Density‐dependent productivity in a colonial vulture at two spatial scales

Fernández‐Bellon, Darío; Cortés‐Avizanda, Ainara; Arenas, Rafael; Donázar, José A.

doi:10.1890/15-0357.1

Cited by 21 publications

(1 citation statement)

References 56 publications

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“…Cinereous vultures nest on mature trees in woods on slopes far away from human presence [8,26,27] and from roads [24,[28][29][30][31][32][33], since an important variable in the breeding success of this bird is the absence of any human disturbance [34]. Prior studies on the influence on nest site selection have assessed the effect of the roads in terms of the Euclidean distance to nest site locations [24,[28][29][30][31]35,36]. Other authors report human influence as a function of the distance to an urban area [14] or of the density of the population in the Californian condor (Gymnogyps californianus) [37] or in the Griffon vulture (Gyps fulvus) [38].…”

Section: Introductionmentioning

confidence: 99%

Influence of Anthropogenic Noise for Predicting Cinereous Vulture Nest Distribution

2020

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Natural landscapes are increasingly under anthropogenic pressures, and concern about human impacts on wildlife populations is becoming particularly relevant in the case of natural areas affected by roads. The expansion of road networks is considered among the main factors threatening biodiversity due to their potential for disturbing natural ecosystems on large scales. Indeed, traffic noise pollution reduces the quantity and the quality of natural habitats, and umbrella species are frequently used as indicators of natural ecosystem health. In this sense, there is a variety of GIS-based ecological modeling tools that allow evaluation of the factors that influence species distributions in order to accurately predict habitat selection. In this study, we have combined the use of noise modeling tools and maximum entropy modeling (MaxEnt) to evaluate the relative importance of environmental variables for Cinereous vulture (Aegypius monachus) nesting habitat selection within a mountainous forest in Spain. As a result, we found that spatial negative influence of roads on wildlife due to road traffic disturbance may have been traditionally overestimated when it has been inferred from distance measurements of wildlife behavior in road surroundings instead of from considering road traffic noise level exposure. In addition, we found a potential risk threshold for cinereous vulture breeding around roads, which ties in with a Leq24h level of 40 dB(A). This may be a useful indicator for assessing the potential impact of human activities on an umbrella species such as, for instance, the cinereous vulture, whose breeding does not take place where road traffic Leq24h levels are higher than 40 dB(A).

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Section: Introductionmentioning

confidence: 99%

Influence of Anthropogenic Noise for Predicting Cinereous Vulture Nest Distribution

2020

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Too much is bad: increasing numbers of livestock and conspecifics reduce body mass in an avian scavenger

Donázar

Barbosa

García‐Alfonso

et al. 2020

Ecological Applications

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Individual traits such as body mass can serve as early warning signals of changes in the fitness prospects of animal populations facing environmental impacts. Here, taking advantage of a 19‐yr monitoring, we assessed how individual, population, and environmental factors modulate long‐term changes in the body mass of Canarian Egyptian vultures. Individual vulture body mass increased when primary productivity was highly variable, but decreased in years with a high abundance of livestock. We hypothesized that carcasses of wild animals, a natural food resource that can be essential for avian scavengers, could be more abundant in periods of weather instability but depleted when high livestock numbers lead to overgrazing. In addition, increasing vulture population numbers also negatively affect body mass suggesting density‐dependent competition for food. Interestingly, the relative strength of individual, population and resource availability factors on body mass changed with age and territorial status, a pattern presumably shaped by differences in competitive abilities and/or age‐dependent environmental knowledge and foraging skills. Our study supports that individual plastic traits may be extremely reliable tools to better understand the response of secondary consumers to current and future natural and human‐induced environmental changes.

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Long‐term demographic dynamics of a keystone scavenger disrupted by human‐induced shifts in food availability

Almaraz

Martínez

Morales‐Reyes

et al. 2022

Ecological Applications

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Scavenging is a key ecological process controlling energy flow in ecosystems and providing valuable ecosystem services worldwide. As long-lived species, the demographic dynamics of vultures can be disrupted by spatiotemporal fluctuations in food availability, with dramatic impacts on their population viability and the ecosystem services provided. In Europe, the outbreak of bovine spongiform encephalopathy (BSE) in 2001 prompted a restrictive sanitary regulation banning the presence of livestock carcasses in the wild on a continental scale. In long-lived vertebrate species, the buffering hypothesis predicts that the demographic traits with the largest contribution to population growth rate should be less temporally variable. The BSE outbreak provides a unique opportunity to test for the impact of demographic buffering in a keystone scavenger suffering abrupt but transient food shortages. We studied the 42-year dynamics (1979-2020) of one of the world's largest breeding colonies of Eurasian griffon vultures (Gyps fulvus). We fitted an inverse Bayesian state-space model with density-dependent demographic rates to the time series of stage-structured abundances to investigate shifts in vital rates and population dynamics before, during, and after the implementation of a restrictive sanitary regulation. Prior to the BSE outbreak the dynamics was mainly driven by adult survival: 83% of temporal variance in abundance was explained by variability in this rate. Moreover, during this period the regulation of population size operated through density-dependent fecundity and subadult survival. However, after the onset of the European ban, a 1-month delay in average laying date, a drop in fecundity, and a reduction in the number of fledglings induced a transient increase in the impact of fledgling and subadult recruitment on dynamics.Although adult survival rate remained constantly high, as predicted by the buffering hypothesis, its relative impact on the temporal variance in abundance dropped to 71% during the sanitary regulation and to 54% after the ban was lifted. A significant increase in the relative impact of environmental stochasticity on dynamics was modeled after the BSE outbreak. These results provide empirical evidence on how abrupt environmental deterioration may induce dramatic demographic and dynamic changes in the populations of keystone scavengers, with far-reaching impacts on ecosystem functioning worldwide.

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Density‐dependent productivity in a colonial vulture at two spatial scales

Cited by 21 publications

References 56 publications

Influence of Anthropogenic Noise for Predicting Cinereous Vulture Nest Distribution

Influence of Anthropogenic Noise for Predicting Cinereous Vulture Nest Distribution

Too much is bad: increasing numbers of livestock and conspecifics reduce body mass in an avian scavenger

Long‐term demographic dynamics of a keystone scavenger disrupted by human‐induced shifts in food availability

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