Southern boobook smallest owl on the Australian mainland, the southern boobook is long. The nominate subspecies is the largest. It has short, rounded wings and a short tail, with a compact silhouette in flight. Southern boobooks on the Australian mainland follow Bergmann's rule, in that birds from cooler and more southerly parts of the range tend to be larger. Thus, birds from the Canberra region weigh around while those from the Cape York Peninsula and Broome are around . Females tend to be a little larger and heavier than males, with males weighing and females . The southern boobook has generally dark
Southern boobook sites. Caves or ledges are alternative roosting sites if no suitable trees are available. Although unobtrusive, it may give itself away by droppings or pellets on the ground beneath. The southern boobook is mobbed by passerines if discovered. It may allow people to approach to within . The maximum age recorded from banding has been 15 years 11 months, in a bird caught and later caught again on Black Mountain in the Australian Capital Territory. Across Australia, breeding takes place from July to February, though peaks in October, and is generally earlier in more northern areas. Eggs are laid from