deer

Introduced ungulates are an important management issue on New Zealand’s public conservation land (PCL). Ungulates are harvested by recreational and commercial hunters, with some government-funded culling. A robust monitoring system is needed to reliably report trends in occupancy and abundance, and to evaluate management effectiveness. We first describe the design and implementation of a monitoring programme enabling ungulate occupancy and relative abundances to be estimated on New Zealand’s PCL.

Aerially distributed baits containing sodium fluoroacetate (1080) are used in New Zealand for small-mammal pest control over an average of about 600 000 ha each year. This can also kill non-target species, including deer. This incidental mortality of deer generates antipathy to 1080 amongst many hunters, adding to the broader opposition to aerial 1080. Hunter opposition to 1080 baiting has also prompted the development of deer-repellent 1080 bait formulations. Historical estimates of deer mortality varied widely but were sometimes high.

Sika deer (Cervus nippon) have attained high densities within their introduced range in the central North Island, New Zealand. They are an important big-game species for recreational hunters in New Zealand, but they can have unwanted impacts on native plants, such as reducing seedling growth rates. Management of sika deer requires detailed knowledge about which resources are important to them and how resource selection changes temporally.

The first deer to invade an area of forest on Secretary Island show an almost exclusive preference for bark of Pseudopanax colensoi var. ternatum. Young shoots of P. linearis and juvenile P. crassifolium are also sought. Intensive browsing is begun in areas of Asplenium bulbiferum and continued where Polystichum vestitum and bushes of Coprosma spp. are plentiful. The foregoing are the main species being killed by deer but others are being taken in increasing quantity.

Results of some control campaigns suggest that the characteristic features of response to reduction of numbers (improved physical conditions, higher reproductive rates) are suppressed when the control technique disrupts the ability of survivors to exploit preferred components of the habitat.

Introduced mammalian herbivores are changing the structure and composition of New Zealand’s forest ecosystems and may modify forest succession after natural disturbances. We studied how introduced ungulates (red deer and feral pigs) and rodents (rats and house mice) affected the rate of recovery (i.e. the engineering resilience) of the forest understorey following artificial disturbance.

The National Vegetation Survey (NVS) databank is designed to safeguard the investment of millions of dollars spent over the last 50 years collecting, computerising and checking New Zealand vegetation data and to optimise the potential knowledge gains from these data. Data such as these can be synthesised across a range of spatial and temporal scales, allow novel ecological questions to be considered, and can underpin land management and legal reporting obligations.

Feral goats (Capra hircus) were studied in the Mahoenui giant weta reserve, southern King Country, New Zealand, from March 1992 to February 1993. The reserve supports the main population of the undescribed Mahoenui giant weta (Deinacrida sp.). Gorse (Ulex europaeus) is the dominant woody browse plant in the reserve and provides protection, shelter and food for weta. The activities, foraging behaviour and diet of feral goats within the reserve were measured by direct observation and analysis of rumen contents.

The history of the New Zealand biota over the last 7000 years may be divided into three phases. BC 5000 to AD 1000 was a period of comparative ecological stasis. That equilibrium was disrupted between AD 1000 and AD 1800 by the destruction of most of the New Zealand plant-herbivore systems, the co-evolutionary relationship between the plants and the vertebrate herbivores being decoupled by about AD 1400. After AD 1800 new plant-herbivore systems were progressively developed and new ecological relationships forged.