Supplementary feeding and endangered avian scavengers: benefits, caveats, and controversies

Abstract

Large avian scavengers are among the most vulnerable vertebrates, and many of their populations have declined severely in recent decades. To help mitigate this marked reduction in abundance, supplementary feeding stations (SFS; colloquially termed “vulture restaurants”) have been created worldwide, often without consideration of the scientific evidence supporting the suitability of the practice. SFS have been effective and important tools for conservation and reintroduction of avian scavengers. However, negative consequences can result from large aggregations of individual birds, disrupting intraguild processes and promoting density‐dependent decreases in productivity. At the community level, SFS favor the congregation of predators (ie facultative scavengers), increasing predation risk on small‐ and medium‐sized vertebrates in the vicinity of the SFS. These feeding stations might also affect processes of natural selection and even render populations maladapted to their natural environments. We also examine future scenarios for avian scavengers in relation to ecosystem services, to changes in agro‐grazing economies and in land uses, and ultimately to rewilding landscapes where SFS play a controversial role.

Sex- and age-dependent patterns of survival and breeding success in a long-lived endangered avian scavenger

“…The conservation of carrion-eaters in the Old World has focused on the importance of tackling direct and indirect deaths from persecution, mainly due to the ingestion of toxics27. Our study also emphasizes that further studies deepening our knowledge of the potential age and/or sex-specific differences in habitat use and risks of toxicity associated with the use of predictable food sources (dumps and supplementary feeding stations) are urgently needed48.…”

Reintroducing endangered raptors: A case study of supplementary feeding and removal of nestlings from wild populations

“…Some authors have suggested that food provisioning would constitute a major modification of the natural distribution of resources at the ecosystem level, leading to “an uncertain future for populations, functional guilds, and, ultimately, communities” (Cortés‐Avizanda et al., ). We consider this to be erroneous; if one considers “natural” as not human‐influenced, there is already in Europe nothing like a natural distribution of resources.…”

“…California condor, Wilbur, Carrier, & Borneman, ; sparrowhawk, Newton & Marquiss, ; various vulture species, Terrasse, ; common kestrel, Wiehn & Korpimaki, ; Spanish imperial eagle, Ferrer & Penteriani, ; González, Margalida, Sánchez, & Oria, ; bearded vulture, Margalida, ). Despite the widespread use of this technique over the last 50 years, particularly in endangered species, its application in conservation has only recently been critically discussed (Cortés‐Avizanda et al., ), revealing important differences in evaluation of the technique. Some claim major beneficial effects at the population level, but others little or no effect (Carrete, Donázar, & Margalida, ; González et al., ; Margalida, ; Margalida et al., ; Oro, Margalida, Carrete, Heredia, & Donazar, ).…”

Importance of Long-Term Studies to Conservation Practice: The Case of the Bearded Vulture in the Pyrenees

“…The provision of supplementary food at artificial or supplementary feeding stations or ''vulture restaurants'' (hereafter SFS), a well-established management tool in the conservation of scavenger populations Moreno-Opo et al 2015;Cortés-Avizanda et al 2016), appears to be a potentially useful solution worldwide. SFS has frequently been used to facilitate the recolonization of abandoned areas (Mundy et al 1992), or to provide safe food sources in areas where carcasses are baited with poisons to control carnivores (e.g.…”

“…In this sense, additional conservation actions, such as supplementary feeding, can buffer the negative effects of policy change on demographic parameters ). However, because supplementary feeding can also have detrimental effects (Carrete et al 2006b;Robb et al 2008;Cortés-Avizanda et al 2016), this tool should only be used as a precautionary measure until the recovery of the previous scenario (i.e. availability of domestic carcases in the field) is achieved.…”