Somewhat saved: a captive breeding programme for two endemic Christmas Island lizard species, now extinct in the wild

Abstract

As with many islands, Christmas Island in the Indian Ocean has suffered severe biodiversity loss. Its terrestrial lizard fauna comprised five native species, of which four were endemic. These were abundant until at least the late 1970s, but four species declined rapidly thereafter and were last reported in the wild between 2009 and 2013. In response to the decline, a captive breeding programme was established in August 2009. This attempt came too late for the Christmas Island forest skink Emoia nativitatis, whose last known individual died in captivity in 2014, and for the non-endemic coastal skink Emoia atrocostata. However, two captive populations are now established for Lister's gecko Lepidodactylus listeri and the blue-tailed skink Cryptoblepharus egeriae. The conservation future for these two species is challenging: reintroduction will not be possible until the main threats are identified and controlled.

Endemic species of Christmas Island, Indian Ocean

“…The Christmas Island pipistrelle Pipistrellus murrayi remained abundant and apparently secure up to at least the 1980s but declined rapidly thereafter, culminating in extinction in 2009 (Martin et al 2012;Woinarski 2018). Likewise, three of the four endemic lizards, and another native but not endemic lizard, were also abundant in the 1980s, but became extinct or extinct in the wild by 2012 (Smith et al 2012;Andrew et al 2018). For some of these vertebrates, the rapidity of loss outstripped the pace of formal recognition as threatened.…”

“…For example, the Christmas Island forest skink Emoia nativitatis was first listed as a threatened species in 2010 (at global scale) and January 2014 (nationally). This was at about the time or after its extinction in the wild in 2010 and shortly before the 2014 death of the last of three individuals collected in the hope of establishing a captive breeding program (Andrew et al 2018). The belated listing was notwithstanding substantial evidence over several decades of severe decline (Smith et al 2012).…”

“…Emoia nativitatis is now extinct, and Lepidodactylus listeri and Cryptoblepharus egeriae are extinct in the wild. The Christmas Island population of Emoia atrocostata was also extirpated over this period (Andrew et al 2018).…”

“…All five endemic reptile species are considered threatened at global and national levels (Table 1), having exhibited severe and rapid decline since the 1980s (Smith et al 2012;Andrew et al 2018). Emoia nativitatis is now extinct, and Lepidodactylus listeri and Cryptoblepharus egeriae are extinct in the wild.…”

“…As a consequence of these detrimental factors, there has been a very high rate of loss of endemic vertebrates, including the extinction of at least three and probably four of the island's five endemic mammal species (Wyatt et al 2008;Woinarski et al 2017) and the recent (since 2009) extinction (or extinction in the wild) of three of its four endemic lizard species (Smith et al 2012;Andrew et al 2018). This gives reasonable grounds for concern that endemic species in less well-known groups might have become extinct, or are now highly imperilled, with such loss and decline going unnoticed.…”