The ventral surface of the wings has a rufous-brown lining, a dark carpal crescent, and a boldly barred finger.

Square-tailed kites also have a black bill, with a pink base and cere, and short legs and feet which are whitish or cream.

Juveniles are easily distinguished from adults by the lack of the white face and their richer rufous colouration (on both the head and the body).

[3] The square-tailed kite is a specialised canopy-dwelling predator, and can be found in a number of different habitats including open and temperate forests, woodlands, scrub, heathland, riverine trees, and savannah.

[6] Land clearing is a particularly significant threat, with the removal of trees that could be used by the birds for nesting and breeding causing dispersal and competition for the resources that are still available.

The species will benefit from any environmental protections in place across its range that preserve suitable square-tailed kite habitat, as well as revegetation of open or urban areas.

[3] Square-tailed kites hunt for food by soaring slowly above or through the tree canopy, skimming over grass, flying transect lines, or quartering.

[3] The diet of square-tailed kites includes avian prey-both smaller birds and eggs, small mammals such as mice, insects, molluscs (snails), and reptiles.

[2][7] Avian prey is typically young birds such as nestlings or juveniles, and square-tailed kites have been observed preying upon a range of other bird species including crested pigeons (Ocyphaps lophotes), New Holland honeyeater (Phylidonyris novaehollandiae); eastern yellow robin (Eopsaltria australis), rufous whistler (Pachycephala rufiventris)[7] and juvenile Pacific koel (Eudynamis orientalis).

The male pursues the female, and the pair perform aerial rolls in which the talons are presented but do not make contact.

[7] Threat displays for this species include 'staring' at other birds with the bill open, and the feathers of the head and neck upright.