Report from Fågelsundet

"860 mm" said Kozue, measuring the half-wind span of the first greater black-backed gull (havstrut, Larus marinus) that we will GPS tag. After a few more measurements (head + bill, wind length etc) we decide it's a male.

It's early May on Sweden's east coast, just to the south of Gävle, where we will be GPS tracking a range of the larger gull species (herring, lesser black-backed, and greater black-backed) and the magnificent Caspian tern.

We are using solar-powered GPS trackers (see: http://www.uva-bits.nl/) which have a wi-fi like wireless connection to a base-station antenna. This system allows us follow both the foraging flights and migratory movements of the species in great detail.

Questions we will look at include, how do the different species differ in their flight abilities? Do they respond different to wind conditions? How large are their 'home-ranges'?

We caught our male greater black-backed gull using a 'spring-trap', set at its nest. When he returned to incubate the eggs at the nest he was caught.

We then deployed a GPS tracker and took various measurements. In part these will be used to compare flight between gulls with different wing areas and aspect ratios (ratio of wing-span to wing-cord).

As we release him, we wonder, what story will we learn from his GPS tag?


//Tom