Parental care of the endangered chaco eagle (Buteogallus coronatus) in Central Argentina

Abstract

Sexual differences in parental care investment may affect individual survival or performance, and also demography. We investigated parental-care behavior of the endangered Chaco Eagle (Buteogallus coronatus) to evaluate implications for population conservation in semiarid habitats of central Argentina. From 2004 to 2012, we monitored three breeding attempts using video recording (275 hr) during the incubation period, and nine pairs during the nestling-rearing period by means of video recording (1087 hr) and focal observations at nests (232 hr). Chaco Eagles showed a strong division of parental care by sex. Females contributed significantly more than males to incubation, shading/brooding, and feeding of the nestling, whereas males provided prey to females during incubation and to nestlings during the early nestling-rearing period. Foraging males, which spend more time away from the nest, may be more exposed to anthropogenic activities and negative interactions with humans. If males are more vulnerable to such effects, this could decrease the survival of breeding males and potentially increase the recruitment of immature males to the breeding population. In this event, the ability of the inexperienced immature males that replace the adult eagles to cope with the food and care demands of the mate and offspring is critical for ensuring Chaco Eagle population maintenance.