Distribution and detectability of mammalian pests in the Waikato Region

ABSTRACT

We used systematic arrays of camera traps combined with site-occupancy analyses to estimate the site-specific presence and probability of detection the principal target pests across the three main habitats of Waikato Region, classified by season. Cameras easily identified brushtail possums, hedgehogs, ship rats, wild house mice, and mustelids, i.e., stoats, feral ferrets and weasels taken as a group. The data comprise four sets of estimates, one set of 15 (five targets, three habitats) for each season of the year, total of 60. Of these, only 10 (17%) returned probabilities of detection of more than 50% for that species in that habitat at that season, given that at least one individual was present then. All pest species we monitored were present on pastoral land. Pasture makes up more than half of the land cover of the Waikato, so it supports large numbers even of species that are not abundant in that habitat. Hence, pest control operations intended to conserve indigenous species in protected forests need to allow for the important effects of rapid reinvasions of controlled areas from adjacent pasture.

KEYWORDS:

• Pest management
• distribution surveys
• detection failure
• camera traps
• site-occupancy analyses

Acknowledgements

The authors thank Bruce Patty (University of Waikato) and Dave Byers and Nicholas Singers (Waikato Regional Council), for assistance and funding in obtaining cameras and help with selecting appropriate study areas. See https://www.waikatoregion.govt.nz/community/about-the-waikato-region/. The authors also thank Goodnature Limited (Wellington) and Dr Christine Stockum of their research staff, for providing supplies of bait and detector cards. The authors thank David Yang, DoC, Fraser Storey, George Connelly, Nico van der Schyff, Robert Schoonderwoerd, Susan and Wallace Hall and Wayne Buckley, for granting access to their land, and Petrus and Sandra Breedt, for transport.

Disclosure statement

No potential conflict of interest was reported by the author(s).