Spatially explicit poisoning risk affects survival rates of an obligate scavenger

Monadjem, Ara; Kane, Adam; Botha, André; Kelly, Chris; Murn, Campbell

doi:10.1038/s41598-018-22632-y

Cited by 29 publications

(29 citation statements)

References 53 publications

(58 reference statements)

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“…Sensitivity analyses showed that an increase in the severity of poisoning episodes would lead to a significant increase in the extinction probabilities of the Bosa population. Several authors have highlighted the importance of mitigating this threat when developing PVAs in vultures (Oro et al 2008, Monadjem et al 2018. However, the eradication of the illegal use of poison is neither easy nor time-efficient, and alternative measures acting synergistically in enhancing survival rates should be implemented to allow more time for tackling this threat (Oro et al 2008).…”

Section: Discussionmentioning

confidence: 99%

Assessing the effects of different management scenarios on the conservation of small island vulture populations

Aresu¹,

Rotta

Fozzi³

et al. 2020

Bird Conservation International

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Summary Although the population of Griffon Vulture Gyps fulvus is significantly increasing in Europe, in Italy the species is still on the Red List as ‘Critically Endangered’, with the last natural population persisting on the island of Sardinia. Several episodes of poisoning hampered the success of conservation actions implemented in the years 1987–1995. In 2005 there were estimated to be only 31–32 territorial pairs, with the population occupying the territories of Alghero and Bosa. We used a long-term dataset of reproductive records from the Sardinian Griffon Vulture populations to run a population viability analysis (PVA) to evaluate the extinction risk using the Vortex simulation software. The model estimated the probability of extinction over the next five generations (estimated generation time: 11 years, simulation time used: 55 years) as 96.4% for the Alghero population, and near-zero for the Bosa population. We used sensitivity analyses to understand how uncertainty about parameter values affect model outcomes. Population projections were evaluated under different management scenarios tackling the main threats (poisoning and human disturbance) and implementing conservation actions (supplementary feeding and restocking). Our results showed that population size is a critical factor in affecting the projections of population dynamics of Griffon Vultures. Sensitivity analyses highlighted the importance of poisoning events to population persistence and showed that juvenile and adult mortality rates had a secondary impact on population viability. The only conservation measure effective in significantly increasing stochastic growth rates in the Alghero population, whose initial population was set at five individuals, was the complete removal of poisoning events. When targeting the Bosa population (initial population size 94 individuals), supplementary feeding, mitigation of the risk of poisoning episodes, restocking, and mitigation of human disturbance in the reproductive sites significantly increased stochastic growth rate. A cost-effectiveness analysis should be performed to prioritise interventions.

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Section: Discussionmentioning

confidence: 99%

Assessing the effects of different management scenarios on the conservation of small island vulture populations

Aresu¹,

Rotta

Fozzi³

et al. 2020

Bird Conservation International

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“…Such a situation was found to affect breeding success in Spanish Imperial Eagle Aquila adalberti, whereby pairs that include non-adults produced less chicks than adult pairs (Margalida et al 2008). Monadjem et al (2018) suggested that poisoning incidents would have greatest impacts on adults, since during feeding, they outcompete juveniles. This could result in a preponderance of young birds in the population.…”

Section: Discussionmentioning

confidence: 99%

Changes in nesting numbers and breeding success of African White-backed Vulture Gyps africanus in north-central Botswana

Leepile

Maude

Hancock

et al. 2020

Bird Conservation International

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Summary African White-backed Vultures were recently uplisted to ‘Critically Endangered’ by IUCN due to declines across their range. Poisoning is widely accepted as the major reason for these declines. Botswana supports a high number of this species (breeding pairs > c.1,200), but as yet no published information exists on their breeding success in the country. However, mass poisonings within Botswana and neighbouring countries have killed thousands of White-backed Vultures in recent years. We therefore expected that nesting numbers may have declined in this region if these poisoning events killed local breeding birds. We used information from aerial surveys conducted between 2006 and 2017 in Khwai and Linyanti, two important breeding areas for this species in north-central Botswana, to determine if there was any change in nesting numbers and breeding success of White-backed Vultures. Results showed an overall 53.5% decline in nesting numbers, with a greater decline in Linyanti than in Khwai. In both areas, breeding success was significantly lower in 2017 than it was 10 ten years earlier. We recommend that similar repeat surveys are continued to provide greater confidence in the trends of both nesting numbers and breeding performance. Population viability analysis suggested that if the productivity levels detected in 2017 were a true indication of current productivity levels for this population, and if recent high poisoning rates continue, this population could be extirpated from the area in the next 13 years.

