Interspecific differences in plasma carotenoid profiles in nestlings of three sympatric vulture species

Abstract

Carotenoids are diet-based micronutrients important in health and coloration signaling. Related species with similar diets can differ in the kinds and levels of circulating carotenoids, which suggests specific physiological mechanisms to efficiently utilize these micronutrients, regardless of their availability. We explored whether diet and parental provisioning of unusual sources of carotenoids (fresh vegetal matter and vertebrate feces) can explain the occurrence and concentrations of carotenoids in the cinereous vulture Aegypius monachus, griffon vulture Gyps fulvus, and Egyptian vulture Neophron percnopterus nestlings, even when these pigments appear to not be deposited in their integumentary system. A greater diversity of wild prey in diet could be behind the profile of higher concentrations of carotenoids in the Egyptian vulture, the species with carotenoid-dependent coloration during adulthood, while differences in diet composition between cinereous and griffon vultures do not translate to different carotenoid profiles. The carotenoid profile appears to not be related to the ingestion of unusual matter rich in these compounds, although the infrequent occurrence of lycopene and an unidentified γ-carotene-like compounds suggest that these vultures may be exploiting vegetal matter that left no identifiable unconsumed remains in the nest of Egyptian vultures. The consumption of green plant material by griffon vultures does not result in especially high levels of carotenoids when compared to the carotenoids found in cinereous vultures, which do not consume green plant material. Ungulate feces were not provisioned to Egyptian vulture nestlings, despite the fact they contain carotenoids that adults need for appropriate coloration. Overall, this study indicates that diet differences alone appear insufficient to explain contrasting inter-specific carotenoid profiles, especially since all types of food consumed are considered to be poor in carotenoids, except vegetable matter. We suggest that nestling Egyptian vultures are comparatively efficient in up taking carotenoids present in low concentrations in food when these compounds are not deposited in their integument, which suggests allocation to other functions.

A long‐lasting, distant journey of a male griffon vulture informs on the success of differential parental investment

“…4000 km 2 between the provinces of Seville and Badajoz, about 450 km from its nest (Figures 2A–D and 3; Data are available in Oltra, 2023). In this area, the individual exploited carcasses of extensive and semiextensive sheep and cattle farms (Delgado‐González et al, 2022), which contrasts with the diet it had in the breeding area, based on carcasses of stabled livestock (pigs and poultry) available in vulture restaurants and in the surroundings of the farms (Blanco, 2014; Blanco & Hornero‐Méndez, 2023). Meanwhile, the nestling fledged at an age of about 104 days, 19 days after its father left the colony.…”

Rabbits or Refuse? Landfill Use and Relevance as a Food Source for an Increasing Wintering Population of the Red Kite

“…The pellets of this species generally consist of the hair or feathers of the consumed animals. This makes it impossible to quantify the minimum number of specimens consumed due to the difficult-to-control variations derived from the consumption of individual animal fragments obtained by scavenging, which also prevents the quantification of the biomass contributed by each type of food, as occurs in other scavenger species [62].…”