Continuous monitoring of predator control operations at landscape scale


  • Carolyn M. King,

  • Roderick M. McDonald,

  • Ross D. Martin,

  • Darryl I. MacKenzie,

  • Grant W. Tempero,

  • Selena J. Holmes

  • Carolyn King is a senior lecturer in the Department of Biological Sciences, University of Waikato (Private Bag 3105, Hamilton 3240, New Zealand; Fax: +64 7838 4324; Email:; Rod McDonald is an engineer and Selena Holmes is a technician at HortResearch (Private Bag 3123, Hamilton 3240, New Zealand; Email:;; Ross Martin is a technical officer at the Department of Conservation, Tongariro Taupo Conservancy (Private Bag, Turangi 3353, New Zealand; Email:; Darryl MacKenzie is a consultant biometrician and cofounder of Proteus Research & Consulting Ltd (PO Box 5193, Dunedin, New Zealand; Email:; and, Grant Tempero is a PhD student at the Department of Biological Sciences, University of Waikato (Private Bag 3105, Hamilton 3240, New Zealand; Email: At the time of this project, five of the authors were members of a team based at HortResearch working on the development of smart automated bait dispensers for pest control. Darryl MacKenzie was commissioned by the team to apply his specialist knowledge of the program presence to analyse the results.


Summary  Exotic predators are considered pests to wildlife and agriculture, requiring predator-control programs. Effective monitoring of predator-control operations is essential to justify their considerable cost, but often impossible in practice. The difficulties are especially severe if the target species is small and wide-ranging, and the area to be protected is inaccessible and/or extensive. A convenient model predator of this type, the feral Ferret (Mustela furo), is subject to control on farmland in New Zealand. We monitored the distribution of Ferrets over 2400 ha in the central North Island, before and throughout a standard control operation by professional trappers. We used 24 units of a new automated monitoring device, the Scentinel, set in a grid at 1 per 100 ha. Over 11 weeks (11 February to 29 April 2005, 1718 trap nights), we recorded 1559 visits by small mammals, including 198 by Ferrets. By the end of the 4th week, Ferrets had been detected at 17 of 24 sites. Removal of Ferrets from the study area by contractors began during the 5th week, and was reflected in significant declines in the number of Ferret visits recorded per day (P = 0.008) and the number of sites visited (P = 0.021). Analysis of our extensive repeat-survey data by site-occupancy methods confirmed these trends in greater detail, while also allowing for variation in detectability.