Integrated analysis of the movement and ecology of wild dingoes in the arid zone

Abstract

The behaviour and use of space by mammalian predators influences the structure and function of ecosystems. Mammalian predators are often highly mobile, and in resource limited environments they need to move through spatially distinct habitats in search of prey, water, refuge, and conspecifics. This increases connectivity between ecosystems and can have important ecological implications for food web stability. Underlying a predator’s decision to move is the need to balance requirements for energy acquisition and expenditure. Advances in remote monitoring technology are increasing our ability to gain detailed, quantitative insights into the movement ecology and ecophysiology of wild animals. However, methodological and analytical complexities have impeded the integration of different biologging tools. In this thesis I explored the biology of Australia’s largest terrestrial predator, the dingo Canis dingo, and adopted an integrative approach to studying the ecology of wild individuals. My research focused on the genetics, behaviour, resource selection, and energetics of a population of dingoes in remote central Australia. The population exhibited high genetic purity (mean purity > 90%) and clear phenotypic variation in coat colour. Genetic analysis of 83 individuals revealed high levels of relatedness, and both promiscuous and monogamous mating strategies. Morphological analysis of prey remains in dingo scats collected from our study site showed European rabbits Oryctolagus cuniculus dominated their diet, which was mirrored in a meta-analysis of the diet of dingoes across the 5.4 million km2 arid zone. Whenever food availability boomed during resource pulses, hyperabundant small and medium sized mammals became their primary prey. Dingoes showed considerable dietary similarities throughout the arid zone, despite some sites being separated by a distance equivalent to that between Spain and Russia. Using captive dingoes fitted with accelerometers, we developed a classification model that predicted 14 behaviours from accelerometry data collected at the very low frequency of 1 Hz. The high accuracy (mean = 87%) of these predictions, even at a low sampling frequency, suggests that reliable, fine-scale behavioural observations of wild animals can be made over a longer period than was previously thought possible. To investigate resource use at both the individual and population level, we obtained > 150,000 GPS locations from 18 dingoes over a two year period. At the population level, dingoes selected strongly for watercourses and avoided salt lakes, which is not surprising considering the survival of canids in desert ecosystems is contingent upon access to free water and refuges. Interestingly, there was extreme individual variation in space use by dingoes, as well as seasonal differences in activity patterns where females shifted their behaviour from crepuscular to diurnal during the pup whelping and rearing seasons. We recorded accelerometry data from seven wild dingoes, and were able to apply our classification model to predict fine time-scale behaviours. We then used these behaviours to create activity-specific time-energy budgets by incorporating energetic data previously reported in the literature. This is one of the first attempts at integrating location, accelerometry, and energetic data, and allowed the comprehensive assessment of the daily costs of living in a wild canid. Our results revealed that ambient temperature (Ta) drives the activity and energetics of dingoes in the arid zone, with substantially lower activity when external temperatures were high, equating to lower daily energy expenditure in summer than in winter. Moreover, the negative relationship between dingo activity and Ta during the day implies that high heat gain from solar radiation is a factor that limits diurnal activity in an arid environment.