Vulture culture: dietary specialization of an obligate scavenger

Abstract

Individual dietary variation has important ecological and evolutionary consequences. However, it has been overlooked in many taxa that are thought to have homogeneous diets. This is the case of vultures, considered merely as ‘carrion eaters’. Given their high degree of sociality, vultures are an excellent model to investigate how inter-individual transmissible behaviours drive individual dietary variation. Here, we combine GPS-tracking and accelerometers with an exhaustive fieldwork campaign to identify the individual diet of 55 griffon vultures ( Gyps fulvus ) from two Spanish populations that partially overlap in their foraging areas. We found that individuals from the more humanized population consumed more anthropic resources (e.g. stabled livestock or rubbish), resulting in more homogeneous diets. By contrast, individuals from the wilder population consumed more wild ungulates, increasing their dietary variability. Between sexes, we found that males consumed anthropic resources more than females did. Interestingly, in the shared foraging area, vultures retained the dietary preference of their original population, highlighting a strong cultural component. Overall, these results expand the role of cultural traits in shaping key behaviours and call for the need of including cultural traits in Optimal Foraging models, especially in those species that strongly rely on social information while foraging.

Age-Specific Demographic Response of a Long-Lived Scavenger Species to Reduction of Organic Matter in a Landfill

“…In addition, in some ecological systems and species, feeding on landfills could have a detrimental effect on chick and juvenile survival since individuals of these ages are more susceptible than adults to the abovementioned risks (e.g., [36,37]. Nevertheless, for long-lived scavengers such as vultures, the overall trade-off seems to be positive, as current evidence supports the idea that landfills represent an important food source that may partially support some populations [27,30,[38][39][40].…”

“…This synchronized reduction in food resources could have significant consequences for demographic rates and ultimately threaten an important food source for numerous species that rely on these facilities and, in particular, for the griffon vulture population in the northeast Iberian Peninsula. These vultures are highly specialized and feed on carcasses originating from extensive livestock farming and landfills [26,38] and younger age classes being particularly dependent on landfills, especially during periods of wild food scarcity such as winter [27,28,30,31,100]. As a result, the reduction in food and the potential closure of landfills may lead to a dramatic shift in trophic strategy among scavenger species, forcing them to rely more on less predictable food sources (and, to some extent, predictable ones like supplementary feeding sites for scavengers), as previously predicted for Egyptian vultures (Neophron percnopterus) [40].…”

“…Vultures are long-lived vertebrates and are among the most threatened scavenger species, with more than 80% of species listed as Threatened or Near Threatened on the IUCN Red List [41][42][43]. In a transitioning scenario towards a worldwide circular economy model that aims to reduce waste and close landfills, it is imperative to evaluate the effects that these regulations may have on the demographic parameters of the vulture populations that have adapted to feed in these infrastructures [26,38]. Previous studies have demonstrated that a drastic reduction in food availability can increase vulture mobility and decrease the apparent survival of adults [44,45].…”

A long‐lasting, distant journey of a male griffon vulture informs on the success of differential parental investment

“…First, we show that a particular individual griffon vulture from a colony located in central Spain recurrently uses the same distant region in the southwest of the Iberian Peninsula for temporary settlement when leaving its breeding area during or after the reproductive season. This temporary settlement in these distant areas can imply a change in foraging habits and diet (Arrondo et al, 2023), may be influencing its nutritional condition and the risk of acquiring and dispersing pathogens, and ingesting different pharmaceutical drugs derived from the consumption of stabled versus extensive livestock (Blanco et al, 2019; Pitarch et al, 2017; Plaza et al, 2020), which has important conservation implications (Cortés‐Avizanda et al, 2016). Therefore, knowledge of feeding opportunities and their associated risks in breeding and temporary distant settlement areas should be considered together to establish efficient management measures for these highly mobile species (Arrondo et al, 2023; Peters et al, 2023).…”

“…This temporary settlement in these distant areas can imply a change in foraging habits and diet (Arrondo et al, 2023), may be influencing its nutritional condition and the risk of acquiring and dispersing pathogens, and ingesting different pharmaceutical drugs derived from the consumption of stabled versus extensive livestock (Blanco et al, 2019; Pitarch et al, 2017; Plaza et al, 2020), which has important conservation implications (Cortés‐Avizanda et al, 2016). Therefore, knowledge of feeding opportunities and their associated risks in breeding and temporary distant settlement areas should be considered together to establish efficient management measures for these highly mobile species (Arrondo et al, 2023; Peters et al, 2023). Second, our observations show how the apparent neglect in the breeding behavior of a novice male griffon vulture can be compensated by its female mate, which successfully completed the breeding event.…”