Bait consumption and biology of tammar wallabies in the Rotorua region

The research findings outlined in this report provide information on aspects of bait acceptance by, and the biology of, the tammar wallaby (Macropus eugenic Desmarest) in the Rotorua district of North Island, New Zealand. Emphasis has been given to information that is relevant to the cost effective control of this species by methods of poison baiting, shooting and trapping and to a suitable method of monitoring population levels. Success in poison baiting is influenced by two sets of factors. Firstly, those which influence the likelihood of an animal encountering and commencing to eat a bait; secondly, those which increase the likelihood of ingestion of a lethal dose during a feeding event or a meal. The first strategy has to do with manipulation of bait density (the number of baits per square kilometre), bait siting (preferential location of baits in the target species' known feeding area or travelling routes), and with inducing the target species to sample or to resample the bait (maximising its 'acceptance'). An appropriate and cost effective choice in respect of this strategy can only be made with a detailed knowledge of 1) the distribution of the target species within the terrain that it inhabits; 2) the particular locations at which the animal is liable to feed; 3) the relative acceptance and zone of influence of a bait, i.e. the distance that an animal may be attracted to a bait; 4) the likelihood of resource acquisition, i.e prevention of access of other individuals to a bait by a dominant animal, and methods by which this may be minimised; 5) the animal's reaction to disturbance by baiting and other control operations. With the exception of 3) above, these aspects are covered in the general biology section of this report. The second strategy has to do with inducing an animal that has commenced eating a bait to continue eating until a lethal dose of poison has been consumed, i.e. enhancing bait 'palatability' by increasing positive and decreasing negative reinforcement (Le Magnen 1992) experienced during the feeding event. These aspects and those of 3) above are covered in the bait consumption section of this report.