New Zealand Journal of Ecology (2011) 35(3): 236- 246

Accuracy and precision of skink counts from artificial retreats

Research Article
Marieke Lettink 1*
Colin F.J. O’Donnell 2
Joanne M. Hoare 2
  1. Fauna Finders, 176 Mt Pleasant Road, Christchurch 8081, New Zealand
  2. Research & Development Group, Department of Conservation, PO Box 13049, Christchurch 8141, New Zealand
*  Corresponding author

Index counts are commonly used to detect spatial and temporal changes in the size of wildlife populations. For indices to be valid there must be a constant (usually linear) relationship between the index and population size. In a study conducted in the Eglinton Valley (Fiordland, South Island, New Zealand), single-day index counts of common skinks (Oligosoma polychroma) from artificial retreats were compared with capture–mark–recapture (CMR) estimates of population size (Nˆ) obtained by pitfall trapping. Generalised linear models revealed that skink counts from artificial retreats provided a reasonably accurate (P P –1, which was high compared with other common skink populations. We recommend: (1) long-term monitoring of common skinks in the Eglinton Valley, using the index method described herein; (2) calibration of index counts against population size estimates collected from other habitats and species.