Every year the British Trust for Ornithology (BTO), on behalf of a cluster of conservation bodies – the Joint Nature Conservation Committee, the RSPB and the Wildfowl and Wetlands Trust – organizes the Wetland Bird Survey, which is the principal scheme for monitoring the UK’s wintering waterbird populations. The scheme involves thousands of observers, mainly volunteers (3,290 last year), who make counts of water birds once a month at a wetland in their area. The BTO has just published the attractively illustrated 38th WeBS Annual Report, which covers the period from July 2018 to June 2019, when 5,145 sectors were visited, and 39,617 count visits were made, 71% in the core September – March period. The main emphasis of the report is thus on wintering, rather than on breeding, birds.
Full details of the data for the year are available at www.bto.org/webs-reporting . The present note highlights some of findings relating to wintering Curlews in the United Kingdom in 2018/19, a mild and dry winter, but with a colder period in late January and the beginning of February. January 2019 was the only month with significant ice cover (6.8% of sites, mainly in eastern Britain). The concise summary of national trends makes special reference to Curlew, noting that the Curlew index increased compared to the previous winter, but that the 25-year trend worsened to -33%. This is illustrated by a photo of a Curlew in flight on page 11. Table One shows the 25-year trend (from 1992/93 to 2017/18) – a decrease of 33% in wintering Curlews; it also shows the ten-year trend (from 2007/08 to 2017/18) – a slightly less severe decrease of 21%. Table 2 gives figures for these trends in the four constituent countries: all four show a decrease over the 25 years, most severe (42%) in Wales, 34% in England, and 28% in both Scotland and Northern Ireland.
The report also discusses ‘Species threshold levels’. These are the numbers used to identify sites of international and national importance, based on criteria adopted under the Ramsar International Convention on Wetlands in 1988, and later adopted for the European Union Bird Directive. Any site holding 1% of the total international population of a species, subspecies or population is considered to be of international importance, while any site holding 1% of the estimated British numbers is considered to be of national importance. For a species whose numbers are decreasing, the 1% figure will obviously drop, and this is what is happening with Curlew. The international threshold has dropped from 8,400 to 7,600, so that a site will now be considered of international importance if it holds 7,600 Curlews. Similarly the GB threshold for national importance has dropped from 1,400 to 1,200, while the All-Ireland threshold remains at 350.
The 2018/19 report contains a host of other fascinating articles and tables, relating to waterbirds other than Curlews, among them ‘Climate impacts on waterbirds’ and how Lapwings go about ‘Escaping the cold’; all this even without delving into the detailed counts for your area, available online. But the watchword for Curlew remains “Attention!”. We know that numbers of lowland breeding Curlews are declining, but so are numbers of the Curlews that breed in continental northwest Europe and come to winter in the British Isles.