Evaluation of bait stations and management options for control of dama wallabies (Macropus eugenii), in the Bay of Plenty, New Zealand

Abstract

OBJECTIVES: (1) Review information on the colonisation, impacts and past management of dama wallabies in the Bay of Plenty. (2) Identify an effective bait station for delivering cereal bait to dama wallabies. (3) Identify any physical or behavioural characteristics of dama wallabies that may influence the efficacy of using bait stations as a control technique.

METHODS: This report is based on: (1) A review of the colonisation, impacts, past management practices, and possible options for the control of dama wallabies. (2) Time-lapse video equipment was used to observe captive wallabies at Rainbow Springs as they feed from three makes of bait station. (3) Rhodamine dyed non-toxic bait was placed in bait stations at the Okataina Scenic Reserve and Paehinahina Peninsula, Lake Rotoiti. Time-lapse video and faecal pellet searches were used to assess the feeding activity of feral wallabies and possums.

RESULTS AND RECOMMENDATIONS: • Dama wallabies are continuing to spread within the Bay of Plenty. To prevent further expansion of their feral range, management action must be targeted at sites of highest priority, based on rate of spread, or their proximity to sites of high conservation value, on lands of all tenure.

• Past aerial poisoning operations have achieved very high kills on wallabies, but to allow highly palatable plant species to recover, wallaby numbers will need to be kept at very low levels for a sustained period. The success of control should be judged on vegetation response therefore vegetation monitoring must also continue.

• To make best use of pest control resources, management action on wallabies should be coordinated with the control of other pests and the impacts of control on other wildlife should be monitored

• To ensure control is efficient and sustainable, toxins, baits, and a variety of control options including bait stations need to be tested on wallabies.

• A public awareness campaign on the impacts and dispersal of wallabies should to be initiated, and public concerns about methods of control need to be addressed.

• Captive wallabies were initially reluctant to feed from the "Philproof bait feeder". Of the three stations tested, the Marley downpipe "hockey stick" station was the most preferred by wallabies.

• Bait stations should be mounted with the entrance no higher than 400 mm above the ground, as this provides easy access to bait for all age classes of wallaby.

• During observed interactions between wallabies and possums, wallabies were displaced from the bait station. At Paehinahina possum densities are low (8.5 possums/100 trap nights), there was very little overlap in feeding times and only 4 interactions between wallabies and possums were observed. At Okataina where possum densities are high (c.50 possums /100 trap nights), there was no evidence that wallabies were feeding from the bait stations, though I was unable to confirm that possums were preventing wallabies from accessing bait.

• A well designed management experiments using toxic bait in bait stations, would be the most practical way to further investigate the efficacy and efficiency of bait stations for the control of wallabies. Suitable techniques for monitoring both wallabies and possums are needed. Bait containing a marker dye and time-lapse video are useful techniques for monitoring bait station use.