Abstract :
Hatchlings of the Australian brush-turkey, Alectura lathami, should respond to predators innately because they hatch independently of nest-mates, have no contact with parents, and initially live solitarily. Their response to predators was tested in a large outdoor aviary set in natural rainforest habitat. Two living predators, a cat and a dog, as well as a moving rubber snake and raptor silhouette were presented to observe whether different predators evoked different innate responses. Controls consisted of cardboard boxes of equal coloration, shape and dimensions. Ten chicks were tested per stimulus type, and their response measured as latency to the first step and proportion of time spent performing different behaviours, during presentation of the stimuli and thereafter. While the snake evoked mainly running and this was obvious only during the test, the three other stimuli also led to a difference in behaviour after presentation. The raptor and cat evoked more crouching than other stimuli and the dog more running. Latency to the first step was higher in the raptor tests than during others. However, there was no difference in response between the stimuli and controls, suggesting that the releasing mechanism for evoking a response is likely to be size, dimensions, height and/or relative speed. Hatchlings were also presented with an acoustical stimulus, alarm calls of songbirds; its control was white noise. They responded to this by being more vigilant than in other tests, and, as with the snake, this response was only obvious during the test. In contrast to the optical stimuli, chicks did not respond to the control for the acoustical stimulus, indicating that megapode chicks, which have no parents to warn them, possess an innate response to alarm calls of songbirds instead. The results of this study also suggest that a lack of predator recognition should be of little concern in the translocation of endangered megapode species, even when chicks have to deal with introduced predators, and that other factors such as the availability of cover should be given greater attention.
