It is published in the respected journal British Birds and looks at red-throated divers, a protected species found in large numbers in winter only at small number of sites around the UK coast.

Although the birds have been recorded in numbers large enough to warrant international protection at some sites, researchers suspected that previous estimates had been too low.

Traditionally these estimates have been gathered by observers with binoculars who manually count birds from the shore, in boats or from aircraft; methods that require a ‘close approach’ and risk scaring away the very birds that are being counted.

1411_RIPA_German survey

Newer techniques pioneered by APEM instead use ultra-high resolution digital cameras fitted to survey aircraft to capture thousands of images over an area. The aircraft fly in carefully configured flight plans high over the sea to ensure high quality data and no disturbance of the birds.

The images are then analysed on computers by ornithologists to determine the species, numbers and flight heights of the birds. Well over 90 per cent of the birds captured in the images can be identified to their species.

A series of extensive aerial surveys off the east coast of England carried out by APEM on behalf of Natural England, provided the opportunity for APEM’s ornithologists to contribute to the new research.

APEM’s head of ornithology, Dr Mark Rehfisch, said: “Data on the numbers and distribution of seabirds is not just of academic interest. It’s used to help determine important decisions in the real world, such as which areas should be protected and whether offshore windfarms can be built.

“Our innovation of using ultra-high resolution digital aerial surveys to capture images of the birds has given us much more accurate data, confirming that previous estimates of the numbers of red-throated divers in the Outer Thames Estuary Special Protection Area were too low.”

The peak estimate of 14,161 red-throated divers recorded using ultra-high resolution aerial surveys in February 2013 was more than twice the estimate of 6,466 that had been recorded for the same area using visual surveys in 2008.

If you have any queries, please contact Steph McGovern, head of ornithology.
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