ReviewDistribution and conservation status of the orang-utan (Pongo spp.) on Borneo and Sumatra: how many remain? S e r g e A . W i c h , E r i k M e i j a a r d , A n d r e w J . M a r s h a l l , S i m o n H u s s o n M a r c A n c r e n a z , R o b e r t C . L a c y , C a r e l P . v a n S c h a i k , J i t o S u g a r d j i t o T o g u S i m o r a n g k i r , K a t h y T r a y l o r -H o l z e r , M a t t D o u g h t y J a t n a S u p r i a t n a , R o n a D e n n i s , M e l v i n G u m a l , C h e r y l D . K n o t t a n d I a n S i n g l e t o n Abstract In recognition of the fact that orang-utans (Pongo spp.) are severely threatened, a meeting of orangutan experts and conservationists, representatives of national and regional governmental and non-governmental organizations, and other stakeholders, was convened in Jakarta, Indonesia, in January 2004. Prior to this meeting we surveyed all large areas for which orang-utan population status was unknown. Compilation of all survey data produced a comprehensive picture of orang-utan distribution on both Borneo and Sumatra. These results indicate that in 2004 there were c. 6,500 P. abelii remaining on Sumatra and at least 54,000 P. pygmaeus on Borneo.Extrapolating to 2008 on the basis of forest loss on both islands suggests the estimate for Borneo could be 10% too high but that for Sumatra is probably still relatively accurate because forest loss in orang-utan habitat has been low during the conflict in Aceh, where most P. abelii occur. When those population sizes are compared to known historical sizes it is clear that the Sumatran orang-utan is in rapid decline, and unless extraordinary efforts are made soon, it could become the first great ape species to go extinct. In contrast, our results indicate there are more and larger populations of Bornean orang-utans than previously known. Although these revised estimates for Borneo are encouraging, forest loss and associated loss of orang-utans are occurring at an alarming rate, and suggest that recent reductions of Bornean orang-utan populations have been far more severe than previously supposed. Nevertheless, although orang-utans on both islands are under threat, we highlight some reasons for cautious optimism for their long-term conservation.

Tigers (Panthera tigris) are disappearing rapidly from the wild, from over 100,000 in the 1900s to as few as 3000. Javan (P.t. sondaica), Bali (P.t. balica), and Caspian (P.t. virgata) subspecies are extinct, whereas the South China tiger (P.t. amoyensis) persists only in zoos. By contrast, captive tigers are flourishing, with 15,000-20,000 individuals worldwide, outnumbering their wild relatives five to seven times. We assessed subspecies genetic ancestry of 105 captive tigers from 14 countries and regions by using Bayesian analysis and diagnostic genetic markers defined by a prior analysis of 134 voucher tigers of significant genetic distinctiveness. We assigned 49 tigers to one of five subspecies (Bengal P.t. tigris, Sumatran P.t. sumatrae, Indochinese P.t. corbetti, Amur P.t. altaica, and Malayan P.t. jacksoni tigers) and determined 52 had admixed subspecies origins. The tested captive tigers retain appreciable genomic diversity unobserved in their wild counterparts, perhaps a consequence of large population size, century-long introduction of new founders, and managed-breeding strategies to retain genetic variability. Assessment of verified subspecies ancestry offers a powerful tool that, if applied to tigers of uncertain background, may considerably increase the number of purebred tigers suitable for conservation management.

Short running title (<45 characters including spaces)IUCN ex situ management guidelines up to 10 keywords listed alphabetically for indexing purposes (It is essential that the keywords be chosen carefully to assist in the choice of appropriate editors and referees.) captive management, conservation decision-making, ex situ management, intensive management, population management, strategic planning, threatened species, Type of article Policy perspectiveNumber of words in the abstract and in the manuscript as a whole 197 words in Abstract 2879 (introduction to end of Discussion); 3236 (Abstract to end of Acknowledgements) Number of references 32 AbstractThe Convention on Biological Diversity's target of halting extinctions by 2020 is less than a handful of years away. Captive, or ex situ, management has long been cited as having a potential role to play in the recovery of species, although this remains the subject of debate. IUCN's Species Survival Commission (IUCN SSC) produced guidelines to assist in identifying when ex situ management may contribute to species recovery in 2002. Since then, there have been considerable developments in a range of areas that may influence the design of such programmes (e.g. understanding of constraints o breeding programmes, development of new techniques and approaches, and strategic planning approaches to species conservation). IUCN SSC has therefore revised its guidance and proposes a five step process: 1) Compile a status review; 2) Define the role(s) that ex situ management might play; 3) Determine the precise nature of the ex situ population in order to meet identified role(s); 4) Define resources and expertise, and appraise the feasibility and risks; and 5) Make a decision that is informed based on the above analysis and transparent. These guidelines offer an objective process for considering the role of ex situ management in species conservation.

Zoos and other ex situ wildlife institutions can play an important role in species conservation by maintaining populations for education and research, as sources for potential re-introduction or reinforcement, and as ambassadors for financial support of in situ conservation. However, many regional zoo associations are realizing that current captive populations are unsustainable, with many programs failing to meet demographic and genetic goals to ensure long-term viability. Constraints on population size due to limited space often mandate delayed and/or less frequent breeding, but for females of many species this can have profound effects on fertility. A retrospective analysis combined with published literature and reliable anecdotal reports reveals that, when females are housed in a non-breeding situation for extended periods of time, reproductive changes that negatively impact fertility have occurred in multiple species, including canids, elephants, white rhinoceros, Seba's bats, wildebeest, stingrays, and some felid species. Competing space needs and changing interest in taxa for exhibits over time compound the problem. Counter strategies to breed early and often have their own demographic and genetic consequences as well as logistical and political implications. Strategies to mitigate the sustainability crisis in these taxa might include a mixed strategy in which young, genetically valuable females are bred earlier and at more regular intervals to ensure reproductive success, in combination with the judicious use of available tools to manage the number of offspring produced, including contraception and culling. An understanding of the issues at stake is the first step towards developing management strategies for sustainable populations.

Captive populations are managed to promote demographic growth or stability and preserve genetic variation. Current protocols use survival rates to estimate the number of offspring needed to achieve target population size, while pedigree analysis is used to select breeding pairs to retain genetic diversity and minimize inbreeding. Despite these efforts, many captive populations fall short of programme goals. Reproductive failure of breeding pairs is a contributing factor, often as a result of pair incompatibility. Because choice is a component of most mating systems, providing a choice of mates could improve the sustainability of captive populations through increased fecundity and offspring survival while enhancing animal well‐being. However, allowing mate choice might undermine genetic goals if those choices are inconsistent with genetic management objectives. Strategies for incorporating mate choice into management include: (1) using mate choice to increase reproduction of genetically valuable animals; (2) providing multiple genetically acceptable mates; (3) assessing mate preferences via odour or other cues before animal transfer; (4) using alternate breeding strategies, such as specialized breeding centres. Research is needed to determine whether incorporation of mate choice in breeding programmes can increase reproductive success without compromising genetic health and the potential to contribute to the conservation of wild populations.