Curlew expert and Curlew Action trustee Mike Smart shares an update on colour-ringed Curlew sightings from his local patch on the Usk, how colour-ringing is helping ornithologists to understand Curlew movements, and requests sightings and photographs of colour-ringed Curlews on the Usk.
Current status of Eurasian Curlew
A British Birds article in 2015 [PDF available via Curlew Forum] suggested that Eurasian Curlew was the highest bird conservation priority in the UK, for the following reasons:
- the drastic decline in its global numbers (caused by habitat loss, nest predation and poor chick productivity),
- 25% of the world population (just under 60,000 pairs) breed in UK;
- another 25% of the world population comes from northwest Europe to winter in UK.
Over the last ten years, a large number of Curlew research projects have developed, and many conservation bodies (notably Curlew Action) have devoted increasing attention to Curlews. It is chilling to reflect that, of the eight species of Curlew in the world, two (Eskimo and Slender-billed Curlew) are thought to have become extinct in the last thirty years.
Ringing operations on the Usk in 2015/16
In winter 2015/16, as part of an investigation into the possible effects of building tidal lagoons in the Severn estuary, 41 Curlews were caught in a British Trust for Ornithology (BTO) and Wildfowl and Wetlands Trust (WWT) project during cannon-netting sessions, the first at Newton Farm, inland of Peterstone (near Rhumney Great Wharf, hence strictly speaking on the Severn estuary), the second near the West Usk lighthouse at St Brides.
All were adults, there was not a single juvenile among them, a typical finding of Curlew studies; worryingly few juveniles are found in Curlew flocks wintering round UK coastlines. Some were marked with electronic tagging devices, which are designed to fall off later in the year when the birds moult.
They were also marked with one metal and five colour rings; all 41 were marked with two coloured rings, always Orange over White, on the left tarsus (below the “knee”) as a marker; these marker rings are often difficult to see, especially if the bird is standing in vegetation or shallow water.
The other three colour rings, one on the left tibia and two on the right tibia (above the ”knee”), varied from individual to individual; the colours used were: Orange (O), White (W), Black (N), Green (G), Blue (B) and Red (R). The rings did not carry any inscription, whether numbers or letters. To identify an individual, it is therefore crucial to record the colours of the single ring on the left tibia AND the two rings on the right tibia.
Another reading problem arises because Curlews often stand on one leg, particularly in high tide roosts. One of the 41 (Black on the left tibia, Black over Orange on the right tibia, hence NNO), was already carrying a metal ring when caught in January 2016; it had been ringed as an adult on the nearby Taff estuary, Cardiff, on 16 January 1997, and must therefore have been born in 1994 or before and was at least 22 years old in 2016; the oldest known Curlew (from recoveries of metal rings on the BTO website) is 32 years and seven months, a record established as long ago as 2011.
During the rest of the 2015/16 winter the BTO/WWT project team followed the movements of tagged and colour-ringed birds. After summer 2016 however, the monitoring effort decreased, and there were few records of colour-ringed Curlews on the Usk.
Meanwhile, further up the Severn estuary, another BTO Curlew colour ringing project had been operating in Gloucestershire. Between 2010 and 2013, 165 Curlews had been cannon-netted and colour-ringed on the foreshore between Chepstow and Lydney, in an area where at that time up to 1,000 Curlews wintered, though numbers have decreased at present to around the 500 mark.
Intensive observations of these birds, largely by John Sanders, had demonstrated that these birds were extremely site-faithful, returning year after year to the same wintering ground, and not moving on at all from this wintering ground to other wintering areas: of the 165, only a single bird was on one occasion shown to move on to another wintering area (in Cornwall), and even this bird moved back through the normal Severn wintering ground on its northward spring migration later in the same winter.
Summer observations of the 165 birds showed them equally site-faithful to breeding sites, spread over a broad compass, some nearby in the upper Severn Vale, some in Yorkshire or East Anglia, some in the Low Countries (Netherlands and Rhineland Germany), and a good proportion far to the north-east in Finland and Sweden. John has written a number of papers based on his findings, demonstrating site fidelity, early return to wintering areas, and high survival rates of adults.
In view of these results from the Gloucestershire project, it seemed a shame that little or no serious effort had been made to monitor the birds ringed on the Usk in 2015/16. From winter 2019/20 therefore Chris Wells and I (with the valued help of National Nature Reserve staff and Gwent Ornithological Society members) have been recording colour-ringed Curlews on the Usk estuary.
