Biology of the rabbit (Oryctolagus cuniculus (L.)) in Central Otago, New Zealand, with emphasis on behaviour and its relevance to poison control operations.
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
This research arose from concern over declining success rates of rabbit poisoning operations in Central Otago. It consisted of a detailed study of behaviour in a natural population of rabbits which was subsequently poisoned. The aim was to test the hypothesis that social behaviour and the existence of neophobia could be contributing to control operation failures. Several other aspects of rabbit biology in Central Otago were investigated including population age and sex structure, growth and condition, and reproduction. Information on rabbit behaviour was obtained from intensive observation of a population of 50-100 rabbits over a period of two years. Activity budget results for the period of peak emergence (late afternoon-early evening) revealed similar patterns to those recorded previously, with some minor differences in the classification of individual behaviours. Social organisation varies seasonally and spatially, with a range of social structures present at anyone time. Heterogeneity of the habitat, in particular the patchiness of the food supply, influenced spatial and temporal features of social organisation. Reproductive efficiency and optimal use of resources appear to be important determinants of social structure; the concept of economic defendability is relevant. Activity range size and shape were extremely variable with female rabbits generally having larger ranges than males. Some relationship between activity range size and metabolic requirements and economic defendability was evident. Gross movement patterns were a product of habitat heterogeneity and the limited availability of permanent resting locations because of the unsuitability of the substrate for burrowing. Age structures of rabbit populations in Central Otago are characterised by relatively few individuals greater than 24 months old; this suggests high mortality and a rapid turnover rate. Growth and condition results reflect some measure of environmental conditions in Central Otago. Seasonal variation in fat-related condition suggests hormonal control of fat reserves rather than regulation by resource availability. The breeding season is sharply defined, a product of severe and strongly seasonal environmental conditions. Annual productivity is about 22 young per female. Evidence is presented for the existence of neophobia in Central Otago rabbit populations. Despite the genetic basis for this trait, environmental factors may influence an individual's propensity to exhibit neophobia. This may account for the considerable variation in neophobic responses among individual rabbits.