Parental investment asymmetries of a globally endangered scavenger: unravelling the role of gender, weather conditions and stage of the nesting cycle

Abstract

ABSTRACTCapsule: In Egyptian Vultures Neophron percnopterus, both sexes invested similar parental effort throughout the breeding period. However, there was variation in the degree of intensity of parental care during some stages of the breeding period, suggesting that sex-role specialization exists for some activities.Aims: To quantify parental care behaviour of Egyptian Vultures for the first time and to examine the role of sex, weather conditions, and stage of nesting cycle on breeding ecology.Methods: We monitored 15 nests of Egyptian Vultures to analyse parental care investment. We collected data on nine different behavioural parameters/activities per sex, which were recorded throughout the entire breeding period. Variation in parental investment was analysed using generalized linear mixed models.Results: Females invested more effort in incubation/brooding (61.45% for females and 31.54% for males) and egg turning (0.45 events/h for females and 0.37 events/h for males) while males contributed more to nest material delivery to the nest (0.67 deliveries/h for males and 0.14 deliveries/h for females). Conversely, both sexes invested the same effort in nestling attendance (21.89% for females and 21.21% for males) and food provisioning (0.28 items/h for females and 0.25 items/h for males). Furthermore, parental investment was not affected by weather, especially during critical moments such as incubation/brooding, however, changeover rate was positively related to temperature.Conclusion: Our results suggest that, in the Egyptian Vulture, one sex is not entirely responsible for a particular task and the compensatory effort of the other mate is required. Finally, our findings indicate that major events such as incubation onset and hatching caused important shifts in the patterns of parental investment.