Wildlife Research Wildlife Research Society
Ecology, management and conservation in natural and modified habitats

Increasing the target-specificity of the M-44 ejector by exploiting differences in head morphology between foxes and large dasyurids

Evelyn Nicholson A and Frank Gigliotti B
+ Author Affiliations
- Author Affiliations

A Wildlife Ecology Research Group, School of Biological Sciences, Monash University, Clayton, Vic. 3800, Australia.

B Vertebrate Pest Research Unit, Department of Primary Industries, PO Box 48, Frankston, Vic. 3199, Australia.

Wildlife Research 32(8) 733-736 https://doi.org/10.1071/WR05015
Submitted: 15 February 2005  Accepted: 28 September 2005   Published: 20 December 2005


The M-44 ejector (ejector) is a more target-specific means of lethal control of red foxes (Vulpes vulpes) than conventional meat baits, which may expose a wide range of non-target species to the bait toxicant. Owing to the threshold pulling force required to activate the ejector, undesired exposure is eliminated in many smaller animals that cannot generate this force. However, the spotted-tailed quoll (Dasyurus maculatus) and the Tasmanian devil (Sarcophilus harrisii) remain potential non-target species because of their larger size. In this study, we report on the development of a collar that excludes devils and quolls by exploiting differences in their head morphology relative to that of red foxes. The collar potentially prevents bait removal by larger non-target species, while still allowing all adult foxes access to the bait to trigger the ejector mechanism. Spotted-tailed quolls small enough to access the bait are theoretically too small to trigger the ejector mechanism set at a threshold pulling force of 2.7 kg.


We thank Clive Marks (Nocturnal Wildlife Research Pty Ltd) for his continuous support and assistance in writing this paper. Staff of the Vertebrate Pest Research Unit (Frankston) provided many valuable suggestions during the development of the collar. The Queen Victoria Museum and the Nature Conservation Branch (Department of Primary Industry, Water and Environment) supplied the study animals. Peter Anderson (PJA Design) provided much appreciated assistance with the computer modelling. The Tasmanian Fox Taskforce provided support during the study period. Valuable improvements to the manuscript were made by Graeme Nicholson, Alan Lill and two anonymous reviewers.


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