Digital video aerial surveys of Red-throated Diver in the Outer Thames Estuary SPA

Published on 06 June 2019 in Main articles

By Martin Scott, Andy Webb, Catherine Irwin and Richard Caldow

Abstract The Outer Thames Estuary Special Protection Area (SPA) was classified in 2010 in recognition of its importance for wintering Red-throated Diver Gavia stellata, a species listed in Annex I of the EU Birds Directive. At classification in 2010 the SPA was estimated to hold 6,466 individuals on the basis of visual aerial surveys between 1989 and 2006/07. Aerial surveys using digital photography in January and February 2013 produced a revised peak population estimate of 14,161 individuals. A new survey, carried out in early 2018 and reported here, used high-resolution digital video imagery and generated a peak population estimate of 22,280 birds (95% CI 15,611–29,784). This confirms that the Outer Thames Estuary SPA supports by far the largest aggregation of non-breeding Red-throated Divers in UK waters.

To read the issue in full, you can subscribe to BB here

Two Diamond Aviation (‘DA’) 42 Twin Star aircraft completed the 2018 surveys, equipped with bespoke HiDef digital video recording equipment. HiDef Aerial Surveying Ltd