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“…Our approach is specifically applicable to wildlife populations that are affected by a clear stoppable threat, which would benefit from reintroduction efforts, where sufficient data are available to develop a population model and where the impact of other anthropogenic stressors affecting the wildlife population is negligible or known. Examples are evaluating the reintroduction costs of (a) lions ( Panthera leo ) after restricting trophy hunting (Creel et al, ), (b) African white‐backed vultures ( Gyps africanus ) after reducing poison‐induced mortality (Monadjem, Kane, Botha, Kelly, & Murn, ), or (c) bird species in Guam such as the Mariana Fruit Dove ( Ptilinopus roseicapilla ) after controlling the invasive brown tree snake ( Boiga irregularis ; Rehm, Balsat, Lemoine, & Savidge, ). Given that the prediction of these costs will be inherently uncertain and that uncertainty might inflate further when future projections are to be made based on surrogate data or expert‐based opinions, the precautionary principle may be applied.…”

Section: Discussionmentioning

confidence: 99%

Predicting reintroduction costs for wildlife populations under anthropogenic stress

Hilbers

Huijbregts

Schipper

2019

Journal of Applied Ecology

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1. In conservation decision-making, it is important to have information not only on the likely effectiveness of conservation actions, but also on the corresponding costs. Reintroduction of wildlife is a commonly applied 'last resort' conservation measure. However, a quantitative approach to predict the costs of reintroduction for sustaining a wildlife population under the influence of time-varying anthropogenic stress is lacking.2. Here, we fill this gap by quantifying the costs of reintroduction as a function of exposure to an environmental stressor and the size of the wildlife population to be maintained. Our approach combines quantitative stressor-response relationships for vital rates (reproduction and survival) with a wildlife demographic model to compute the impacts of the stressor on the size of the target population. Subsequently, cost estimates are obtained by quantifying the number of captive-reared individuals needed per year in order to maintain a user-defined population size, given the exposure to the stressor of concern. We applied our approach to calculate the reintroduction costs required to restore a minimum viable population (MVP) of peregrine falcons (Falco peregrinus) in California over the period 1970-1994, when the population was exposed to the toxicant dichlorodiphenyldichloroethylene.3. Assuming a gradual yearly increase of 150% in the availability of captive-reared young, 1,753 captive-reared young were required to restore and maintain a MVP of 238 adults. The corresponding reintroduction costs were in total ~$3,023,000.Assuming lower reintroduction efforts (in terms of the availability of captivereared young), the projected reintroduction costs decreased by ~33%. However, the population then reached the minimum viable size only 9 years later, thus reflecting a trade-off between costs and population viability. 4. Synthesis and applications. The approach presented in this study ensures an adequate prediction of the costs of maintaining a wildlife population at a user-defined size through reintroduction. It can be applied to any wildlife population in order to obtain the number of individuals and corresponding costs required to sustain a Additional supporting information may be found online in the Supporting Information section. How to cite this article: Hilbers JP, Huijbregts MAJ, Schipper AM. Predicting reintroduction costs for wildlife populations under anthropogenic stress.

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Spatially explicit poisoning risk affects survival rates of an obligate scavenger

Cited by 29 publications

References 53 publications

Assessing the effects of different management scenarios on the conservation of small island vulture populations

Assessing the effects of different management scenarios on the conservation of small island vulture populations

Changes in nesting numbers and breeding success of African White-backed Vulture Gyps africanus in north-central Botswana

Predicting reintroduction costs for wildlife populations under anthropogenic stress

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