Landcare Research - Manaaki Whenua

Landcare-Research -Manaaki Whenua

Animal selfies ... an effective pest monitoring strategy

Published: 30 October 2014 - by Al Glen



Currently there are few robust techniques for measuring the results of pest control targeting predatory mammals such as stoats, feral cats and hedgehogs.

Al Glen, Bruce Warburton, Jennyffer Cruz and Morgan Coleman (all at our Lincoln site) tested the effectiveness of camera traps at detecting these species at two sites — Macraes Flat (eastern Otago) and Tasman Valley (upper Waitaki basin) where DOC conducts intensive predator trapping. 

At each site, Al and his colleagues set 30 cameras at 500-m intervals alongside tracks used to service the kill traps; then compared capture rates of camera traps and kill traps and the percentage of devices that detected each species. Camera traps detected all three target species (plus various non-target animals), with the cameras recording more cats and hedgehogs than kill traps. Comparisons for stoats were inconclusive because there wasn’t enough data.

The researchers also modelled the effect of using fewer cameras, and concluded a minimum of 20 cameras is essential for monitoring cats and hedgehogs. Previous pen trials by Al had identified the optimal specifications for cameras (e.g., trigger speed; passive infrared sensor; infrared flash). While inexpensive ‘off-the-shelf’ models are not necessarily recommended, expensive cameras may have many superfluous features for this purpose.  Al thinks that by using quality components, simple but relatively inexpensive cameras could be produced specifically for monitoring purposes, especially as camera traps show promise as a cheap and effective monitoring method for assessing the effectiveness of pest mammal control operations in New Zealand.


Glen AS, Warburton B, Cruz J, Coleman M 2014. Comparison of camera traps and kill traps for detecting mammalian predators: a field trial. New Zealand Journal of Zoology 41(3): 155–160.

Glen A, Warburton B, Ekanayake J, Nichols M,  Cockburn S 2013. Camera traps for monitoring cat, stoat and hedgehog populations. Kararehe Kino 22: 9.

Glen AS, Cockburn S, Nichols M, Ekanayake J,  Warburton B 2013. Optimising camera traps for monitoring small mammals. PLoS ONE 8: e67940.


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