Somewhat saved: a captive breeding programme for two endemic Christmas Island lizard species, now extinct in the wild P AUL A NDREW,HAL C OGGER,DON D RISCOLL,SAMANTHA F LAKUS,PETER H ARLOW D ION M APLE,MIKE M ISSO,CAITLIN P INK,KENT R ETALLICK,KARRIE R OSE B RENDAN T IERNAN,JUDY W EST and J OHN C.Z. WOINARSKI Abstract As with many islands, Christmas Island in the or diseases, or to other environmental modifications. Indian Ocean has suffered severe biodiversity loss. Its terres- Consequently, island species are over-represented among trial lizard fauna comprised five native species, of which four the world’s recent extinctions (Duncan & Blackburn, ). were endemic. These were abundant until at least the late In many cases, conservation management responses for s, but four species declined rapidly thereafter and were island species have been ineffective. Often, resources have last reported in the wild between and . In response been inadequate to respond to synchronous declines of to the decline, a captive breeding programme was established many species. On many islands there are multiple threats in August . This attempt came too late for the Christmas and it is difficult to disentangle their relative or synergistic Island forest skink Emoia nativitatis,whoselastknownindi- impacts, and hence to target management responses most vidual died in captivity in , and for the non-endemic effectively. Furthermore, there may be limited options for coastal skink Emoia atrocostata. However, two captive popu- in situ conservation, and many threats may be difficult to lations are now established for Lister’sgeckoLepidodactylus control (Fritts & Rodda, ). listeri and the blue-tailed skink Cryptoblepharus egeriae.The The Australian Indian Ocean territory of Christmas conservation future for these two species is challenging: re- Island has high levels of endemism but many of these en- introduction will not be possible until the main threats are demic species have declined or become extinct. For example, identified and controlled. of five native mammal species, at least four of which were endemic, only the Christmas Island flying-fox Pteropus Keywords Christmas Island, extinction, gecko, Indian (melanotus) natalis, is known to be extant, and it is now Ocean, reintroduction, skink Critically Endangered (Woinarski et al., ). Notably, the Christmas Island pipistrelle Pipistrellus murrayi was abundant up to the s but declined rapidly to extinction slands provide many of the world’s most important con- in . The failure to conserve this species has been the servation opportunities and challenges. Many have a high I subject of critical review (Martin et al., ). complement of endemic species but these often have small Christmas Island is a km island in the Indian Ocean populations, limited genetic diversity and low reproductive (°′ S, °′ E), km distant from the nearest land rates, lack immunity to novel diseases or are predator-naive. (Java, Indonesia). It was settled in the s, for phosphate These characteristics mean that island species have little mining; % of the island has been cleared but it has otherwise resilience to introduced predators, consumers, competitors mostly retained its original rainforest, and %isnationalpark. Many species have been introduced to Christmas Island and are now widespread even in intact native vegetation. PAUL ANDREW,PETER HARLOW and KARRIE ROSE Taronga Conservation Society Australia, Bradleys Head Road, Mosman, New South Wales, Australia Across much of the island super-colonies of the introduced yellow crazy ant Anoplolepis gracilipes have subverted the HAL COGGER Australian Museum Research Institute, Sydney, New South Wales, Australia previous crab-mediated ecology, leading to an ‘invasional ’ ’ DON DRISCOLL School of Life and Environmental Sciences, Deakin University, meltdown (O Dowd et al., ). The abundance of yellow Burwood, Victoria, Australia crazy ants has been periodically controlled through broad- SAMANTHA FLAKUS,DION MAPLE,MIKE MISSO,CAITLIN PINK,KENT RETALLICK and scale application of insecticides. BRENDAN TIERNAN Parks Australia, Christmas Island, Indian Ocean, Australia Introduced species known or presumed to prey upon JUDY WEST Department of the Environment, Parks Australia, Canberra, Christmas Island lizards include the feral cat Felis catus (in- Australian Capital Territory, Australia troduced in the s), black rat Rattus rattus (), giant JOHN C. Z. WOINARSKI (Corresponding author) Threatened Species Recovery centipede Scolopendra subspinipes (s) and wolf snake Hub, Charles Darwin University, Casuarina, Northern Territory 0909, Australia. E-mail [email protected] Lycodon capucinus (c. ). All are now common across Received July . Accepted