Assessing drivers of winter abundance change in Eurasian Curlews Numenius arquata in England and Wales. Issue 3 (3rd July 2021)

• Record Type: Journal Article
• Authors: Woodward, Ian D.; Austin, Graham E.; Boersch-Supan, Philipp H.; Thaxter, Chris B.; Burton, Niall H.K.
• Is Part Of: Bird study. Volume 68:Issue 3(2021)
• Page Start: 289
• Page End: 301
• Publication Date: 2021-07-03
• Subjects: Birds -- Ecology -- Great Britain -- Periodicals; Birds -- Conservation -- Great Britain -- Periodicals; Birds -- Ecology -- Periodicals; Birds -- Conservation -- Periodicals; Birds -- Great Britain -- Periodicals; Birds -- Geographical distribution -- Periodicals; Birds -- Counting -- Periodicals; 598.170941
• DOI: 10.1080/00063657.2022.2049205
• Languages: English
• ISSNs: 0006-3657

Abstract

ABSTRACT: Capsule: We assessed annual changes in Eurasian Curlew Numenius arquata wintering numbers at estuaries in England and Wales over 40 years against local and broadscale factors. Long-term trends likely reflect the cessation of hunting, but potentially also distributional changes associated with milder winters and changes in breeding success. Aims: To investigate whether local or broadscale factors might affect site-level annual abundance changes in Curlews in England and Wales. Methods: Relationships between Wetland Bird Survey (WeBS) counts from 46 estuaries from 1974/75 to 2016/17 and environmental data were assessed using Generalized Linear Mixed Models. Results: The winter abundance trend of Curlews in England and Wales closely matched the decline of breeding populations since the mid-1990s. However, there are clear differences in the trends prior to this. Our analysis suggests that winter counts were influenced by the cessation of hunting and by weather, with abundance decreasing during cold winters and increasing the following winter. The influence of severe weather was less pronounced in the immediate aftermath of the hunting ban. An increase in numbers in the east of the UK also occurred during this period. No effects were detected for other environmental variables, but this may reflect the fact that only static variation between sites was tested for these variables rather than change. Conclusion: The increase in wintering Curlew numbers in the UK during the 1980s and early 1990s likely reflects a positive response to the cessation of hunting, but also a wider redistribution associated with milder winters across the European wintering range. Winter temperatures influenced annual abundance changes at individual sites, although impacts on detectability are difficult to disentangle from impacts on survival using WeBS counts alone. Factors operating during the breeding season are likely to be the main drivers of the current population decline.