[2] The Australian hobby has been recorded preying on avian species including the European starling (Sturnus vulgaris), house sparrow (Passer domesticus), crimson rosella (Platycercus elegans) and silvereye (Zosterops lateralis).

Research suggests they tend to avoid large, dangerous, or agile species that forage close to cover, such as the common myna (Acridotheres tristis).

[5] Insectivorous bats[2][10] and insects including beetles, cicadas, crickets and grasshoppers also form part of the hobby's diet.

[11] The hobby is a solitary and aggressive falcon using rapid flickering wing beats, with tail fanned when hovering.

[2] When engaged in territorial defence, hobbies have been observed soaring and circling to ward off other birds of prey e.g. little eagle (Hieraaetus morphnoides).

[2] Hobbies have been witnessed catching their prey in mid air, by direct attack from a perch or in fast contour-flying above or between tree canopies.

[2] Research has shown that Australian hobbies have one of the lowest prey-to-predator ratios (i.e., smaller prey relative to their body mass) because of the large number of insects in their diet.

Early on in the nestling period the male hunting rate increases to supplement the female, with observations indicating food is brought to the nest every three hours, with a longer break in the middle of the day.

[12] Research undertaken comparing the vocalisations of Australian falcons, found that two structurally distinct calls were emitted when a male hobby was restrained.

Juveniles were observed calling in an unslurred chittering whine when begging for food and in a chattering kee-kee-kee... when alarmed, or excited, from the feathering stage.

[12] Calls by the Australian hobby are similar, but higher pitched, to the male peregrine falcon (Falco peregrinus) when arriving at the nest with food.

[16] After DDT was introduced to agriculture in 1946, egg shell thickness of some species of falcon, including the Australian hobby, was significantly reduced.