Restringido

Abstract In raptors, brood size seems to be closelyrelated to the size of prey brought to the nest, the deliveryrate and the degree of parental effort. In the case of Pere-grine Falcons (Falco peregrinus), any increase in the sizeof prey is considered to be linked to the increased role ofthe female in hunting. We investigated the possible effectsof differences between sexes in prey composition on thebrood size of a Peregrine Falcon population in northernSpain during 1998–2010. The study area was located on theGulf of Biscay, in the middle of the Western EuropeanFlyway, hence a wide range of prey species were availableduring the breeding season. We monitored a total of 320Peregrine nests, which produced 603 fledglings (averagebrood size = 2.67) and identified 2,832 prey, from 128different bird species. Our results indicate that brood sizewas negatively related to bad weather (e.g. rainfall inApril), but not with the body mass of the prey speciesdelivered to the nest. There were no significant differencesin body mass between attacked versus captured prey, norwas mass affected by the sex of the attacking Peregrine,and gender had no significant effect on the probability of asuccessful capture. Therefore, males and females huntedprey species of similar body size. Our data suggest thatprey size is not related to the number of fledglings, lthough this may play an important role; Peregrines cancompensate by hunting for more or larger prey.

Zuberogoitia, I., Martínez, J.E., González-Oreja, J. A., Calvo, J. F., Zabala, J. 2012. The relationship between brood size and prey selection in a Peregrine Falcon population located in a strategic region on the Western European Flyway. J. Ornithol 154(1): 73-82.