Three year seabird tagging project starts in Alderney

AWT gannet and shag study on Burhou, May 2013. Photo Alderney Wildlife TrustFrom Alderney Wildlife Trust

A team from The University of Liverpool and the Alderney Wildlife Trust made the first of what will be many visits to Alderney’s seabird colonies on 20th May. The team started the process on Burhou capturing shags, a declining seabird of which Alderney has a significant number. Once caught, each bird will be fitted with a small waterproof GPS data-logger aimed to uncover much about the birds’ lifecycle, their feeding and foraging habits and the potential impacts that marine developments, such as renewable energy installations, may have. It may also throw light onto issues such as fishing practice and marine pollution incidents within the English Channel.

Shags. Photo by Mick DrydenAfter some intense sessions trying to catch and tag the somewhat elusive shags, the team will move on to tagging the much more accessible but aggressive northern gannets. This will be done with the help of the Channel Island Ringers and other organisations. By monitoring two species at once, one which tends to feed close to its nesting site (the shag) and the other which can travel well over 200km on a single foraging trip (the gannet), it is Northern gannets. Photo by Mick Drydenpossible to get a much broader picture of how our breeding birds use Channel Island, French and UK waters to survive. Both bird species fly between roosting and feeding sites and capture their prey by diving into the water column. This means that they could encounter wind turbines while flying above the water and tidal turbines while foraging below.

Each GPS tag will stay on the birds for approximately five (shags) or 10 (gannets) days before the team returns to retrieve them. These tags will not cause the birds any discomfort and will fall off by themselves after a few weeks if not retrieved as planned. The information the tags contain can be downloaded and, it is hoped, contribute to a growing body of information which is forming the basis of a PhD being undertaken by Victoria Warwick-Evans.

A trial project undertaken in 2011 saw 23 GPS data loggers attached to northern gannets breeding on Les Étacs, Alderney. Within six days, 17 of the loggers had been retrieved, revealing the locations of 34 foraging trips. Interestingly individuals seemed to specialise their feeding in different areas with some flying to the south coast of England, some southwards to Jersey and others heading east towards Le Havre on the French coast. Amazingly on one occasion a gannet made a 340km round trip, and several made two trips to the South Coast of England within 72 hours. Preliminary analysis suggests that Alderney’s gannets make longer foraging trips than those breeding at some UK colonies but are comparable to the distances travelled by their closest neighbours breeding on Les Sept Îles, Brittany. Evidence also suggests that there is little overlap between the foraging sites of the gannets from Brittany and those from Alderney: the French gannets tend to stick to the western English Channel whereas Alderney’s appear to feed more towards the eastern end of the Channel.

Gannets map 2011. Alderney Wildlife TrustVictoria from the University of Liverpool says that she is “thrilled to be part of a team studying the intricate foraging behaviours of these impressive seabirds, and excited to have the opportunity to use this data in the development of models in order to predict any effects that offshore developments may have on these seabird populations.”

Tim Morley, Ecologist from the Alderney Wildlife Trust says that “the chance to better understand the life of our seabirds during the breeding season is something that excites us at the AWT, and we are privileged to be working with the University of Liverpool team in this venture. The results will be a key focus of our future conservation efforts amidst growing concern over marine pollutants, fishing practises and the intensity of traffic through the British Channel”.

The project is being run by The University of Liverpool, funded by the Natural Environment Research Council (NERC) and the Alderney Commission for Renewable Energy (ACRE), with the support of the Alderney Wildlife Trust.

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