Wetland Bird Survey still going strong after 70 years

Knot PIC: BTO/Mike Dawson (Image: Archant)

Jointly funded by the British Trust for Ornithology (BTO), RSPB and the Joint Nature Conservation Committee (JNCC), in association with WWT, the latest WeBS report, Waterbirds in the UK 2016/17, released last week, reports on 110 waterbird populations and underlines the importance of the UK for millions of migratory waterbirds which spend the winter here or pass through on their way to their breeding grounds in the north and east.

Beginning as the National Wildfowl Counts in the winter of 1947/48, in response to apparent declines in the numbers of ducks and geese, 70 years later the scheme has expanded to include all wintering waterbirds, counted every month by 3,000 volunteers around the UK.

Habitat creation or climate change has helped species such as little egret, avocet and bittern increase. The report says breeding bitterns in the UK have shown “a strong recovery in the past 15 years” with a minimum of 166 booming males recorded over 62 sites. Much of this increase has been on sites that were created in the mid 1990s, such as Lakenheath Fen in Suffolk and Ham Wall in Somerset.

Introduced species, Canada goose, Mandarin duck and Egyptian goose, are also all becoming more common with increases over the last 10 years of 12%, 43% and 128% respectively.

However, many species of wader that feed in the UK’s estuaries in winter are declining, according to the latest findings: ringed plover, for example, are wintering in just half the numbers that used to spend the winter here 25 years ago.

Wintering curlew are also down - by 21%; this is a species for which other surveys have detected worrying breeding declines.

There is more of a mixed picture for duck species that use inland water bodies - over the past quarter century teal have increased by 40% and shoveler by 80%, but mallard has decreased by 38% and pochard by 69%.

WeBS national organiser at BTO, Teresa Frost, said, “Findings showed that during the winter of 2016-17 counts of migratory ducks and waders were slightly higher than we would have expected from recent trends. We think this was related to cold weather on the continent encouraging some birds to move to the UK, where the weather was very mild.

“Even though climate change means some species are typically wintering further north-east in Europe than they used to, it shows the importance of our wetlands as a refuge in severe weather conditions.”

Understanding the status of waterbird species is vital to help guide conservation action: the BTO says waterbird counts from WeBS have long been the cornerstone of UK policy and protection for wetland birds, from informing wetland management and wildfowling consents, to identifying important areas for designation as protected sites.

The most important protected sites for birds in the UK are part of the Special Protection Area (SPA) network, and many SPA sites have been designated on the basis of the large numbers of waterbirds recorded there through WeBS surveys.

A recent review found that over a third of the UK’s non-breeding waterbirds use the UK SPA network, particularly species that flock together in winter at high densities. As well as WeBS counts being used to inform site designation, the ongoing counts are invaluable for monitoring how species are faring on these sites, and so how successful the protected site network is.

SPA sites include Abberton Reservoir and the Blackwater and Colne Estuaries in north Essex, and the Alde-Ore Estuary, Breckland, the Deben Estuary, Minsmere-Walberswick and the Stour-Orwell Estuary in Suffolk.

In terms of numbers of birds supported, the top Suffolk sites are: the Stour Estuary, which saw a total of 42,780 birds of a variety of species winter at its location; the Alde Estuary (29,810), the Deben Estuary (18,994), Orwell Estuary (18,084) and Blyth Estuary (7,214).

These include internationally important numbers of knot on the Stour (11,398) and avocet on the Alde (1,351).

n Go to www.bto.org/wituk for full report