Black falcon

When attempting to identify a flying raptor Debus & Davies[3] recommend concentrating on the bird's silhouette (including shape of wings and proportions), flight style and vocalisations, rather than on details of colouration.

Australian falcons can be differentiated from hawks by their toothed upper mandible (with a corresponding notch in their lower mandible) and by their long pointed wings.[3]

Brown falcons (Falco berigora) are a common and widespread species in Australia, and they are the most likely to be confused with the black falcon (particularly brown falcon juveniles and black morphs).[4] In fact, Debus & Olsen[2] suggest many observations and behaviour of brown falcons have mistakenly been attributed to the black falcon, due to incorrect identification. The two species differ in the relative length of exposed tarsi (the lower, visible half of the bird's leg) compared with thigh feathers, flight style, wing attitude, and bold underwing barring and tail barring (which appear on the brown falcon only).[5][6][7]

Black falcon in flight

The falcon's flight has been described as variable. Generally it flies with relaxed ‘crow-like’ wingbeats with occasional soaring. It also flies with a stiffer, shorter wingbeat. It glides and soars with slightly drooped or sometimes horizontal wings, carpals forward (wings are stretched out straight when gliding). Tail is normally folded (except when soaring, when it is fanned with notched corners). It often soars for long periods without flapping and catches prey in the air or on the ground. In pursuit of prey it uses powerful, rapid wingbeats. While resting the bird's wing tips are shorter than the tail and legs appear short.[3][4]

The species usually hunts alone but has also been observed hunting cooperatively in pairs and occasionally in larger numbers, when prey is abundant (specifically, when stubble fires yield an abundant prey source.[6] Twelve birds were seen at one such fire near Gundagai, NSW.[6]

They have often been observed using contour hunting (over treetops), surprising and taking birds on the wing. They will sometimes tail chase other birds over long distances, and less often engage in a Peregrine-like vertical stoop when hunting.[12] The species preys upon and is sometimes the prey of other raptors.[13]

The black falcon's diet primarily consists of bird species, from finch to cockatoo size but they have also been observed feeding on small mammals (i.e. rabbits, mice and rats), insects and carrion.[2][6] Avian prey species include:

• various pigeons (including crested pigeon Ocyphaps lophotes and the feral rock dove Columba livia)
• Australian pipit (Anthus australis)
• Australian magpie (Gymnorhina tibicen)
• Australian ringneck (Barnardius zonarius)
• Black-faced Cuckooshrike (Coracina novaehollandiae)
• Blue bonnet (Northiella haematogaster)
• Budgerigar (Melopsittacus undulatus)
• Common starling (Sturnus vulgaris)
• Eastern rosella (Platycercus eximius)
• Fairy martin (Petrochelidon ariel)
• Galah (Eolophus roseicapillus)
• Grey Teal (Anas gracilis)
• Honeyeaters (Meliphagidae)
• Horsfield's bush lark (Mirafra javanica)
• Little buttonquail (Turnix velox)
• Little corella (Cacatua sanguinea)
• Musk lorikeet (Glossopsitta concinna)
• Stubble quail (Coturnix pectoralis)
• Zebra finch (Taeniopygia guttata)

Debus & Zuccon also observed the black falcon hunting turquoise parrot (Neophema pulchella) and apostlebird (Struthidea cinerea), but on these occasions the attacks were unsuccessful.[6]

Laying time: between May and November (usually July to September). Clutch size: 1 - 5 (usually 3 or 4). Egg size: 42x32 mm. Incubation: approximately 34 days (by female, possibly by male for short periods). Nestling period: 5.5 – 7 weeks. Life span: at least 12 years in the wild, and 20 years in captivity. [3][4][6]

The black falcon nests in living or dead trees, using the stick nests of corvids or other raptors.[3] It may take over nests occupied by other birds.[4] It appears there may be interspecific competition for nest sites between the black falcon and other raptors and corvids.[14] Nest sites may be a limiting factor for black falcons, specifically where there has large-scale vegetation clearing, such as occurred in the sheep-wheat belt of NSW.[2]

During breeding season males perform courtship displays such as horizontal figure eights around the nest.[3] The male bring food to the female during incubation and brooding. During the later nestling period both sexes may forage to feed the young.[5][14]

Post-fledging behaviour and development of young falcons appears to be very similar to that of the peregrine falcon, and includes spending time with siblings and parents, and practicing hunting, territorial and courtship behaviours.[15]

The most common call is similar to the 'cackle' of the peregrine falcon but is slower and deeper – gaak-gaar-gaak. The guttural call is shorter and more rapid when being attacked or when intruders are nearby – gak-gak-gak-gak.[4][6] Some authors suggest the bird screams when attacking prey but this attribution could be a result of misidentifications of brown falcons, with other authors contesting that the birds are generally silent during attack.[2] The male also makes a sharp, rather high-pitched eeik..eeik..eeik or ee-chip…ee-chip during courtship displays, and the female has a whine or wail when begging for food or copulating.[6]

The species’ home range is undetermined, but likely to be greater than 100 km².[9] The species appears to be wide-ranging in the non-breeding season, but is also known to stay in regular non-breeding territories for lengthy periods.[2]