Trial translocations of the blue-tailed skink to Christmas Island and the Cocos (Keeling) Islands

Date: 28, Sep, 2021
Author(s):   Jon-Paul Emery, Kristen Schubert

The threatened blue-tailed skink (Cryptoblepharus egeriae) is endemic to Christmas Island and is listed as Extinct in the Wild by the IUCN. We trialled two reintroductions of the blue-tailed skink on Christmas Island, and two assisted introductions of the blue-tailed skink on the Cocos (Keeling) Islands of Pulu Blan and Pulu Blan Madar. The initial trial on Christmas Island failed possibly due to predation from introduced giant centipedes and inappropriate habitat quality. We eradicated centipedes and improved the habitat prior to the second more successful reintroduction. The assisted introduction trials to Pulu Blan and Pulu Blan Madar resulted in significantly different survival rates in the first 12-months post release. On Pulu Blan the skinks have established within preferred habitat and continued to increase, whilst the population on Pulu Blan Madar rapidly declined immediately after release. Christmas Island National Park intervened, baiting the island targeting yellow crazy ants, and at 12-months post-release the population had increased. Our research shows that if blue-tailed skinks can establish; they can breed, forage for food and undergo rapid population growth. Our early results suggest that translocations can be used to increase the conservation status of this species; however, longterm success cannot be guaranteed. Ongoing research on early detection and control of introduced predators is critical for ongoing success.