Norway rats (Rattus norvegicus) have populated Campbell Island in the New Zealand subantarctic for nearly 200 years. During this time they, in combination with feral cats which have since died out, have had a devastating effect on the island’s fauna, marooning several species of bird to the small rat-free islands around the coast and probably causing the extinction of several other undiscovered species. At 11,300 ha the attempt to eradicate rats from Campbell Island will be the largest ever undertaken. The island’s size coupled with its location in the furious fifties (700 km south of the New Zealand mainland) renowned for their strong winds and frequent rainstorms, means the attempt will be stretching the boundaries of current technology. In order to make the eradication logistically feasible, the margin for error that has been build into all previous eradications has had to be significantly reduced. Instead of two bait drops totalling 12kg/ha as is usually used, Campbell will be done with a single drop, but with a 50% overlap to eliminate the risk of gaps, totalling 6 kg/ha. This technique was tested in 1999 with a 600ha field trial carried out on the island. Rhodamine dye showed that all the rats in the baited area ate bait and would therefore have been killed.
|Author||McClelland, P. J.|
|Secondary title||International Conference on Eradication of Island Invasives|
|Publisher||IUCN Invasive Species Specialist Group|