European policies on livestock carcasses management did not modify the foraging behavior of a threatened vulture

Abstract

Policy decisions have the potential to affect biodiversity conservation and modify, among other factors, animal demography, behavior and ecological processes. This became manifest in Europe in the past decade in light of the appearance of bovine spongiform encephalopathy (BSE). However, the obvious effects of policy decisions on foraging behavior are lacking. Here, we use data from a long-term study (1992–2015) of the ecology of the bearded vulture Gypaetus barbatus in the Pyrenees to assess whether or not the implementation of health policies in the period 2006–2011 really did affect this vulture's foraging behavior and breeding success. To test this, we used the frequency of nest changeovers (between 1992 and 2015) as a surrogate for the time invested in searching for and obtaining food. Additionally, between 2006 and 2015 we monitored the movements of 20 bearded vultures with GPS satellite transmitters. Our findings show no differences between annual home range sizes and/or the time used to search for food either before, during or after the imposition of health regulations. No differences between periods (during or after health regulations) were found in the use of supplementary feeding sites (SFS). An analysis of food available indicates that this similarity of use in different periods could be explained by the high habitat quality in the Pyrenees and the good availability of trophic resources. Our results suggest that diet plasticity and habitat quality compensate for the sudden effects of food shortages and so question the true usefulness of SFS in buffering a quantitative food deficit. We discuss the implications of these results from both ecological and conservation perspectives.