It is important to note here that the so-called “winter” period runs from the second week of June (when the first Curlews return from their breeding grounds to moult on the coast) until the third week of April (when the last wintering Curlews depart for breeding areas to the north-east).
GOS members will know that it is difficult to observe Curlews on the Usk estuary. They feed on the mudflats at low tide, and on most high tides move to Nash foreshore, where it is difficult to approach them. Only on the very highest tides (usually above 12.5 metres at Newport) do they come to high tide roosts at Peterstone Wentlooge, St Brides or Goldcliff Lagoons, where there is a chance of reading the rings accurately, and even then, the vagaries of tide, wind and light can make observation difficult; at Goldcliff high water levels sometimes mean that the Curlews’ legs are under water, making ring reading impossible.
Nevertheless, some interesting data have been collected and details are given in the rest of this note. A number of interesting questions on Usk wintering Curlews remain unanswered: some undoubtedly move as far upstream as Collister Pill; data from the 2015/16 study indicate that Peterstone ringed birds move as far downstream as Cardiff Bay, but there are few recent observations from the Cardiff area. And what is the size of the total Usk wintering Curlew population? Observations this year suggest at least a thousand; coordinated Curlew counts at high tide would be of the greatest interest.
Winter observations on the Usk of Curlews colour-ringed in 2015/16
Most of the 2015/16 cohort were followed during 2016 until their tags fell off, but there were few records of colour ringed birds until 2019, and some ‘disappeared’ for up to five years. In the first two winters of our observations on the Usk, 2019/20 and 2020/21, 32 of the original 41 colour-ringed birds were re-sighted; in addition to these 32 birds, a further four birds were seen in winter 2021/22, so that 36 of the 41 birds ringed in 2015/16 must have been alive at the end of the 2020/21 winter, indicating a very high adult survival rate.
In winter 2021/22, 33 of the original 41 were re-sighted; numbers observed in 2022/23 and 2023/24 were rather lower at 23 and 20 respectively, largely because high water levels at Goldcliff made observation there very difficult.
In these two winters most of the observations were made at Peterstone by Chris Wells. It is very notable that birds originally ringed at Rhumney, near Peterstone, occur overwhelmingly at the Peterstone roost, thus demonstrating fidelity not just to the Usk estuary, but to one particular sector. So far (to the end of August 2024) this ‘winter’, nine have been recorded, all at Peterstone or St Brides. NNO (the one marked with a metal ring at Rhumney in 1997) was last observed on 30 August 2022.
As in the Gloucestershire survey, there are vanishingly few observations of Usk-ringed Curlews at other wintering sites. One male, Orange White Red (OWR) has twice been observed at WWT Llanelli - from August to October 2019 and again in September 2020; but in 2020 he returned later in the winter to the Usk estuary, and in subsequent winters he has been observed in late winter on the Usk. It seems that he moults at Llanelli, only to return later in the winter to the Usk.
Three other Usk-ringed birds have been recorded elsewhere in the UK, two of them, it would seem, on their way between the Usk and breeding grounds elsewhere: female Black Blue Orange (NBO) was seen at the Gloucestershire project site on 19 April 2016, no doubt on her way to some northeastern breeding ground; Orange Orange Black (OON), probably a female, was seen at Chew Valley Lake near Bristol on 7 July 2023, presumably on a short stopover, since she was back on the Usk from 3 August onwards. A third Usk-ringed bird (Black Orange Green, NOG, a male) has appeared in two different years at Alston Reservoir in Lancashire - in late March 2019 and 2021; Lancashire observers think he may be on a stopover on a journey further north, but he could be breeding on the moorlands above Preston.
Observations of Usk-ringed Curlews on their breeding grounds
In addition to NOG which may be breeding in Lancashire, reports from the nesting grounds of three of the 41 Usk-ringed Curlews are available, all (as would be expected from other breeding records of British-ringed Curlews) in a north-easterly direction and all in Baltic lands - Poland, Sweden and Finland.
The star bird is undoubtedly male Black White Orange (NWO) which was reported from Trzyrzecze (53.31N 23.04E) in Poland by Dominik Krupiński from the excellent Polish breeding study in April 2018, then again in April 2019; it was back on the Usk in October 2019, and in Poland again in April 2020, the last sighting of this bird. The sighting in Poland in April 2018 was only the third ever recovery of a Curlew moving between Poland and UK, and the two earlier ones had been of migrants moving along the Baltic, not of birds definitely breeding in Poland. Since 2018 there have been numerous additional ringing recoveries of birds moving between UK and Poland, but NWO blazed a trail which has only become more familiar in the last five years.
