Sixty years of Wash waders

wwrg tt balance

Weighing a Turnstone

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

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

wwrg table

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

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

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

Firing box connected to 4 cannon-nets

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

wwrg oldies

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

Oystercatcher

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

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

Grey Plover

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

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

wwrg map GV KN

Knot

wash knot

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

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

  • We are still learning about Knot migration. The cluster of reports of WWRG-ringed birds in Northern Norway looks odd on this map projection but it turns out that this is a well-used stopping-off point for islandica Knot heading for northern Greenland and NE Canada. This route was first confirmed in 1985, when a joint Durham University and Tromsø University expedition caught 18 Wash-ringed birds in a total catch of 1703 birds.
  • wwrg net set

    Setting cannon-nets

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

  • The most recent analysis of wader populations in Great Britain showed that there was a drop of nearly 20% in wintering Knot numbers (from 320k to 260k) in less than a decade (see Do population estimates matter?). Regular catches on the Wash will help produce estimates of annual survival rates and age ratios of the islandica subspecies.

Sanderling

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

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

wwrg map SS DN

Dunlin

wash dunlin

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

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

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

Black-tailed Godwit

wash blackwit

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

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

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

Bar-tailed Godwit

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

wwrg barwit map etc

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

Curlew

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

wwrg curlew map etc

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

Redshank

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

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

wwrg map RK TT

Turnstone

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

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

A few more highlights

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

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

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

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

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

What do we know now?

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

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

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

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

Diamond Jubilee

PLI

Phil Ireland releasing a Curlew

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

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

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

wwrg sunset

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

Wee quiz:

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

 


GFA in Iceland

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

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Fewer Spotted Redshanks

blog stalkingIt’s usually a good day if you see a Spotted Redshank in Britain or Ireland. How about a flock of 60?

On 27 July 1975, I was fortunate to be part of a Wash Wader Ringing Group cannon-netting team that caught 60 Spotted Redshanks at Terrington, on the Lincolnshire border of Norfolk. When we fired the nets, we knew that there were some Spotted Redshanks in the catching area but, as these birds were part of a mixed catch of 414, most of which were Redshank and Dunlin, the total number of these elegant ‘shanks came as a very welcome surprise. Why so many, what did we learn about Spotted Redshanks and what do we know now?

How to catch Spotted Redshanks

blog water groupThe spring of 1975 was very wet in East Anglia, with twice the annual monthly rain as is normal in April. Pools formed in fields, seed failed to germinate and there were many bare patches in cereal crops. Rather than leave a muddy pool to bake in the summer sun, a tidy-minded Terrington farmer decided to cultivate a strip through the corner of one of his fields, very close to the sea-wall. Conveniently, he created an area that was just the right width in which to set cannon-nets, meaning that any birds that chose to roost on the bare part of the field over high-tide were almost bound to get caught. It is unlikely that we missed many other Spotted Redshanks when we caught our 60.

This was actually the second catching attempt on the site. Two weeks earlier, on the previous set of spring tides, we had caught 460 birds in two catches – mostly Dunlin and Redshank but with one Spotted Redshank. In the previous 15 years, WWRG had caught just two Spotted Redshanks but more than 4000 Redshanks. Across the whole of Britain & Ireland, between 1909 and 1974, a grand total of 169 Spotted Redshanks had been ringed, which again puts the figure of 60 into perspective.

Where did they go?

The Spotted Redshanks we see in Britain & Ireland are assumed to breed in boggy woodlands in northern Scandinavia and Russia but there are no recoveries of ringed birds to prove this. Prior to the Terrington catch, there had been two foreign recoveries of BTO-ringed birds. A bird caught in Essex in August 1963 was caught by a Dutch ringer in May 1967, presumably on spring passage. Another, caught in July 1966 in Kent, was shot in Malta in April 1968, on its way back from an unknown wintering location in Africa.

blog swimmingThere have been two foreign recoveries of the Terrington birds, caught on 27 July 1975; amazingly both were in Morocco. The first was shot in March 1976, perhaps on its way north, but the second, shot in January 1983, may well have been wintering in North Africa. There has been one other foreign recovery of a WWRG since 1975; a bird ringed by WWRG in August 1978 was shot in Italy in March 1979, presumably on spring migration. This was the only Spotted Redshank ringed by WWRG in 1978. Six Spotted Redshanks have been recovered in France since 1975.

According to the 2016 BTO Ringing Report, a total of four foreign-ringed birds have been found in the UK. Two Dutch birds have been found dead at Hayling Island, Hampshire (January) and Tetney Lock, Lincolnshire (January) and a third bird was present at Titchwell, Norfolk in the summers of 2013 and 2016, where the ring was read in the field. A bird ringed in Germany on 10 August 1972 was recaught by ringers at Eyebrook Reservoir, Rutland, 23 days later.

