Vultures feeding on the dark side: current sanitary regulations may not be enough

Abstract

Summary It is widely acknowledged that the conservation of vultures, a group of birds threatened worldwide, requires the management of safe, high-quality human subsidies, free of potentially harmful toxic compounds. Additionally, in Europe, the supply of livestock carcasses is subject to current sanitary regulations. It is largely unknown how vultures use sources of food of different abundance, predictability, or different legal status and how individual features shape these preferences. To answer these questions, we took advantage of information yielded by 35 GPS-tagged adult Eurasian Griffon Vultures Gyps fulvus living in a region of northern Spain, which hosts one of the most important European populations. Our results indicated that vultures preferably used predictable feeding sites, such as carcass dumping sites, intensive farms and landfills which together account for the 62% of the observed feeding sites. Less than 10% of all observed sites had permission of authorities for the disposal of the carcasses. Interestingly, sites with large accumulations of carcasses were less used that those with intermediate amounts of food probably because of high intraspecific competition. In addition, sex and breeding status also played a role with males and breeding birds being more prone to visit the studied intensively managed feeding places. This vulture population is heavily dependent on food sources which are not under legal control where the birds could be at risk of intoxication and pathogen acquisition. Hence, current legal scenario allowing farmers to abandon carcasses in their exploitations seems insufficient. The future of vultures in highly anthropized regions is uncertain if interdictory regulations on the abandonment of carcasses of intensive livestock are applied. Additionally, conservation scenarios based on food subsidization must consider the effects of environmental and individual variability. We need science-based strategies ensuring the long-term viability of avian scavenger populations within a scenario of anthropized landscapes and livestock farming intensification.

Second-generation anticoagulant rodenticides in the blood of obligate and facultative European avian scavengers

“…Moreover, we found that both kites and Egyptian vultures showed a high prevalence of individuals containing multiple different SGARs (four compounds were identified in a single Egyptian vulture). These exposures could relate to the foraging and dietary habits of these species, which comprise the carrion of small and medium-sized mammals, such as rodents, as well as carnivores (Oliva-Vidal et al, 2022) and large quantities of garbage and food items gleaned from landfill sites and livestock farms (Margalida et al, 2012;Tauler-Ametller et al, 2017Arévalo et al, 2022;Fernández-Gómez et al, 2022). In the specific case of the red kite, a diet based on small rodents is more likely to result in bioaccumulation of ARs (Coeurdassier et al, 2014) although this species is well-known for frequently exploiting garbage dumps, slaughterhouses and agricultural areas (Seoane et al, 2003;García-Macía et al, 2022).…”

“…They could also be eaten by obligate scavengers (i.e., species that depend entirely on carrion, such as vultures) and facultative scavengers (i.e., species that exploit carrion opportunistically, including raptors, corvids and mammalian carnivores) (Hindmarch and Elliott, 2018). In addition, avian scavengers frequently exploit food sources in urban landfill sites (Tauler-Ametller et al, 2017Plaza and Lambertucci, 2018;Arévalo et al, 2022;Fernández-Gómez et al, 2022), where SGARs are constantly deployed (Coeurdassier et al, 2018). Despite these risk factors, few studies have investigated the exposure of avian scavengers to SGARs, particularly vulture species (Sánchez-Barbudo et al, 2012;Mateo et al, 2015;Plaza et al, 2019;Rial-Berriel et al, 2021;Moriceau et al, 2022).…”

Large‐scale movement patterns in a social vulture are influenced by seasonality, sex, and breeding region

“…This gender variation in seasonal fidelity may respond to differences in resource selectivity (Delgado‐González et al, 2022 ; Hertel et al, 2020 ). In fact, according to Fernández‐Gómez et al ( 2022 ) males may be more prone to feed on predictable resources such as supplementary feeding stations or vulture restaurants, while females may rely on more ephemeral and less clumped food resources. Thus, there may be parallel strategies in the large‐scale exploitation of space and, therefore, sexual spatial segregation (see also Perrig et al, 2021 ).…”

A lifetime track of a griffon vulture: The moving story of Rehovot (Y64)

“…While such long‐term tracks of free‐ranging animals are still rare, they have the potential to show, on a broad scale, how space use changes seasonally and throughout an animal's lifetime (e.g., foraging or roosting behavior; Harel, Duriez, et al, 2016; Spiegel et al, 2015). In endangered species, the age structure of the population may change as the population decreases (Jackson et al, 2020), which, if combined with age‐specific space use (Weimerskirch, 2018), may regulate the ecosystem services the species provides (e.g., nutrient transport; McInturf et al, 2019 or, in the case of vultures, sanitation services; Fernández‐Gómez et al, 2022).…”