Context. The importance of oceanic islands in terms of conservation of native species is often affected by the introduction of invasive species. Introduced mammalian predators such as feral cats (Felis catus) and rats (Rattus sp.), have been responsible for population decline and extinction of many native species on oceanic islands worldwide. Christmas Island, located in the Indian Ocean, is an example of how introduced mammals have influenced the population of endemic species even to the point of extinction. Aims. The aim was to monitor the effect of a baiting program for rats as part of the management plan for feral cats and rats conducted on the island since 2010 by the Department of Environment and Conservation. Methods. Twenty rats (ten in each site) were trapped in two study sites (Settlement and Upper Poon Saan). Rats were radio collared and released, and then bait stations were opened containing Racumin paste sprayed with coconut milk as an additive. Key results. The baiting had a mean efficacy of 76.5%, with a significant difference (χ2 = 4.650, 1df, P=0.031) observed between the sites (100% at Settlement area and 55.55% at Upper Poon Saan). The mean time of action for the baits for both sites was 5.6 ± 0.6 days and the total mean bait consumption per bait station was 41.6 ± 9.07 g. Conclusions. The results of this study suggest that the type of bait currently in use is adequate but the bait spacing may not be sufficient to control rats successfully on Christmas Island. Implications. It is recommended to place the bait stations without bait in advance so the structure looks familiar to rats in order to avoid bait shyness. It is also recommended to clean up and to remove the rubbish in order to reduce the habitat for rats to aid the control program.
|Publication status||Unpublished - 2012|