The Terrington-ringed bird shot in Morocco in 1983 still represents the BTO longevity record for the species (7 years 5 months 16 days); this is similar to records set by Finnish and Dutch ringed birds. (There is a WaderTales blog about longevity in waders here)

Summering Shanks?

Many of the Spotted Redshanks we caught on the Wash in 1975 were thought, at the time, to be summering, first-year birds but these were in the days before the publication of the Guide to the identification and ageing of Holarctic Waders (Prater, Marchant & Vuorinen, BTO) and I do wonder whether early onset of moult may have led to some ageing errors. We now know that females can moult very early, having left their partners to finish brooding their eggs and bring up the chicks. Some of their moult can take place near their breeding grounds, which could mean half-summer plumage birds arriving in July. Alternatively, birds could have arrived in June and already be in moult. Had the wader guide been available in 1975, we might have been able to separate out full-plumage males and females by looking at the central under-tail coverts and the edges of the head feathers. Next time …

blog BirdTrackThe latest BirdTrack graph gives pretty clear evidence that there is a gap between the end of spring migration and the start of autumn passage. However, as you can see, it’s short; just the end of May and the start of June. It has been suggested that not all first-year Spotted Redshanks travel to the breeding grounds, with some staying in their wintering grounds and others completing only part of the journey north. The few birds that are still in the UK in the May/June gap could be some of these one-year-old individuals or full adults not in condition to breed.

Looking at numbers

blog booksAs I prepared for this article, I turned to Twitter to see how unusual the Terrington catch had been, simply in terms of the number of birds counted in flocks. There have been some recent largish counts, including one of 52 at Old Hall Marshes (Essex) in September 2017 and 32 at Blacktoft Sands in Yorkshire in 2015 but, interestingly, I learnt that bigger flocks were mostly historical. According to the three books, The Birds of Norfolk, Suffolk & Essex, the three peak counts have been 187 at Snettisham in 1977, 112 at Minsmere in 1991 and 127 on the River Colne in 1972. Kent beat these East Anglian county records with a maximum of 220 at Grovehurst on 8 October 1972 (Birds of Kent, 1981).

This story from Northumbrian Birds illustrates a typical recent trend. Here, the record counts were of 27 and 21 at Lindisfarne in 1974 and 1976 but there has been a maximum count of just 7 in the last ten years. At the other end of England, Steve Rogers reported that he had 45 at Ruan Laniholme in Cornwall in 1977 but that “you’ll be lucky to see one” now. This is just a small selection of the comments received from a wide spread of  places, including Poole Harbour in Dorset and Cork in Ireland.

blog WeBSPotentially, the development of new nature reserves around the coast and along our river valleys might have created new opportunities for Spotted Redshanks, with birds spreading out across more sites and hence in lower concentrations? To get a national viewpoint, I turned to the online report from the monthly Wetland Bird Survey (WeBS). What did winter counts by volunteers from across the United Kingdom tell us about what has been happening to the species over the period since 1975? As you can see from the graph alongside, the index has dropped by 50% since the start of this century, in line with the local information for late-summer passage discussed above. (There is a WaderTales blog about WeBS here).

Conservation concerns

According to the BirdLife International species fact-sheet, as downloaded from http://www.birdlife.org on 25/07/2018, Spotted Redshanks are of ‘Least Concern’, largely because the large breeding and wintering ranges (map below) reduces the risk of extinction. Breeding numbers are hard to monitor, due to the low densities in the wooded marshes near the tundra edge, and the series of winter wader counts for the UK is much longer and more comprehensive than any other country in the wintering range. Perhaps there would be more concern if there were other international counts that showed the same sort of declines as seen in the UK?

blog birdlife map

BoCC4Here, Spotted Redshank is listed as amber, rather than green, simply because the estimated winter count of about 100 is large in a western European context. Perhaps a decline of 50% should create pressure to change amber to red or, more importantly, to revisit the ‘Least Concern’ designation. Whilst it might be hard to target conservation action at a species which uses such a wide range of breeding, passage and winter locations, perhaps we should acknowledge that, according to what is probably the best evidence available, we are seeing a rapid decline?

Our catch of 60 Spotted Redshanks in 1975 is an amazing memory but concentrations in these numbers could be found at a number of sites on the east coast between at least 1964 and the end of the 20th Century. For the moment, we must acknowledge that UK autumn flocks of 60 are largely a thing of the past. Perhaps flocks of 30 might soon be consigned to history? Keep counting!

blog three fly

 

 GFA in Iceland

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

@grahamfappleton