implications

blog bare nestThe key finding of this project is that physical ground-disturbance, which is advocated as a conservation measure within lowland dry grassland and grass-heath for many rare, scarce and threatened species, also provides suitable Curlew nesting habitat, with no reduction in nest survival. Implementing ground-disturbance, particularly through shallow-cultivating, in areas with few or no mammalian nest predators, could provide a useful management tool for attracting breeding Curlew to safer areas.

An intervention to help Stone Curlew and Woodlarks was never designed to assist Curlew. Indeed, there was a prediction that Curlew would actively avoid areas that had been rotovated, in order to create bare patches in which the target species could nest and feed. In a rare case of serendipity, experimental research by Rob Hawkes, Paul Dolman and others has delivered a way of encouraging Curlew to nest in relatively small plots (2-4 hectares) around which it may be possible to run an electric fence. One of the big questions “How can we protect Curlew nests when they have such big territories?” might have become easier to answer. If ‘Curlew plots’ can be created within known territories, or even areas that seem good for Curlew, then they can potentially become the focus for protection.

Having spotted that Curlew seemed to be attracted to disturbed areas it is great that Natalia Zielonka was able to study this population, in order better to understand constraints that seem to be restricting productivity. Her research was undertaken as part of her MSc in Applied Ecology and Conservation at the University of East Anglia,

Further reading

blog RARThe paper at the heart of this blog is:

Placement, survival and predator identity of Eurasian Curlew Numenius arquata nests on lowland grass-heath. Natalia B. Zielonka, Robert W. Hawkes, Helen Jones, Robert J. Burnside & Paul M. Dolman.

Bird Study. DOI 10.1080/00063657.2020.1725421


GFA in IcelandGraham (@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.

 

Nine red-listed UK waders

blog rpTHIS BLOG HAS BEEN UPDATED

Birds of Conservation Concern 5 (published on 1 Dec 2021) saw the promotion of Dunlin and Purple Sandpiper to the Red List.

Please click here to switch to: Eleven waders on the UK Red List

If you ask British birdwatchers to name the nine wader species that are causing the most conservation concern in the UK, they would probably not include the Ringed Plover. Curlew may well be top of the list, even though we still have 58,500 breeding pairs in the UK*, but would people remember to include Ruff? This blog is written to coincide with the publication of Red67, an amazing collaboration of artists and essayists that highlights and celebrates the 67 species on the current UK red list, nine of which are waders.

*Avian Population Estimates Panel report (APEP4) published in British Birds

What’s a Red List?

The UK Red List is made up of a strange mixture of common and rare species. Nobody will be surprised to see fast-disappearing Cuckoo, Turtle Dove and Willow Tit, but why are 5.3 million pairs of House Sparrow in the same company? The list is very important because it helps to set the agenda for conservation action, the way that money for research is distributed and focuses attention during planning decisions. The main criteria for inclusion are population size – hence the inclusion of species that are just hanging on in the UK, such as Golden Oriole – and the speed of decline of common species. Data collected by volunteers, working under the auspices of the British Trust for Ornithology, measured a population decline for House Sparrow of 70% between 1977 and 2017, which is worrying enough to earn this third most numerous breeding species in the UK a place in Red67.

blog bookIn his foreword to Red67, Mark Eaton, Principal Conservation Scientist for RSPB, explains how listing works. The Birds of Conservation Concern (BOCC) system, through which the Red List and Amber List are determined, uses a strict set of quantitative criteria to examine the status of all of the UK’s ‘regularly’ occurring species (scarce migrants and vagrants aren’t considered), and uses a simple traffic light system to classify them. There are ‘Red’ criteria with thresholds for rates of decline in numbers and range, historical decline and international threat (if a species is considered globally threatened it is automatically Red-listed in the UK), together with a range of other considerations such as rarity, international importance of UK populations, and how localised a species is. If a species meets any of the Red List criteria it goes onto the Red List.

The Red67 book – words meet art

Red67 is the brainchild of Kit Jewitt, a.k.a. @YOLOBirder on Twitter. It’s a book featuring the 67 Red-listed birds, each illustrated by a different artist alongside a personal story from a diverse collection of writers. Proceeds will support Red-listed species conservation projects run by BTO and RSPB. Kit describes Red67 as 67 love letters to our most vulnerable species, each beautifully illustrated by some of the best wildlife artists around, showcasing a range of styles as varied as the birds in these pages. My hope is that the book will bring the Red List to a wider audience whilst raising funds for the charities working to help the birds most at need.

