The study of the British coast shows changes in the wintering waterfowl populations

The results of a survey of wintering waterfowl on the UK’s non-estuarine coast, carried out by a network of volunteer observers, revealed significant changes in the numbers of several waterfowl species, including the lapwing, curlew, redshank, turnstone and sanderling.

The UK’s wetlands, estuaries and non-estuarine coastlines are of international importance to the number of non-breeding waterfowl they support. While long-term, voluntary surveys provide the valuable information needed by the waterfowl that use these sites annually, this data is most complete for our wetlands and estuaries. We know that the 17,000 km long coastline with no estuary is also important but cannot be covered annually. Because of this, regular surveys of the non-estuary coast are needed to get a full picture of these important waterfowl sites.

During the winter of 2015-16, volunteers explored around 9,183 km of coastline outside the estuary (53% of the total length), with most of this incredible effort (around 5,699 km) being done in Scotland. From this data, researchers at the British Trust for Ornithology (BTO) were able to compute measurements of the abundance and distribution of waterfowl and show the importance of this habitat for wintering populations of oyster, curlew, curlew, dunlin and redshank.

Sanderling, Copyright Glyn Sellors, from the Surfbirds Galleries

In absolute terms, Scotland has consistently supported the majority of the population in all non-estuarine waterfowl surveys for oystercatchers, ringed plovers, golden plovers, lapwing, purple sandpiper, snipe, curlew, redshank and turnstone. While this likely reflects the relative length of the coastline for Scotland (12,714 km) compared to England (2,705 km), Wales (1,185 km) and Northern Ireland (328 km), Purple Sandpiper, Curlew, Redshank and Turnstone still seem to be showing a tendency towards Scotland.

The survey also found that oystercatcher densities were higher in Wales than in England, Scotland or Northern Ireland. In Wales and other western parts of the UK, there is a greater proportion of overwintering oystercatchers from the Icelandic and Faroese breeding populations.

Results from Northern Ireland were published together with the Republic of Ireland in 2017. Northern Ireland is particularly important for the golden plover, lapwing, redshank, turnstone and purple sandpiper in a pan-Irish context as it holds a third or more of the non-estuarine sums.

Although smaller in absolute terms than Scotland, the densities of ringed plover and sanderling were highest in England. / Gray Plover Winter in greater numbers towards the south east of the UK, and the numbers were highest in England.

The survey also found that four species showed a significant decrease in frequency: lapwing (-57%), curlew (-31%), redshank (-37%) and turnstone (-325), only sanderling (+ 79 %)) seem to have increased since the last survey in 2007/08.

Dr. Teresa Frost, co-author of the report and organizer of the Wetland Bird Survey (WeBS), commented: “The overwintering populations of many of these species are from different breeds, often breeding in different parts of the world, and their relative distribution across the UK is only partially understood . It is important to be able to conduct regular surveys on the coast outside the estuary to not only complete the picture of the total number of wintering waterfowl, but also to highlight the changing fates of birds, which may come from different populations found in ours Wetlands and overwintering estuaries that are normally covered by the WeBS system. “

Teresa continued: “Curlew, for example, is a conservationist who is worried. We know from NEWS that around a third of the British curlew use the coast without an estuary. This survey showed that the non-estuarine population declined faster than the estuarine population in winter, and it is likely that many of these open-coast birds originated from the UK breeding population that we know are in trouble. “

Commenting on the survey, Teresa said: “Hundreds of citizen scientists walked along the coast and recorded the birds they found there, from the cliffs at Lands’ End to secluded beaches in the Shetland Islands. Some groups of volunteers traveled hundreds of miles to cover parts of western Scotland and they all walked a lot – each stretch was about 2 km and once you walked in one direction you had to go back in often stormy winter weather! We are very grateful to everyone involved. “

The surveys of the coasts not related to the estuary were carried out approximately every 8-10 years. More regular monitoring could provide better early warning of changes in locations outside the estuary, as well as the impact of changing the management of these locations, such as B. determine the establishment of naval defenses. The frequency of such monitoring will depend on the generosity of the many hundreds of volunteers who take the time to visit these sites during the sometimes challenging winter months.

Estimates of all habitat abundance of 13 species of waders wintering on the non-estuary coast of the UK and its member countries, UK and crown dependencies for NEWS III (2015/16). Each population estimate is presented as the bootstrap mean and its 95% confidence limits.

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