The Shetland Bird Survey: Population trends for widespead breeding birds 2002-2019

The BTO/JNCC/RSPB Breeding Bird Survey (BBS) is a vital scheme for monitoring population trends of common and widespread species across the UK, with the data used for a wide-range of purposes, from providing an indication of the state of our environment to playing an important role in understanding the reasons behind changes in trends.

Data from BBS also highlights variation in the population trends of some species across different regions of the UK, for example Willow Warblers, which are faring relatively well in Scotland but have seen large declines in the south of England. Because BBS is designed to deliver robust and representative information at a broad geographical scale, the state of bird populations in a smaller region subject to its own drivers of change may require bespoke information such as more intensive local survey coverage.

To address the lack of enough data on common breeding birds across the isles, the Shetland Breeding Bird Survey (SBBS) was established in 2002 by the Shetland Biological Records Centre, part of Shetland Amenity Trust. Although the survey methods are comparable to BBS, in SBBS there are differences, including that 1-km squares are self-selected by the volunteer surveyors. In the 18 years since 2002, an impressive 145 1-km squares spread across the isles have been surveyed, allowing Shetland population trends for 12 common breeding passerine and wader species to be estimated for the first time.

SBBS data collected by volunteers between 2002 and 2019 has revealed that Oystercatcher, Lapwing and Redshank populations have declined at a similar rate to elsewhere in the UK. However, for Curlew no population change was detected in Shetland in contrast to the declines observed in this species in Scotland and the UK as a whole. Similarly, for passerines, declines of Skylark and Wheatear in Shetland were comparable to declines observed across the rest of the UK. However, there was better news for Starling and House Sparrow populations, which have both increased on the isles in contrast to declines at the UK level.

Thanks to SBBS volunteers, this improved understanding of local population changes can help enhance local conservation decisions and management on Shetland, as well as providing valuable information to better understand variation in population trends among different regions of the UK.