Contrasting parental color-morphs increase regularity of prey deliveries in an African raptor: Data

The paper based on this dataset has been published in Behavioral Ecology with the title "Contrasting parental color-morphs increase regularity of prey deliveries in an African raptor"

Abstract:
Disassortative mating in color-polymorphic raptors is a proposed mechanism for the maintenance of color polymorphism in populations. Selection for such a mating system may occur if there are fitness advantages of mating with a contrasting morph. In the black sparrowhawk (Accipiter melanoleucus), mixed-morph pairs may have a selective advantage, since they produce offspring which have higher survival rates. Two hypotheses, which may explain the mechanism, are the 'avoidance-image' and 'complementarity' hypotheses: The first suggests that within a predator's territory, prey develop a search-image for the more commonly encountered parental morph, for example, the male morph during incubation and brooding. Females of a contrasting morph to their partner would then have higher capture rates once they commence hunting in the later nestling phase. Thus, the avoidance-image hypothesis predicts higher provisioning rates for mixed-morph pairs. Alternatively, the 'complementarity' hypothesis posits that different color morphs exploit different environmental conditions, allowing mixed-morph pairs to hunt under a wider range of conditions and predicts that food is delivered more consistently. We test these hypotheses using nest cameras to record prey delivery rates during the late nestling phase when both parents are foraging. We found support for the 'complementarity' hypothesis, with mixed-morph pairs delivering food more consistently, but not at a higher rate. The higher consistency in prey deliveries may explain the improved survival of the offspring of mixed-morph pairs, and therefore play a role in maintaining the stability of color-polymorphism in this system.