Gecko threat to Christmas Island

Sri Lankan house gecko | Invasive species can bring new diseases that could threaten native reptiles

A new invasive species of gecko has been discovered in the Cocos (Keeling) islands, and it’s got our Parks Australia staff worried. Two Sri Lankan house geckos (Hemidactylus parvimaculatus) have been found on West Island - the first time this gecko has been found anywhere in Australia.

The gecko hasn’t spread to Pulu Keeling National Park and it isn’t a problem in the southern atoll, because there aren’t any endemic geckos on the Cocos Islands. However, if this recent invader were to reach Christmas Island or the Australian mainland, it could be a big threat to native reptiles. Invasive geckos tend to be much more aggressive than our native ones, competing for food and habitat.

On Christmas Island we’ve already seen the damage invasive geckos can do. The invasive Asian house gecko arrived on Christmas Island in the 1940s. In combination with other threats, it has had a devastating effect on Christmas Island’s native reptiles, and we have had to embark on an expensive captive breeding program to save them.

Our captive population of Lister's gecko are the last animals protecting this species from extinction

From the results of our recent surveys, it is thought that only one native gecko, the giant gecko, remains in the wild on Christmas Island. Our other native gecko, Lister’s gecko, survives only in captivity. Both of these species are found nowhere else in the world and we hope that the Lister’s gecko can one day be reintroduced back into its native habitat. However, if another invasive gecko were to take hold on Christmas Island, it could tip the balance for the giant gecko and make it all but impossible for us to successfully reintroduce the Lister’s gecko to the wild.

We’re working with our partner agencies and the community to try and stop the spread of this threat. We’ll be keeping a sharp eye out in Christmas Island National Park, in case the Sri Lankan house gecko has hitched a ride over in sea freight cargo or commercial or freight aircraft.

Sam Flakus, Christmas Island National Park