The second Usk-ringed Curlew to have revealed its breeding place is female Black White Green (NWG), recorded twice in June 2016 at Lindänget, Orsa (61.04N 13.47E), northwest of Stockholm in Sweden, and reported back on the Usk every winter from 2019/20 to 2023/24 (latest sighting on 14 February 2024, though not yet this ‘winter’).
The third Usk bird with a known breeding site is Black Red Black (NRN) reported nesting at Viinikantie, on the island of Hailuoto, Oulu province (65.01N 24.43E) in Finland (where a large proportion of British wintering Curlews nest), then on the Usk in September 2020 and February 2021, and from August to November 2021, the most recent sightings.
Colour-ringed Curlews from other ringing systems on the Usk
Of course, birds ringed locally are not the only colour-ringed Curlews noted on the Usk. Birds ringed elsewhere in UK occur, as well as birds ringed on the European continent.
Among continental birds are two from Poland, both ringed with yellow inscribed flag rings by the Polish Curlew project which has been running for ten years now. R29 was released on 22 July 2019 in the Notec River valley (52.54N 16.27E) and was seen by Chris Wells at Peterstone thirteen times in different winters, the first observation on 17 October 2020, the most recent on 15 January 2023. T32 was released on 20 July 2022 in eastern Poland, in the Zelizna grasslands (51.52N 22.45E) and was noted by Chris at Peterstone on 14 January 2024, the first resighting since ringing; it has already returned to Peterstone in August 2024.
Very significantly, both Polish Curlews were head-startedWhat is headstarting and how does it help curlews? birds, i.e. birds raised in an aviary from wild-taken eggs and released in the wild once able to fly, a technique developed to increase the number of fledged chicks. Neither of these two birds has, as yet, been resighted back on the Polish breeding grounds.
Two birds of German origin, released in the lower Rhine Valley, have been sighted on the Usk. One was a head-start, the other a breeding male ringed in 2012 (which has nested every year since then in the same area) and sighted at Goldcliff in different winters (August/September 2019, August 2020, again in 2021/22 and 2023/24) – a bird truly showing site fidelity to both summering and wintering areas.
Colour-ringed Curlews from other British-based projects have also been observed: two birds that nest in East Anglia have been seen by Chris Wells at Peterstone, one in winter 2023/24 and already again in 2024/25, another illustration of site fidelity. Birds ringed by Tony Cross’ Mid-Wales Ringing Group have also been recorded, two ringed at a spring/summer roost at Caersws in the headwaters of the Severn, two on their breeding grounds in the Wye Valley in Herefordshire (both the latter also carry satellite tags).
Nearer home, Curlews from a WWT project in the Severn Vale have also been recorded: one (yellow flag AX) breeds in the Severn vale above Gloucester; two others are head-started birds, raised and released at Slimbridge in 2019. The eggs were taken from East Anglian airfields, where they would otherwise have been destroyed to prevent airstrikes, and the 50 young birds thus raised were released at Slimbridge; at least five of the 50 are now breeding in the upper Severn Vale, and two (numbers 49 and 50) have been recorded in winter at Goldcliff – even though the white rings are very small and very difficult to read. It is not yet known whether or where these two head-started youngsters are breeding.
Future plans
The detailed records of colour-ringed Curlews from the Usk are submitted regularly to BTO Cymru, as a contribution to their studies of the species’ survival and movements. Information on the origin of all colour-ringed birds (not just Curlews) is available on the European colour ringing website.
It is planned to continue the search for colour-ringed Curlews in the Usk estuary. We hope that this article will be of interest to bird-watchers visiting the area and will encourage them to look out for colour rings on Curlews (and for that matter other species). We would be particularly grateful for photographs of any colour-ringed birds. Please send observations and photographs to smartmike143@gmail.com .
Those interested in wider aspects of Curlew conservation may like to consult the Curlew Action website which gives details of the charity’s activities (including its many webinars, past, present and future) and of how to make donations.
Note from Curlew Action:
We are currently fundraising to run an Online European Headstarting Workshop in early 2025. Following the success of our European Curlew Fieldworker Workshop in Norfolk in February 2024, and our trips to various European countries, we feel that it is important to bring together conservationists from across Europe who are working on Curlew headstarting.
We have a campaign open with Aviva which means that any donation made will be matched by Aviva (up to £250) - effectively doubling your donation. You can find out more about the workshop, along with an appeal from Mary Colwell, on the Aviva website.