Tracking movements of Gulls
Gulls are not known as migratory birds. Yet, they abandon their breeding grounds almost completely each year and shift their distribution in a SW direction to winter in the south of The Netherlands, in Belgium and in northern France. An important breeding colony for ongoing research is found on the Wadden Islands, Texel. The breeding ecology has been studied since 2006, and in 2013 we started tracking Herring Gulls with UvA-BiTS GPS loggers.
There is no dispute about the international importance of the Wadden Sea for myriads of migratory waterbirds. Most of these birds breed further to the north and winter further to the south: for them, the Wadden Sea is their stop-over. Some birds, however, rely on the Wadden Sea for breeding. The Herring Gull and the Lesser Black-backed Gull, for example. The Lesser Black-backed Gull is a newcomer; with a first breeding attempt on Terschelling in 1926. Following a long period with very small numbers, the population exploded in the 1970s and 1980s. Herring Gulls are with us for as long as we care to remember. Today, colonies of large gulls, each numbering thousands of breeding pairs, can be found on all Wadden Sea islands.
Current tracking work, together with the collection of prey items in the colony, will help us identify their primary foraging areas and resources during the breeding season, as well as their movement patterns throughout the non-breeding season.Read more +
10 April 2020The 169 individual groynes, on average some 230m apart and each sticking ~30-40m into the North Sea, form safe havens for roosting birds.
7 March 2020Modern GPS tracking techniques allowed us to follow our Herring Gulls in unprecedented detail. We could now see how they commute between the colony...
10 Januari 2020Herring Gulls get more and bigger young when searching for food in garbage dumps and in cities (in Dutch). English abstract A gull's portrait: here by Susanne van Donk.