First Breeding Age in Captive and Wild Bearded Vultures<i>Gypaetus barbatus</i>

Antor, Ramón J.; Margalida, Antoni; Frey, Hartmut; Heredia, Rafael; Lorente, Luis; Sesé, José Antonio

doi:10.3161/068.042.0106

Cited by 36 publications

(38 citation statements)

References 26 publications

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“…This tendency has already been suggested for the growing population of the bearded vulture in the Pyrenees (Antor et al . ). Furthermore, in the longest occupied territories, much turnover of breeders would have been expected in the 25‐year study period, because very few individuals would have been expected to reach the maximum possible breeding age.…”

Section: Discussionmentioning

confidence: 97%

Using manipulation of density‐dependent fecundity to recover an endangered species: the bearded vulture Gypaetus barbatus as an example

Ferrer

Newton

Muriel

et al. 2014

Journal of Applied Ecology

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Summary1. Endangered species subjected to reintroduction programmes often occur as small and isolated populations with local high density and depressed fecundity. Variation in territory quality may lead to this low fecundity owing to increasing occupation of suboptimal territories as population density grows, known as the habitat heterogeneity hypothesis (HHH). In this context, food supplementation in poor territories may be used to produce extra young which could be allocated to reintroduction programmes. 2. We analyse the density-dependent fecundity pattern and the underlying mechanism in a small population of bearded vultures Gypaetus barbatus in Arag on (northeast Spain). We then use population simulations to examine the viability of a hypothetical reintroduction programme using extra young produced by supplementary feeding on poor-quality territories and the effect on the donor population. We also compare the economic cost of such a reintroduction programme in relation to the cost of a traditional captive breeding programme. 3. The wild population showed clear negative, density-dependent fecundity regulation driven by the HHH mechanism. Simulations showed that extractions for translocations had no relevant long-term effects on the donor population viability, but a marked population reduction during the extraction period. However, the implementation of supplementary feeding to produce extra young for translocation lessened significantly this expected initial population reduction. 4. Analyses showed that the annual budget of a captive breeding programme for this species could be seven times more expensive than the translocation of extra young produced by food supplementation. 5. Synthesis and applications. Reintroduction programmes based on translocation of wildreared individuals, after a supplementary feeding programme oriented to poor-quality territories, provide a source of young at least seven times cheaper than those from captive breeding programmes. The use of this approach would decrease initial effects on donor population avoiding public criticism. Increasing the number of young released during the first years of the reintroduction decreases total financial cost and increases the final population size in the new area.

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Section: Discussionmentioning

confidence: 97%

Using manipulation of density‐dependent fecundity to recover an endangered species: the bearded vulture Gypaetus barbatus as an example

Ferrer

Newton

Muriel

et al. 2014

Journal of Applied Ecology

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“…Secondly, the local density of available partners may still be too low in the Alps to allow mating choice and pairing to operate properly. For example, two of the released individuals only started to reproduce in their 13th and 17th year of life, respectively, which is an unusually old age for first reproduction in bearded vultures (Brown 1997; Antor et al. 2007).…”

Section: Discussionmentioning

confidence: 99%

When to end releases in reintroduction programmes: demographic rates and population viability analysis of bearded vultures in the Alps

Schaub

Zink

Beissmann

et al. 2009

Journal of Applied Ecology

100

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Summary 1.Reintroductions are commonly used for re-establishing self-sustainable populations in formerly inhabited areas. Reintroductions are expensive, and thus, it is worth performing a thorough demographic analysis of current and likely future population trajectories to guide strategic decisions on release policy. 2. Bearded vultures Gypaetus barbatus were exterminated from the Alps in the late 19th century, mainly due to human persecution. To re-establish them, captive-bred young have been released annually since 1986. Since the first successful breeding in the wild in 1997, the population has increased to 9 pairs in 2006. It is not known, however, for how long releases should be continued to obtain a self-sustaining, viable population. 3. We estimated age-specific survival probabilities with a mark-resighting model and quantified fecundity rates of released individuals. Using the resulting demographic estimates, we built a stochastic population model to estimate population growth rates, and explored the value of continuing to release birds for varying periods into the future. 4. Annual survival probabilities were high (first year of life, 0·88; later years, 0·96); average annual fecundity was 0·6 fledglings per breeding pair. Using the estimated survival probabilities, projected population growth rates would increase with additional years of releases. Yet, the population would grow, even if releases had stopped after 2006. Only if mortality increased by ≥ 50% would the population start to decline. 5. Synthesis and applications. Our population dynamics model provides essential information to optimize decision-making within a major reintroduction programme. From a demographic viewpoint, releases of captive-raised bearded vultures can be ceased in the Alps. The resources freed could be redirected towards a close demographic surveillance of the free-ranging population, with periodic evaluation of its viability and the option to release birds if deemed necessary. Birds available from the captive stock could be used for reintroductions in other areas where the bearded vulture is extinct.

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“…In general, the species reaches adult plumage at 5–6 years old (females before males, [31]), and is first-time-paired and become territorial at an average age of 6.5y old. However, mean age of first breeding is 8.1y, and mean age of first successful breeding is 11.4y [32]. Clutch size is usually two eggs, but only one chick survives due to sibling aggression [33].…”

Section: Methodsmentioning

confidence: 99%

Testing the Goodness of Supplementary Feeding to Enhance Population Viability in an Endangered Vulture

Margalida²,

et al. 2008

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BackgroundHuman-predator conflicts are directly or indirectly threatening many species with extinction. Thus, biologists are urged to find simple solutions to complex situations while avoiding unforeseen conservation outcomes. The provision of supplementary food at artificial feeding sites (AFS) is frequently used in the conservation of scavenger bird populations currently suffering from indirect poisoning, although no scientific studies on its effectiveness have been conducted.Methodology/Principal FindingsWe used a long-term data set of 95 individually marked birds from the largest European core of the endangered bearded vulture (Gypaetus barbatus) to test the long-term effects of specific AFS for bearded vultures on their survival rates (by CMR models) and population dynamics (by Monte Carlo simulations) in an area where fatalities derived from illegal poisoning and the use of other toxics like veterinary drugs have increased over the last several years. Our data support the positive relationship between the use of AFS and survival. However, contrary to theoretical predictions (e.g. high and more stable adult survival among long-lived species), the use of AFS increased only survival of pre-adults. Moreover, AFS buffered the effects of illegal poisoning on this age-class, while adult survival decreased over years. Our simulations predicted a maximum value of extinction probability over a time horizon of 50 years. Population projections run with survival rates expected in scenarios without poisoning predicted the situation of least conservation concern, while including only AFS can maintain a large floater surplus that may delay population decline but fails to reduce poisoning risk among adults.Conclusions/SignificanceAlthough AFS are not effective to save bearded vultures from an expected population decline, they delay population extinction and can be a useful tool for prolonging population viability while combating illegal and indirect poisoning. The eradication of different sources of poisoning is of top priority to ensure the long-term viability of this and many other species.

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First Breeding Age in Captive and Wild Bearded VulturesGypaetus barbatus

Cited by 36 publications

References 26 publications

Using manipulation of density‐dependent fecundity to recover an endangered species: the bearded vulture Gypaetus barbatus as an example

Using manipulation of density‐dependent fecundity to recover an endangered species: the bearded vulture Gypaetus barbatus as an example

When to end releases in reintroduction programmes: demographic rates and population viability analysis of bearded vultures in the Alps

Testing the Goodness of Supplementary Feeding to Enhance Population Viability in an Endangered Vulture

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