Supplementary feeding during the chick-rearing period is ineffective in increasing the breeding success in the bearded vulture (Gypaetus barbatus)

Abstract

One of the most widespread tools in the conservation of scavenger species is the provision of supplementary food. However, scientific studies on its effectiveness have been rarely conducted. Here, we present the first results of an experimental specific supplementary feeding programme applied from hatching to 45-60 days, aimed at increasing the breeding success of an obligate brood reducer, the threatened bearded vulture Gypaetus barbatus. We tested its effectiveness in the Spanish Pyrenees, the locale of the most important population of this species in the European Union, in which a regressive trend in breeding parameters has been observed in recent years. We compared the breeding success in nests with supplementary food to non-supplemented control nests. Supplementary food did not significantly increase global breeding success (supplemented nests, 0.793±0.193 chicks per pair with eggs hatched vs non-supplemented nests, 0.771±0.185) or the individual breeding performance of the territories (supplemented period, 0.712±0.307 vs nonsupplemented period, 0.642±0.311). The similar values obtained suggest that the specific supplementary feeding programme applied during the chick-rearing period is apparently ineffective at increasing breeding success. The results suggest that, at least in the study area, factors that provoke breeding failure after hatching continue to operate independently of the supplementary feeding programme. Although more research on this subject is required, these preliminary conclusions should be taken into account by managers in order to optimise the investment of economic resources and to better prioritise the future establishment of alternative conservation actions.

Intra-specific competition in foraging Griffon Vultures Gyps fulvus: 2. The influence of supplementary feeding management

“…However, their maintenance in the long term is questioned by many wildlife managers and researchers (Piper 2006, Robb et al 2008. In territorial raptors such as Bearded Vultures, HFS were found to have no effect on improvement of breeding success or even negative effects on adult survival (Oro et al 2008, Margalida 2010. Another concern is a change in behaviour, with vultures becoming accustomed to HFS and not willing to search food by themselves (Boutin 1990, Houston 2006, Robb et al 2008.…”

“…In Bearded Vultures, feeding stations are concentrating young individuals around feeding sites and can prevent the colonization of new sites, where food may be harder to find, and at the same time can disturb local territorial breeding pairs (Oro et al 2008). More generally, supplementary feeding did not improve the breeding success of Bearded Vultures in Spain (Margalida 2010). In that species, breeding strategies may even be modified in the vicinity of feeding stations and the resulting trios have a lower productivity than conventional monogamous breeding pairs , Carrete, Donazar, Margalida & Bertran 2006.…”

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

“…This is the case of the bearded vulture (Gypaetus barbatus), a long-lived, flashing endangered species that provides critical ecosystem services such as disease and pest control (Margalida et al 2011a;Margalida and Colomer 2012;Donázar et al 2016), indirect greenhouse emissions regulation (Morales-Reyes et al 2015 or cultural inspiration and recreational activities . In Europe, a total of 215 territories have been documented in mountainous ecosystems (del Hoyo et al 1994;Margalida 2010a), 130 of which are present on the southern face of the Pyrenees (Spain). In this region, several management and conservation actions have been carried out during the last 30 years to improve the status of the species.…”

“…Significant human and economic efforts have been dedicated to recovering this threatened species in Europe to reverse its negative population demographic trend (i.e. conservation programmes and reintroduction projects), through funds provided by several life projects, administrations and NGOs (Schaub et al 2009;Margalida 2010a).…”

“…In this region, several management and conservation actions have been carried out during the last 30 years to improve the status of the species. The historical decline in Europe has been associated with anthropogenic actions, mainly poisoning and direct persecution Margalida 2010a). Significant human and economic efforts have been dedicated to recovering this threatened species in Europe to reverse its negative population demographic trend (i.e.…”