Distribution and Activity of Small Mammals on Pastoral Farmland and Forest in New Zealand

We monitored the distribution and activity of small mammals on central North Island farmland continuously for 11 weeks in late summer and autumn 2005, using an automated monitoring device, the Scentinel . Between 11 February and 29 April 2005 (1718 trap-nights, 1559 visits by small mammals), we documented extensive spatial and temporal variation in distribution and activity of small mammals. Hedgehogs (Erinaceus europaeus) and rats (Rattus rattus) were strictly nocturnal; ferrets (Mustela furo) were mostly nocturnal, and feral cats (Felis catus) were indifferent. The disappearance of ferrets during a standard control programme was well represented. Records of rats suddenly increased in early April, coinciding both with the removal of ferrets and with the maize harvest, which reduced cover in the fields. We repeated the trial with six Scentinels set in mixed podocarp/hardwood forest for 5 weeks in mid winter. Most (82%) visits recorded between 26 May and 20 June 2005 (198 trap-nights, 690 visits by small mammals) were by rats, all strictly nocturnal, but 9 visits by stoats (Mustela erminea) were all diurnal.