SPECIES

Black Falcon Falco subniger Scientific name definitions

Stephen Debus
Version: 2.0 — Published March 17, 2023

Movements and Migration

Movement

Collated evidence is mainly observational, supplemented by a few band recoveries. The movements of Black Falcon are poorly understood, but there are believed to be resident, dispersive, migratory, and nomadic or irruptive segments of the population according to rainfall and food supply, e.g., irruptions of prey (locusts, rodents, quails Coturnix and Synoicus spp., button-quails Turnix spp.) in the arid and semi-arid zones (1). At a continental scale, there is a seasonal shift in reporting rates northwards in autumn–winter (March to August) and southwards in spring–summer (September to February) (36). At least some breeding pairs appear to be resident in the eastern agricultural zone (10, 19), although there may be some temporary, local post-breeding dispersal by females (7, 38). Individuals, possibly juveniles and subadults, are post-breeding (mostly late spring to early autumn, November–March/April) visitors to grasslands and open woodlands at high elevations (>1000 m) in the temperate southeastern tablelands, where the species does not breed (5; SJSD). During good seasons and abundant prey, there is a post-breeding (summer–autumn) influx of adult and juvenile falcons into the South Australian agricultural zone (39, 17) which has a Mediterranean-type climate of cold wet winters and hot dry summers. Black Falcon is an irruptive breeder in the arid zone in wet years, though absent in very dry years (1, 3), and in the dry season (austral winter, June–August) it migrates to tropical coastal floodplains to breed (33, 40). There is also some coastward dispersal and breeding near the eastern coast during inland droughts (1, 3). It is said to be a rare visitor (casual or drought refugee), mainly in autumn and winter, to the arid and semi-arid zones of Western Australia (41), although there are also breeding records for the northern arid zone (36, 32).

The few banding recoveries of Black Falcons, all banded in southeastern Australia and mostly in a post-breeding dispersal area, involved two birds retrapped at the banding site 3–6 years later and one recovered 14 km away, all in the post-breeding period. Those three were of unknown age (first year or older) and sex, banded in autumn. A fourth, recovered in the same post-breeding area, had been banded as a nestling 346 km away, 12 years earlier (5).

Dispersal and Site Fidelity

Natal Philopatry and Dispersal

Almost no information. A Black Falcon banded as a nestling was recovered 346 km away in a post-breeding dispersal area and period 12 years later (5), but its whereabouts or movements in the interim are unknown.

Adult Fidelity to Breeding Site and Dispersal

Based on individual behavior and morphology, e.g., plumage characters, individual variation, and their changes in monitored pairs, adult breeding Black Falcons in some temperate areas are resident in the same breeding territories for several consecutive years (10, 19). However, it is not known if or how many of these birds remain, disperse, or migrate after the breeding season. Some adult females in the temperate zone may leave the vicinity of the breeding territory after a breeding failure or after disappearance of dependent juveniles, while the male parent remains (7, 38). Some pairs in the temperate zone may occupy temporary (summer) nonbreeding territories (5).

Migration Overview

Information needed.

Timing and Routes of Migration

Information needed. General north–south seasonal movements are inferred (36).

Migratory Behavior

No specific information. Black Falcon is capable of soaring high on thermals for long periods and making long commuting glides of > 2 km at height (42, 21, 1, 17, 43, 44; SJSD); it travels effortlessly (22).

Control and Physiology of Migration

Information needed.

Recommended Citation

Debus, S. (2023). Black Falcon (Falco subniger), version 2.0. In Birds of the World (S. M. Billerman, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.blafal1.02