Australian hobby

The hobby is a solitary and aggressive falcon using rapid flickering wing beats, with tail fanned when hovering.[6] It glides on flat or slightly drooped wings with carpals flexed and outerwings swept back. Its flight is often characterised as low and fast, zig-zagging over or between vegetation and open ground.[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). Hobbies have also been observed attacking other perched raptors with steep stoops at vegetation and shallow stoops from behind for airborne raptors.[12]

The hobby is a widespread and common hunter that often hunts at dusk,[13] diurnally and sometimes nocturnally by artificial light.[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.[5] It is acrobatic in the pursuit of prey and attacks fleeing birds in a series of short shallow stoops. They have also been recorded using a concealed approach when attacking shorebird roosts, flying towards them behind the cover of dunes, cliffs or trees.[14] Hobbies have been known to harass larger birds but are not capable of killing them.[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.[11]

Nesting usually occurs any time between August and January where an old stick nest of another large raptor is commandeered.[6] Three to four heavily blotched eggs are laid with incubation taking about 35 days. Successful broods usually comprise two to three young. The fledglings remain dependent for up to three months after which the young disperse or migrate widely.[2] Studies have revealed the extent of the falcon's migration. In one case, a banded fledgling left its natal territory in Canberra, Australian Capital Territory, and was recovered 29 days later in Brisbane, Queensland, approximately 1000 km away.[8] Within their nesting territory, hobbies have been recorded using several different perches for activities including, the transfer of food between male and female, for feeding independently and for guarding the nest. Research has shown that brooding is shared by both male and female hobbies. However, feeding of the nestlings after hatching becomes the responsibility of the female. 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. This included a wide band harmonic vocalisation and a trill-type vocalisation. The trill-type vocalisation was given sporadically upon initial handling and harmonic vocalisation was assessed as the most common call of the species being used in situations of territorial defence and mobbing.[15] Observations of hobbies during breeding identified that two main calls were used by adults. One was a rapid peevish chatter Kee-Kee-Kee-Kee-Kee which was given by the male as he brought prey to the nest area and was given by both sexes in alarm, when mobbing other predatory birds and when selecting and defending the nest. The second call resembled a squeaky chittering and ticking which appears to be used in a social dominance and food possession or food begging context. 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. The hobby is also described as having similar alarm and contact calls to the Nankeen kestrel (Falco cenchroides).[15]