Nestling sex ratio is unaffected by individual and population traits in the griffon vulture

Successful captive breeding of vultures due to the double clutching method

After a massive decline, the Griffon Vulture (Gypsfulvus) population in Bulgaria has now stabilised as a result of the hard work of conservation programmes, although it is still listed as an Endangered species (EN) in the country's Red Data Book. Due to a series of unfortunate events, another species - the Cinereous Vulture (Aegypiusmonachus) became extinct in Bulgaria and recovered only recently due to systematic re-introduction efforts. Along with the poor living conditions, a predisposing factor for the decreasing population of the vultures is the fact they hatch only a single egg; two may be laid on exceptions. The survival rate of the young is from medium to low. In that order, a method of double clutching has been applied in the hope of preserving and retrieving both of the vultures. This article aims to introduce the double clutching method in detail, as well as to show the results of its implementation into the breeding programme of the Cinereous Vulture and the Griffon Vulture at the Wildlife Rehabilitation and Breeding Centre of Green Balkans - Stara Zagora NGO. This research studies the time period 2019-2023. The purpose of this study is to compare the results of natural copulation and hatching and those of the double clutching method. The data taken are used for studies for both the Cinereous and the Griffon Vulture's reproduction in correlation with their feeding programme and living conditions. The results of the study will be summarised into the following text for the purposes of shedding light on the positives of the double clutching method.

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

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 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 interspecific 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 uptaking carotenoids present in low concentrations in food when these compounds are not deposited in their integument, which suggests allocation to other functions.