IUCN captive management guidelines support ex situ conservation of the Bengal florican Houbaropsis bengalensis blandini
S IMO N P. MAHOOD,CHAMNAN HONG,MIC HAEL MEY E RHOF F,PAU P. F ERR ANDO PHEARUN SUM,VIRAK SON,PENGANN OUCH and STEPHEN T. GAR N E T T
Abstract Ex situ conservation of species is risky and expen- sive, 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 sub- species 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 estab- lishing 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 inter- national 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 con- servation, and documented our plans to mitigate them. Modelling shows that it is unlikely that birds could be re- leased within 20–30 years, by which time genetic, morpho- logical 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 impli- cations 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.
SIMON
P.MAHOOD* (Corresponding author,
orcid.org/0000-0001-9459-1064)
and STEPHEN T. GARNETT (
orcid.org/0000-0002-0724-7060) Research Institute for the Environment and Livelihoods, Charles Darwin University, Ellengowan Drive, Casuarina, Northern Territory 0810, Australia E-mail
simonpeter.mahood@
cdu.edu.au
CHAMNAN HONG* and VIRAK SON* Department of Freshwater Wetland Conservation, Ministry of Environment, Phnom Penh, Cambodia
MICHAEL MEYERHOFF and PAU P. FERRANDO Angkor Centre for Conservation of Biodiversity, Kbal Spean, Cambodia
PHEARUN SUM Wildlife Conservation Society, Phnom Penh, Cambodia
PENGANN OUCH Department of Wildlife and Biodiversity, Forestry Administration, Ministry of Agriculture, Forestry and Fisheries, Phnom Penh, Cambodia
*Also at: Wildlife Conservation Society, Phnom Penh, Cambodia
Received 20 May 2019. Revision requested 9 September 2019. Accepted 21 December 2019. First published online 26 March 2021.
Keywords Bengal florican, bustard, captive management, decision tree, demographic modelling, ex situ conservation, extinction, IUCN guidelines
Supplementary material for this article is available at
doi.org/10.1017/S0030605319001510
Introduction
2011), with 34 animals and 35 plants categorized as Extinct in the Wild and thus relying entirely on persistence of pop- ulations in captivity (IUCN, 2019). Successful case studies include the California condor Gymnogyps californianus in the Americas (Snyder & Snyder, 2000) and crested ibis Nipponia nippon in Asia (Xi et al., 2002). The hope that these examples engender, coupled with the dire situation facing an increasing number of species in the wild (Butchart et al., 2010), manifests in recommendations for captive breeding in the IUCN Red List accounts of 2,199 threatened or Near Threatened species (IUCN Conservation Planning Specialist Group, 2019). However, zoos can conserve only a small proportion of threatened species (Balmford et al., 1996), and the familiarity of successful case studies masks the fact that ex situ management is difficult, risky, time-consuming and financially costly, and can increase the risk of extinction forwild populations by removing individuals fromthe wild to create founder populations (Snyder et al., 1996). A compre- hensive global evaluation of conservation reintroduction, reinforcement or replacement case studies found that 72% of those with a known outcome succeeded and 28% failed; not eliminating the cause of decline was the greatest cause of failure (Bubac et al., 2019). Faced with data that indicate a rapidly declining population, conservation managers must make a timely, informed decision regarding whether or not to proceed with ex situ management (McGowan et al., 2017). A failure to act quickly on available evidence of spe- cies declines can lead to extinctions (Martin et al., 2012), but making the wrong decision can also increase the risk of extinction (Snyder et al., 1996). Management of species occurs along a continuum of
E
states ranging from free-ranging self-sustaining wild popu- lations to species that exist only in captivity (Redford et al.,
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (
http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited. Oryx, 2021, 55(6), 903–915 © The Author(s), 2021. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605319001510
x situ management is increasingly used to prevent species extinctions (Seddon et al., 2007; Redford et al.,
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