I’ve often heard this bird at home at night and wondered what it could be. A combination of “The National Photographic Index of Australian Wildlife: Cuckoos, Kingfishers, Nightbirds of Australia” (edited by Strahan) and Michael Morecombe’s “Birds of Australia” ap (which has bird sounds) helped me track it down. It has a distinctive rising, accelerating series of notes – the white-throated nightjar (Eurostopodus mystacalis).
According to the book, it is about the size of a pigeon (although it doesn’t say which pigeon and they do vary in size – rainforest pigeons are much bigger than rock pigeons) and is rarely seen by day. It squats motionless on the ground and its colouration helps it blend in with the leaf litter:
Birds from southern Australia are migratory, wintering in New Guinea and northern Australia and returning to their original roosting and breeding territories in the spring (when moths and flying beetles [their prey] are abundant. Birds in northern Australia are sedentary [do not migrate] … Calling birds are often heard on spring nights [i.e. now] … in the drier eucalypt forests of the coast and ranges.
I’ll have to listen and observe whether the noise goes away in winter, but my initial impression is that it is present all year, so maybe my area classifies as ‘northern Australia’.
Nice to finally have solved the mystery.