|Photo: G. Tavecchia|
viernes, 13 de febrero de 2015
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
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.