Influence of food limitation on reproductive performance of burrowing owls
Reproductive strategies of birds are shaped by patterns of food supply, yet empirical evidence of the consequences and mechanisms of food limitation on reproductive performance is inconsistent, probably due to variable responses from species of differing life-history strategies.
We tested the hypothesis that food supplementation would increase reproductive rates of a nonmigratory population of Burrowing Owls (Athene cunicularia) via direct and indirect pathways. We predicted increasing food availability would directly increase growth and survival of the youngest nestlings and would indirectly decrease predation rates of eggs and nestlings by increasing nest attendance. We experimentally supplemented food from clutch completion through brood-rearing during two breeding seasons (April–July 1999 and 2000) in the agricultural matrix of the Imperial Valley, in southeastern California. In both years, hatching success (hatchlings/egg laid) was similar between supplemented and non-supplemented nests, but the proportion that survived to 28 d was higher in food-supplemented nests. Growth rates and survival rates of last-hatched young were lower in non-supplemented than supplemented nests in only one year of the study. A greater proportion of hatchling deaths were attributed to starvation in non-supplemented nests. Nest attendance was greater in supplemented nests although low predation for supplemented and non-supplemented nests resulted in no effects on reproductive success. Our results were consistent with the brood-reduction hypothesis that predicts that food supplementation would result in a greater number of fledglings by increasing survival of the youngest nestlings through increased growth rates when hatching asynchrony exists and food is limited.
Titel: Influence of food limitation on reproductive performance of burrowing owls.
Auteurs: Haley KL en Rosenberg DK.
Source: Journal of Raptor Research (2013) volume 47, issue 4