Gull tracking on the news!

Photo: G. Tavecchia

GSM/GPS data are generating a growing interest in gulls' feeding strategy. A new article by E. Soto in the newspaper El Mundo (here) has just been published on the monitoring of Yellow-legged Gulls at Dragonera. Long-distance tracks and daily feeding strategies are on the spot. Thank also to the help of T. Muñoz from the GOB (Grup Balear d'Ornitologia I Defensa de la Naturalesa)

YLG 2015 campaign ended today

 

The Yellow Legged gull campaign ended today with twenty-seven gulls marked, two surveys and eighty clutches measured along the path to the Llebeig lighthouse. Thank to everyone who helped. Eleanor Falcons have just arrived, time for us to go. 

See you next year!

New publication on seabirds !

Steigerwald, E., Igual, J.-M., Payo-Payo, A., and Tavecchia G. Effects of decreased anthropogenic food availability on an opportunistic gull: evidence for a size-mediated response in breeding females Ibis in press

Photo: G. Tavecchia

Some opportunistic vertebrates exploit, and may largely rely upon, food generated by human activities. Better understanding the influence of this additional anthropogenic food on species’ ecology would inform sustainable waste management. In the Balearic Archipelago of Spain, closure of an open-air landfill site provided an experimental setting to measure the effect of removing anthropogenic food on the average body mass, breeding parameters and body condition of opportunistic Yellow-legged Gulls Larus michahellis. After landfill closure there was a significant decline in the average body mass of breeding females and males (-10.4% and -7.8%, respectively), in average egg volume (-4.8%), and a shift in the modal clutch size from 3 to 2 eggs. Body condition decreased after landfill closure in both sexes. In breeding females, the drop in body weight was greater for birds with a low body size index. The differential response to a reduction of anthropogenic food between small and large birds suggests that food of anthropogenic origin contributes to temper the effects of natural selection, making the long-term demographic effects of changes in food supply difficult to predict.