Aerial surveys in Carmarthen Bay SPA get common scoter in focus
APEM have completed new high-resolution aerial surveys of birds and marine mammals in Carmarthen Bay special protection area on behalf of Natural Resources Wales.
The surveys were carried out in December last year and February this year, with the data collected from thousands of ultra-high resolution aerial photographs used to assess the numbers and distribution of both birds and marine mammals.
Species can be identified with very high precision thanks to the detail captured in the high-resolution images. Of particular interest is the number and distribution of common scoters, which overwinter in the area in their tens of thousands.
Carmarthen Bay SPA was the first fully marine SPA in the UK and was designated in 2003 solely for wintering common scoter, a species of marine sea duck that is currently included on the Red List of threatened species.
APEM’s survey results from December 2016 produced a population estimate of 35,211 common scoter within Carmarthen Bay special protection area (SPA).
Peak abundance last winter is likely to have occurred in February when our survey produced a population estimate of 36,314.
Natural Resources Wales uses the data gathered on the birds and marine mammals within the special protection area to help manage it and to report on its condition.
APEM ornithologist, Helena Voet, said:
It’s typically quite hard to get accurate population estimates for common scoter because they tend to be quite widely dispersed in large, irregular aggregations.
But aerial surveys using our state-of-the-art digital camera systems give us the data that Natural Resources Wales needs in order to properly manage the site.
An irregular grid pattern of flights was used for the aerial surveys, capturing around 22 percent of the SPA. By carefully designing the survey and analyzing the resulting images APEM’s scientists are able to model the numbers and distribution of both common scoter and other species.
APEM also surveyed the area in the winter of 2012 to 2013. One aerial survey and two ground-based surveys showed how the number of common scoter rose and fell during February. Estimated numbers fell from over 30,000 to less than 14,000 in less than a week.
As well as common scoter, other species identified in Carmarthen Bay SPA are mainly gulls, waders and several marine mammals.
Photo credit: Common scoter (resized) by Marton Berntsen licensed under CC BY 4.0
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