Black-Shouldered Kites are around 35 to 38 cm in length and have a wingspan of between 80 and 95 cm. Adults are a very pale grey with a white head and white underparts. The leading edge of the inner wing is black. When perched, this gives them their prominent black "shoulders".
Although reported from almost all parts of Australia, they are most common in the relatively fertile south-east and south-west corners of the mainland, and in south-east Queensland. They are rare in the deep desert and appear to be only accidental visitors to northern Tasmania and the Torres Strait[?] islands. Although found in timbered country, they are mainly birds of the grasslands. European occupation of Australia has, on the whole, benefited them by clearing vast expanses of forest for agriculture and providing suitable conditions for much larger numbers of mice.
Black-shouldered Kites live almost exclusively on mice. They take other suitably-sized creatures when available, including grasshoppers, rats, small reptiles, birds, and even (very rarely) rabbits, but mice and other mouse-sized mammals account for over 90% of their diet. Their influence on mouse populations is probably significant: adults take two or three mice a day each if they can, and on one occassion a male was once observed bringing no less than 14 mice to a nest of well-advanced fledglings within an hour.
Like other elanid kites, Black-shouldered Kites hunt by quartering grasslands for small creatures. This can be from a perch (usually a dead tree, as illustrated above), but more often by hovering in mid-air with conspicuous skill and little apparent effort. Typically, a kite will hover 10 to 30 metres above a particular spot, peering down intently, sometimes for only a few seconds, often for a minute or more, then glide swiftly to a new vantage point and hover again.
When a mouse is spotted, the kite drops silently onto it, feet-first with wings raised high; sometimes in one long drop to ground level, more often in two or more stages, with hovering pauses at intermediate heights. About two-thirds of attacks are successful. Prey can be eaten in flight or carried back to a perch.