This blog is about the nine waders in the book, but there are 58 other fascinating species accounts and wonderful artworks. Each species account starts with a quote from the story in the book and is accompanied by a low-resolution version of the artwork (Ringed Plover is illustrated above).

Lapwing

blog l“It’s the crest that does it for me – that flicked nib stroke, the artist’s afterthought” – Lev Parikian

The Lapwing used to nest across the whole of the United Kingdom and was a common bird in almost every village. It’s still the most numerous breeding wader in the UK, with 97,500 pairs (APEP4), beating Oystercatcher by just 2,000 pairs. Numbers dropped by 54% between 1967 and 2017, according to BirdTrends 2019, published by BTO & JNCC. Huge losses had already occurred over the previous two centuries, as land was drained and vast numbers of eggs were collected for the table. The Lapwing is now a bird associated with lowland wet grasslands and the uplands, rather than general farmland.

Red-listing has been important for Lapwing, increasing the profile of the species and encouraging the development of specific agri-environment schemes targeted at species recovery. These include ‘Lapwing plots’ in arable fields and funding to raise the summer water tables in lowland grassland. Several WaderTales blogs describe efforts to try to increase the number of breeding waders in wet grassland, especially Toolkit for Wader Conservation. The loss of waders, and Lapwings in particular, from general farmland is exemplified in 25 years of wader declines.

Ringed Plover

blog rp graph“They gather at high tide like shoppers waiting for a bus: all facing the same direction, and all staring into the distance” – Stephen Moss

One of the criteria that the BOCC panel takes into account, when constructing the Red List, is the responsibility the UK has for a species or subspecies in the breeding season, during winter or both. The Ringed Plovers we see in the UK in the winter are almost exclusively of the hiaticula subspecies; birds that breed in southern Scandinavia, around the Baltic, in western Europe and in the UK. There are only estimated to be 73,000 individuals in this subspecies, so the 42,500 that winter in the UK constitutes a large percentage of the Ringed Plovers that breed in many of these countries.

The Wetland Bird Survey graph alongside shows a decline of over 50% between 1989 and 2014. At the start of the period, Ringed Plover numbers were at an all-time high but this is still a dramatic and consistent drop. Numbers have stabilised and may even have increased slightly but Ringed Plovers need some good breeding years. Disturbance is an issue for breeding Ringed Plovers, which share their beaches with visitors and dogs, and could also potentially be a problem in the winter (see Disturbed Turnstones).

Dotterel

blog dot“I want you in the mountains. Summer breeze. At home. Doing your thing. So don’t go disappearing on us, okay?” – Fyfe Dangerfield

The Dotterel is a much clearer candidate for Red67 – there’s a small population in a restricted area and numbers have fallen. The detailed reasons for decline may still need to be nailed down but candidate causes such as declining insect food supplies and the increasing numbers of generalist predators are probably all linked to a changing climate – squeezing Dotterel into a smaller area of the mountain plateaux of Scotland.

There’s a blog about the decline in Dotterel numbers called UK Dotterel numbers have fallen by 57%, based upon a paper that uses data up until 2011. At this point, the population was estimated at between 280 and 645 pairs. There has been no suggestion of improvement since that blog was written. Interestingly, Dotterel may have a way out of their predicament, as we know that marked individuals move between Scotland and Norway in the same breeding season. See also Scotland’s Dotterel: still hanging on.

Whimbrel

blog whim“How often do Whimbrels pass overhead nowadays? Unseen and unheard, their calls mean nothing to most of us” – Patrick Barkham

Most British and Irish birdwatchers think of Whimbrel as spring migrants, enjoying seeing flocks of Icelandic birds when they pause on their way north from West Africa (see Iceland to Africa non-stop). There is a small, vulnerable population nesting almost exclusively on Shetland. The latest estimate is 310 pairs (2009), down from an estimate of 530 pairs, published in 1997. Many pairs have been lost from Unst and Fetlar and this blog about habitat requirements might give clues as to why: Establishing breeding requirements of Whimbrel.

The curlew family is in trouble across the Globe, potentially because these big birds need so much space (see Why are we losing our large waders?)

Curlew

blog cu“… achingly vulnerable in a world that is battling to hold onto loveliness” – Mary Colwell

What more can be said about Curlew, ‘promoted’ to the red list in 2015 and designated as ‘near threatened’ globally. Most significant is the story from Ireland, where 94% of breeding birds have disappeared in just 30 years. These blogs provide more information about the decline and review some of the reasons.

There are more Curlew-focused blogs in the WaderTales catalogue.

