Abstract
AbstractEx situ conservation of species is risky and expensive, but it can prevent extinction when in situ conservation fails. We used the IUCN Guidelines on the Use of Ex Situ Management for Species Conservation to evaluate whether to begin ex situ conservation for the South-east Asian subspecies of Bengal florican Houbaropsis bengalensis blandini, which is predicted to be extinct in the wild within 5 years. To inform our decision, we developed a decision tree, and used a demographic model to evaluate the probability of establishing a captive population under a range of husbandry scenarios and egg harvest regimes, and compared this with the probability of the wild population persisting. The model showed that if ex situ conservation draws on international best practice in bustard husbandry there is a high probability of establishing a captive population, but the wild population is unlikely to persist. We identified and evaluated the practical risks associated with ex situ conservation, and documented our plans to mitigate them. Modelling shows that it is unlikely that birds could be released within 20–30 years, by which time genetic, morphological and behavioural changes in the captive population, combined with habitat loss and extinction of the wild population, make it unlikely that Bengal florican could be released into a situation approximating their current wild state. We considered the philosophical and practical implications through a decision tree so that our decision to begin ex situ management is not held back by our preconceived notions of what it means to be wild.
Highlights
Ex situ management is increasingly used to prevent species extinctions (Seddon et al, ; Redford et al, ), with animals and plants categorized as Extinct in the Wild and relying entirely on persistence of populations in captivity (IUCN, )
The group decided to proceed with ex situ management of the Bengal florican, despite the risks, because of rapid, and potentially accelerating, declines in the wild population, the likelihood that threats could not be controlled in the wild before the taxon was rendered extinct, and the relatively high probability of establishing a captive population (Fig. )
Given the numbers of individuals available to be taken into captivity, and differences in selective pressure between captive and wild birds, it is inevitable that captive populations will differ from those in the wild (Frankham, ; Robert, ) even with careful genetic management of the captive flock (Williams & Hoffman, ; Witzenberger & Hochkirch, )
Summary
Ex situ management is increasingly used to prevent species extinctions (Seddon et al, ; Redford et al, ), with animals and plants categorized as Extinct in the Wild and relying entirely on persistence of populations in captivity (IUCN, ). Successful case studies include the California condor Gymnogyps californianus in the Americas (Snyder & Snyder, ) and crested ibis Nipponia nippon in Asia (Xi et al, ). The hope that these examples engender, coupled with the dire situation facing an increasing number of species in the wild (Butchart et al, ), manifests in recommendations for captive breeding in the IUCN Red List accounts of , threatened or Near Threatened species (IUCN Conservation Planning Specialist Group, ). A failure to act quickly on available evidence of species declines can lead to extinctions (Martin et al, ), but making the wrong decision can increase the risk of extinction (Snyder et al, )
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