The latest blog from Simon Wotton, RSPB’s Senior Conservation Scientist, is looking at the latest survey data for our waterbirds and what this means for some species.

The 38th Wetland Bird Survey (WeBS) report for 2018/19 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.

The survey is run by the British Trust for Ornithology (BTO), in a partnership between the BTO, RSPB and the Joint Nature Conservation Committee, in association with the Wildfowl & Wetlands Trust.

The latest report was conducted by 3,290 dedicated counters, across 2,846 wetlands across the UK. WeBS aims to assess the size of waterbird populations, determine trends in numbers and distribution, and assess the importance of individual sites.

Which are the best sites?

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, the Ribble Estuary, Morecambe Bay and Thames Estuary. 

Pink-footed goose, flock in flight across the Ribble Estuary (c) Andy Hay (rspb-images.com)

The Wash remains the most important site for wintering waterbirds throughout the whole of the UK, with 417,911 birds counted in 2018/19 (382,523 in 2017/18).

Morecambe Bay comes next with 207,627 waterbirds counted (182,017 in 2017/18). Although 2018/19 was generally a mild and dry winter, counts were generally higher than in 2017/18 and similar to the high counts in 2016/17 that were caused by the cold weather in Central Europe.

Species changes and fluctuation  

Pink-footed goose and the three Barnacle goose populations continued to increase, but Dark-bellied brent goose showed a slight decline. Canada Goose numbers reached a record high. Whooper Swan attained its highest ever index again in 2018/19, but Bewick’s swan remains at historically low levels.

The 2018/19 index value for Wigeon was notably low, although the 25-year trend is +12%: this is likely to be weather-related, with the population staying for a shorter time in the UK. Shelduck is showing signs of recovery, with the index value at its highest level since 2010/11.

Female Goldeneye at Martin Mere, Wildfowl and Wetlands Trust (c) Ben Hall (rspb-images.com)

Mallard, Pochard, Goldeneye and Red-breasted merganser all had slightly higher index values than in 2017/18, but their 25-year trends are -35%, -69%, -62% and -42% respectively.

Turnstone was at its lowest ever index value, just below that of 1974/75. Knot numbers were also low, with the index at its lowest level since 1982/83. The Curlew index increased compared to 2017/18 but the 25-year trend worsened, to -33%. Purple sandpiper showed a slight recovery, although its 25-year trend is -50%. Avocet and Black-tailed Godwit continue to show strong long-term population increases.

Assessment on protected sites

The 2018/19 report also includes a summary of the latest WeBS Alerts assessment that was published in autumn 2019. WeBS Alerts use WeBS data to assess the performance of protected sites that have one or more non-breeding waterbird ‘features’.

WeBS Alerts assessed change for 474 site-species populations on 84 Special Protection Areas. For the first time, assessments were carried out for 206 Sites of Special Scientific Interest in Great Britain and 18 Areas of Special Scientific Interest in Northern Ireland.

Protected sites are incredibly important for waterbirds like this Pochard (c) Ben Hall (rspb-images.com)

As an example, Pochard numbers on protected sites have declined at a comparatively slower rate than for the whole of Great Britain: protected sites now hold 40% of the British wintering Pochard population compared to just 15% in the 1970s and 1980s. In Northern Ireland, almost no Pochards now occur outside protected areas

Detailed data on WeBS sites and species are available through the BTO WeBS interactive website.

The full report can be found here.

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.

Anonymous