The 40th Wetland Bird Survey (WeBS) report, for 2021/2022, has just been published. WeBS is the principal scheme for monitoring the populations of the UK's wintering waterbirds, providing an important indicator of the status of waterbird populations and the health of wetlands. Today’s blog by Simon Wotton, Senior Conservation Scientist, gives an update on the latest results.
The 2021/22 report focuses particularly on migratory species that link us with Iceland, Greenland and eastern Canada. With Highly Pathogenic Avian Influenza (HPAI) having had worrying impacts on waterbirds, seabirds and domestic birds over the past two years, this migratory route has been highlighted as a possible pathway for how the latest H5N1 virus strain reached the Americas.
Pintail trends for the last ten years appear to be stable, but 25-year trend is still down by 28% (c) Ben Hall (rspb-images.com)
Waterbirds in the UK has always included summary results from the Goose & Swan Monitoring Programme (GSMP), but with recent changes to the partnership, this report is now the primary reporting mechanism for GSMP results. This includes the Icelandic-breeding Goose Census and Age Assessments, as well as bringing together results for special surveys and surveys led by other groups. The 2021/22 GSMP field season was coordinated by WWT and the reporting and analysis was led by JNCC.
2021/22 summary
WeBS aims to assess the size of waterbird populations, determine trends in numbers and distribution, and assess the importance of individual sites. The 2021/22 report documents waterbird counts at 3,326 sites across the UK, surveyed by 3,694 WeBS counters.
Many of the sites monitored under WeBS are of international importance and designated as Ramsar Sites and Special Protection Areas (SPAs), including the four principal WeBS sites over the past five years: The Wash, Ribble Estuary, Morecambe Bay and Dee Estuary. The Wash remains the most important site for wintering waterbirds in the UK, with 402,663 birds counted in 2021/22 (400,173 in 2019/20), followed by the Ribble Estuary with 227,776 waterbirds counted (202,706 in 2019/20).
The winter of 2021/22 was the UK’s eighth mildest recorded, with December starting off cold, but then becoming milder with few frosts and average rainfall. January was dry, but February was unsettled with frequent rain and a stormy period in the week up to and including the WeBS Core Count date. Despite some cold nights in January in England and Wales, the overall temperatures for December, January, and February were above the long-term average, with the monthly mean temperatures 1.1, 0.8 and 1.5 degrees celsius above average respectively. December temperatures in the Baltic were cold, with a marked contrast between the north-east of Europe with the mild conditions in the south and west of the continent; but as the winter continued, the north-east became warmer than average.
Species trends
Bewick’s Swan (10-year trend -90%) saw another record low index value in 2021/22 but Whooper Swan (10-year trend +27%) reached another high. The Greenland (10-year trend +24%) and Svalbard (10- year trend +10%) Barnacle Goose populations are known to have had significant avian influenza mortality events and continued monitoring will be essential to see if there are population level impacts.
Twelve of the duck species reported on by WeBS have declining 10-year trends, with increases for only Mandarin Duck and Shoveler, which reached a record high. The Pintail 10-year trend is now stable, but the 25-year trend is still down by 28%. The indices for Pochard (10-year trend -39%) and Mallard (10-year trend -22%) again reached record lows as did Smew (10-year trend -77%).
Ten-year trends were mixed for waders, with positive values for Avocet, Black-tailed Godwit, Golden Plover, Knot and Sanderling. Conversely, Bar-tailed Godwit, Curlew, Purple Sandpiper, Oystercatcher, Grey Plover and Ringed Plover all had declines of 10% or more over the decade. The Bar-tailed Godwit (10-year trend -30%) index was a record low; this index has historically shown large fluctuations but in recent years has shown a small, steady decline. The Sanderling (10-year trend +7%) index was a record high.
Coot on nest (c) Ben Andrew (rspb-images.com)
Declines continued for Coot (10-year trend -27%) and Red-necked Grebe (10-year trend -20%) which both saw record low index values. Egrets continued to do well with record highs for Little Egret (10-year trend +59%), Cattle Egret and Great White Egret.
Partners
The survey is run by the British Trust for Ornithology (BTO), in a partnership between the BTO, the Joint Nature Conservation Committee (JNCC) and RSPB. Whilst the focus of this report is the July 2021 – June 2022 WeBS year, the WeBS Report Online has also been updated in this report with site peak count data for the 2020/21 WeBS year.
It was not analytically possible to produce statistics for the 2020/21 dataset as usual. In place of the usual report, a newsletter, WeBS News 2020/21 Special Edition, was published in June 2022, containing a report on a simulation study of the impacts COVID-19 restrictions in early 2021 had on the usual WeBS indices and trends.
Detailed data on WeBS sites and species are available through the BTO WeBS interactive website. A copy of the 2021/22 report can be downloaded here.
For more information contact Simon Wotton, Senior Conservation Scientist, or Vanessa Amaral-Rogers, Senior Science Communications Executive, or follow us on Twitter @RSPBScience #WeBS #wetlandbirds.
Continue reading
Would you like to be kept up to date with our latest science news? Email with the heading 'enewsletter' to be added to our quarterly enewsletter.
Want our blogs emailed to you automatically? Click the cog in the top right of this page and select 'turn blog notifications on' (if you have an RSPB blog account) or 'subscribe by email'.