September . First published online the island. An eradication programme is being implemented November . for feral cats, but no broad-scale management for the other Oryx, 2018, 52(1), 171–174 © 2016 Fauna & Flora International doi:10.1017/S0030605316001071 Downloaded from https://www.cambridge.org/core. IP address: 170.106.202.58, on 28 Sep 2021 at 07:45:25, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0030605316001071 172 P. Andrew et al. predators has been undertaken. Three lizard species that may be potential competitors to and disease vectors for na- tive reptiles have been introduced: the geckoes Hemidactylus frenatus (first recorded in ) and Gehyra mutilata () and skink Lygosoma bowringii (). The reptile fauna comprised six native species: the endemic Christmas Island blind snake Ramphotyphlops exocoeti,the Christmas Island forest skink Emoia nativitatis, the blue- tailed skink Cryptoblepharus egeriae, the giant gecko Cyrtodactylus sadleiri and Lister’sgeckoLepidodactylus listeri, and the non-endemic coastal skink Emoia atrocostata. The blue-tailed skink (snout–vent length c. mm) FIG. 1 Changes in the size of captive-breeding populations of forages actively in low vegetation or on the ground. ’ ’ blue-tailed skink Cryptoblepharus egeriae and Lister s gecko Lister s gecko (c. mm) is nocturnal and arboreal. The for- Lepidodactylus listeri from November to May on est skink (c. mm) occurred mostly in forest gap and edge Christmas Island and at Taronga Zoo. habitats. The coastal skink (c. mm) occurred mainly in rocky littoral habitats (Cogger et al., ). Although there are only six records of the blind snake geckoes and blue-tailed skinks (at November ) were since (Maple et al., ), the five lizards were generally maintained at facilities on Christmas Island. common until at least (Cogger et al., ). Declines of These have been treated as independent units (i.e. without the blue-tailed skink were first reported in (Rumpff, interchange of individuals after establishment). Management ) and of the forest skink, coastal skink and Lister’s by Mean Kinship (Ballou & Lacy, ) was used to maximize gecko in (Cogger & Sadlier, ), with ongoing de- retention of genetic diversity for Lister’sgeckoatTaronga, clines reported between and (James, ; and management by Maximal Avoidance of Inbreeding Schulz & Barker, ). For reasons not yet understood, (Princée, ) was used for blue-tailed skinks at both sites, the giant gecko remains abundant and widespread. and for Lister’s gecko at Christmas Island. Detailed husband- In response to the decline of four lizard species, a captive ry information is not presented here. breeding programme was initiated in . Here we describe Captive populations have been monitored since the progress and outlook of this programme. The role and November ; they have been stable at Taronga, and cost-effectiveness of captive breeding within a broader con- have increased on Christmas Island (Fig. ). These results servation context has been a focus of considerable global provide evidence of some success, but what are the local interest (Bowkett, ). In this case, it was justified by the and broader contexts of this programme, and how can rapid declines (Smith et al., ) and the likelihood that this limited success be consolidated? threats could not be controlled in the wild in the short time Reptiles are currently undergoing a severe global decline, period before the probable extinction of these species. Despite with increasing numbers of threatened species and extinc- a series of intensive and extensive searches, the last records of tions (Gibbons et al., ). Loss is particularly pronounced the Christmas Island population of coastal skink were in for species with small ranges, especially island species. September , of the forest skink and blue-tailed skink in Increasingly, captive breeding and translocation are likely August , and of Lister’s gecko in October . to be necessary mechanisms to forestall extinctions for the From August as many individuals as possible of the most threatened species. The Christmas Island lizards pre- four declining species were collected from the wild. Three sent a sobering example. The five species were abundant and forest skinks (all females), Lister’s geckoes and blue- presumed secure in (and perhaps remained so for at tailed skinks were captured and housed in purpose-built fa- least another decade), having withstood nearly years cilities. No coastal skinks and no male forest skinks could be of human settlement and many introductions. But by captured. The last of the three forest skinks died on May four of these species had disappeared from the wild. The , the presumed extinction date for this species. The conservation response