Document ID: chunk:federal_register_of_legislation:F2006L03939:body:0:p5
Version: federal_register_of_legislation:F2006L03939
Segment Type: other
Provision Reference: 
Character Range: 12290–15312

roads and tracks, may also have had impacts on Lister's Gecko and the blind snake. The impacts of such intrusions into forests are usually greater than the actual areas excised, due to degraded edges being used by introduced species that are competitors or predators, and by changing forest micro-climate significantly.

Probably the greatest impact on the ecology of the island, including the National Park, has been the development of supercolonies of the crazy ant, whose activities have seriously degraded about half of the forested habitats, and resulted in massive mortalities of terrestrial crabs and other organisms, that have led in turn to gross deleterious structural and floristic changes in the island's forests (Green et al., 2001). On-going control of the crazy ant and rehabilitation of the affected forests is probably critical to the survival of the endemic reptiles, including Lister's Gecko and the blind snake.

Information gaps
Knowledge of the biology, ecology, habitat preferences and spatial distribution of Lister's Gecko and the Christmas Island Blind Snake is insufficient to inform specific recovery actions. Consequently priority must be given to locating and determining relative abundance of any remaining populations through survey and monitoring, then targeted research on the species' ecologies. Interim actions are aimed at maintaining the ecological integrity of known or suspected habitats and determining the likelihood of impacts of potential threats.

New invasive species
A number of exotic species have been previously introduced to Christmas Island, including the crazy ant, black rats and cats, and more recently the scincid lizard, Lygosoma bowringii (sometime before 1979) and the Wolf Snake (ca. 1983). The probability of introduction of the invasive gecko Lepidodactylus lugubris (a congener of Lister's Gecko) is high and could possibly lead to eradication of any remaining populations of the latter should it become established on Christmas Island. The colonisation of Christmas Island by the latterly introduced species represents a failure, at the time of entry, of quarantine mechanisms then in place, and are indicative of the special vulnerability of isolated oceanic islands to the impacts of exotic species. The exclusion of further exotic species may be a critical factor in maintaining remaining populations of Christmas Island's native and endemic biota.

Disease
There is currently no evidence to suggest that exotic pathogens may be all or partly responsible for the recorded declines (Cogger et al., 1983; James, 2004) in the endemic reptiles of Christmas Island, including Lister's Gecko. However, this is a possibility that cannot be currently tested or dismissed. Without locating and regularly monitoring any remaining populations, as proposed in this Recovery Plan, pathogenic mortalities have little chance of being identified.

Competition
The introduced geckos Hemidactylus frenatus and Gehyra mutilata are both arboreal and feed on small arthropods,