Black-tailed Godwit

blog blackw“A glimpse of terracotta is obscured by ripples of grass, dipping gently in the breeze” – Hannah Ward

Winter Black-tailed Godwit numbers are booming but these are islandica – birds that have benefited from warmer spring and summer conditions in Iceland, as you can read here in: From local warming to range expansion. Their limosa cousins are in trouble in their Dutch heartlands (with declines of 75%) and there have been similar pressures on the tiny remaining breeding populations in the Ouse and Nene Washes. Here, a head-starting project is boosting the number of chicks; so much so that released birds now make up a quarter of this fragile population. Red-listing has shone a spotlight on this threatened subspecies, attracting the funding needed for intensive conservation action.

Ruff

blog ruff“They look a bit inelegant – a small head for a decently sized bird, a halting gait, and that oddly vacant face” – Andy Clements

There are two ways for a species to be removed from the Red List – extirpation (extinction in the UK) and improvement. Temminck’s Stint came off the list in 2015, having not been proven to breed since 1993, and Dunlin was moved to Amber at the same time. Ruff are closer to extirpation than they are to the Amber list. There is a spring passage, mostly of birds migrating from Africa to Scandinavia and the Baltic countries, and some males in glorious breeding attire will display in leks.

250 years ago, Ruff were breeding between Northumberland and Essex, before our ancestors learnt how to drain wetlands and define a hard border between the North Sea and farmland. Hat-makers, taxidermists and egg-collectors added to the species’ woes and, by 1900, breeding had ceased. The 1960s saw a recolonisation and breeding Ruff are still hanging on. There are lekking males causing excitement in sites as disparate as Lancashire, Cambridgeshire and Orkney, and there are occasional nesting attempts. Habitat developments designed to help other wader species may support Ruff but the situation in The Netherlands does not suggest much of a future. Here, a once-common breeding species has declined to an estimated population of 15 to 30 pairs (Meadow birds in The Netherlands).

Red-necked Phalarope

blog rnp“… snatching flies from the water in fast, jerky movements, droplets dripping from its slender beak” – Rob Yarham

Red-necked Phalaropes that breed in Shetland and a few other parts of northern Scotland appear to be an overflow from the Icelandic population; birds which migrate southwest to North America and on to the Pacific coastal waters of South America. This BOU blog describes the first track revealed using a geolocator.

The Red-necked Phalarope was never a common breeder and came under pressure from egg-collectors in the 19th Century. Numbers are thought to have recovered to reach about 100 pairs in Britain & Ireland by 1920. Numbers then fell to about 20 pairs by 1990, so the latest estimate of 64 pairs (The Rare Breeding Birds Panel) reflects conservation success. Given the restricted breeding range and historical declines, it is unlikely that the next review will change the conservation status from Red to Amber, despite the recovery of numbers.

Woodcock

blog wk“… taking the earth’s temperature with the precision of a slow, sewing-machine needle” – Nicola Chester

The presence of Woodcock on the Red List causes heated debate; how can this still be a game species? Red-listing is indisputable; the latest survey by BTO & GWCT showed that there was a decline in roding males from 78,000 in 2003 to 55,000 in 2013, with the species being lost from yet more areas of the UK. Each autumn, the number of Woodcock in the UK rises massively, with an influx of up to 1.4 million birds. Annual numbers depend upon seasonal productivity and conditions on the other side of the North Sea. A recent report on breeding wader numbers in Norway, Sweden and Finland, shows that breeding populations of Woodcock in this area are not declining (Fennoscandian wader factory).

The UK’s breeding Woodcock population is under severe threat from things such as increased deer browsing and drier ground conditions but winter numbers appear to be stable. The difference in conservation status between breeding and wintering populations is reflected in the fact that Woodcock is on both the Red List and the Quarry List, for now. There is a WaderTales blog (Conserving British-breeding Woodcock) that discusses ways to minimizes hunting effects on British birds. These guidelines from GWCT emphasise the importance of reducing current pressures on British birds.

In conclusion

blog bookThe Red List creates some strange bedfellows. In the book, Turtle Dove follows Herring Gull; a bird with links to love and romance and another with at best the charm of a roguish pirate. But the List works; it creates an evidence-base that help those who devise agricultural subsidy systems, advise on planning applications, license bird control and prioritise conservation initiatives.

Red67 seeks to raise awareness of the UK’s most at-risk bird species, nine of which are waders, and to raise money for BTO and RSPB scientists to carry out important research. It’s a lovely book that captures the thoughts and images of a generation of writers and artists. You can learn more about the project, order the book and buy some Red Sixty Seven products by clicking here.


GFA in IcelandGraham (@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.