Ex 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.