Comparing the anti-predator behaviour of Australian arid-zone birds with a model species, the zebra finch

Submission note: A thesis submitted in total fulfilment of the requirements for the degree of Doctor of Philosophy to the Department of Ecology, Environment and Evolution, School of Life Sciences, College of Science, Health and Engineering, La Trobe University, Victoria, Australia.

Thesis with publications.

Alarm calls are vocalisations used to warn nearby conspecifics to the presence of a threat. Flee alarm calls encourage escape, whereas mobbing alarm calls recruit individuals to harass the predator. Alarm calling is a common anti-predator behaviour exhibited by a variety of taxa. The zebra finch (Taeniopygia guttata), a native Australian passerine and a model species, is an interesting case as, while much is known about their vocal repertoire, there is very little information about alarm calling in this species. I began my research by conducting a meta-analysis of alarm calling in Australian arid-zone birds and discovered that possessing a distinct alarm call to communicate to offspring but not to adult conspecifics is rare. Predictor variables indicated that zebra finches would be expected to possess an alarm call for warning flock-mates. I then conducted field work, in which I presented zebra finches and other arid-zone birds with a gliding model of a raptor and analysed their responses. The zebra finches reacted with flight, however, unlike other species tested, they did not emit an acoustically distinct alarm call in response to the glider. Following this finding, I undertook an experiment using captive-bred birds where I exposed groups of finches to an animated looming predator. The birds responded with escape behaviour but did not emit a distinct alarm call or alter their individually stereotyped distance call post-stimulus. The rate of calling also did not change. Finally, I used a playback experiment to analyse eavesdropping in captive zebra finches. It was found that playback of the heterospecific alarm calls did not cause a change in the calling or scanning behaviour of the finches. Thus, it is still unclear if and how this species uses vocal signals to communicate alarm, and I suggest further work concentrates on alarm calling in the presence of offspring, and communication among flocks.