New Zealand Wakatipu white-tailed deer (Odocoileus virginianus): past and future management : A thesis submitted in partial fulfilment of the requirements for the Degree of Doctorate of Philosophy at Lincoln University

Abstract

I attempt to highlight the large gap in knowledge required to pursue New Zealand’s new approach to deer management. This approach requires identifying a complex array of species and site specific factors that potentially influence population success, impacts, value, and management for one of New Zealand’s smallest deer herds, the Wakatipu white-tailed deer (Odocoileus virginianus). White-tailed deer in North America (and in introduced populations around the world) have been researched extensively, providing an unparalleled base of knowledge to review factors that may affect Wakatipu white-tailed deer population dynamics, including habitat quality, disease, hunter harvest and interspecies competition. An overlapping spatial mosaic of limiting factors that may influence white-tailed deer population success across the Wakatipu range were identified. Further research to determine the impact these factors have on the Wakatipu white-tailed deer population, individually and collectively across the landscape, is requried to support this herd’s management. Understanding how deer populations utilise local habitat is a critical first step in designing deer management plans. I used GPS telemetry technology to identify habitat use of Wakatipu white-tailed deer. Initial disturbance to deer behaviour is commonly observed following capture and handling for collar placement. We compared the behaviour of ten deer; four resident and six translocated into a novel, geographically disjunct area, over 50 days following helicopter capture and GPS collar placement. I identified the point at which behaviour disturbed by the capture deer returned to a stable nature. Habitat use by collared deer was patchy across the landscape and did not vary between resident and translocated groups. These results suggest the probability of habitat use could be mapped to predict the presence/absence of Wakatipu white-tailed deer across the wider landscape, thus informing those areas where management and monitoring of Wakatipu white-tailed deer and their impacts on the environment should be focused. A factor limiting population success unique to New Zealand was identified. Intensive ground-based searches for white-tailed deer carcasses were conducted in the Dart Valley/Routeburn catchments following the aerial application of 1080 (sodium fluoroacetate) containing cereal baits as part of a predator control program. Frequent predator control operations will likely affect the sustainable hunting of Wakatipu white-tailed deer and growth in their population. The efficacy of two deer repellents for repelling captive white-tailed deer from consumption of nontoxic cereal baits was assessed. Both repellents significantly decreased bait consumption and I observed clear displays of aversion to repellent baits by captive deer. Ten GPS collared wild white-tailed deer were then monitored following a predator control operation using one of the deer repellents; EDR. One collared deer was poisoned following the operation confirming that EDR is not 100% effective. To support management for hunting, the most effective available deer repellent should be used in future predator control operations over the Wakatipu white-tailed deer range. Deer management plan development requires an in-depth understanding of governing legislation, population management tools and monitoring techniques. I outlined the status of these pertaining to deer management in New Zealand and identify a range of opportunities and challenges within each for developing a management plan for the Wakatipu white-tailed deer herd. Many of these are related to policy development and strategic planning, funding, and implementation processes. Also, monitoring of the Wakatipu white-tailed deer population and its environment needs to be developed from scratch. Overall, I highlight the significant research required to pursue New Zealand’s new approach to deer management. A question remains, who undertakes this work and who pays for it?