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Falco hypoleucos

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA AVES FALCONIFORMES FALCONIDAE

Scientific Name: Falco hypoleucos
Species Authority: Gould, 1841
Common Name(s):
English Grey Falcon
Spanish Halcón Gris, Halcón Gris de Australia

Assessment Information [top]

Red List Category & Criteria: Vulnerable D1 ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Taylor, J. & Butchart, S.
Contributor(s): Olsen, P. & Schoenjahn, J.
Facilitator/Compiler(s): Garnett, S., McClellan, R., O'Brien, A., Symes, A., Taylor, J.
Justification:
This species has been uplisted to Vulnerable because although it has an extremely large range, and historical populations declines and range contractions are believed to have ceased, it occurs at very low densities and its population has been precautionarily estimated to number fewer than 1,000 mature individuals. If the population size is eventually found to be larger than currently feared it may be eligible for downlisting.

Geographic Range [top]

Range Description:

Falco hypoleucos is infrequently seen over much of arid and semi-arid Australia. Its range covers eastern Australia, especially arid regions, and northern Australia south to approximately 26oS, south of which it is casual in occurrence (Johnstone and Storr 1998). It may have been eliminated from some breeding areas early in the 20th century, particularly those with more than 500 mm annual rainfall in New South Wales, where its eastern limit has also shifted further inland since the 1950s (Olsen 1998). The contraction in its breeding distribution (Garnett 1993) is attributed to habitat degradation, which reduced the suitability of some semi-arid habitat and restricted the species to the arid zone (Olsen 1998). The main breeding distribution now covers areas where annual rainfall is <500 mm (Garnett et al. 2011). The present range is believed to be stable, and it is apparently more widespread during inland droughts. There is evidence of regular seasonal movements between the arid zone and northern Australia, and possibly New Guinea, and from west to east in Queensland. It is always found at very low densities, and its population is believed to number only 1,000 mature individuals in total (Schoenjahn 2011, Garnett et al. 2011). These estimates are based on limited information about the species and comparison with data for the Peregrine Falcon Falco peregrinus (J. Schoenjahn in litt. 2007). The population of F. hypoleucos is thought to be stable.

Countries:
Native:
Australia
Vagrant:
Papua New Guinea
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population:

The species always occurs at low densities and other grey raptors are often misreported as Grey Falcons; the AOO is nominally estimated at 0.1% of the EOO as the species has been encountered very infre­quently during extensive dedicated searching in many parts of arid Australia over the last decade (Schoenjahn 2011). By comparing the range and number of sightings per 1 degree block in the first Atlas (Blakers et al. 1984), it is estimated that the Grey Falcon occupies about 0.27× the area occupied by the Peregrine Falcon F. peregrinus (99 compared to 365 grid blocks) at an average of one-quarter its density. Given an estimated 3,000–5,000 pairs of Peregrines in Australia (Olsen and Olsen 1988, in Garnett et al. 2011), this suggests a total of 200 to 350 pairs of Grey Falcon (Schoe­njahn 2011). The second Atlas (Barrett et al. 2003) reports sightings in 118 (14%) compared with 384 (47%) of grid blocks, for the Grey Falcon and Peregrine Falcon respec­tively. At one-third the distribution and a little over half the density, the estimated population is 550–915 pairs. The average of the mid-point of these ranges, about 500 pairs, is considered appropriately precautionary, espe­cially considering the uncertainty and historical declines (Garnett et al. 2011), thus the population is estimated here at 999 mature individuals.

Population Trend: Stable

Habitat and Ecology [top]

Habitat and Ecology:

The distribution of this species is centred on inland drainage systems where there is an average annual rainfall of less than 500 mm. It favours timbered lowland plains, particularly acacia shrublands that are crossed by tree-lined watercourses, but frequents other grassland and woodland habitats. It hunts birds (mostly parrots and pigeons), insects (Johnstone and Storr 1998), and mammals, and will also feed on carrion. It uses the abandoned nests of other bird species, particularly raptors, or corvids (Johnstone and Storr 1998), and lays one to four eggs in July or August (Johnstone and Storr 1998). Its preferred nests are usually in the tallest trees along watercourses. In any particular area nesting may only take place in years of above average rainfall, with birds leaving in drier years.

Systems: Terrestrial; Freshwater

Threats [top]

Major Threat(s):

The 20th century decline and range contraction was caused by overgrazing in arid zone rangelands and clearance of open woodland in the semi-arid zone for marginal farming, which degraded habitat and affected prey abundance and nest site availability (Garnett 1993). Localised DDT-related eggshell thinning of up to 15% was detected when this pesticide was legal, but is no longer considered a problem. Nest-site availability, particularly in sparsely-treed inland areas, may eventually become a limiting factor, especially where grazing by introduced herbivores is preventing tree regeneration. All threats are speculative and are largely at the wetter margins of the species's range where it might be out-competed by the more mesic Peregrine Falcon F. peregrinus. The species's eggs are sought after by egg-collectors, and eggs and young may be taken for falconry (Garnett 1993).

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
CITES Appendix II. Research on the species was underway in 2007 (J. Schoenjahn in litt. 2007).

Conservation Actions Proposed
Develop methods for assessing population trends. Survey and record regeneration status of nesting habitat. Carry out regular monitoring of the species in selected parts of range, including both arid and semi-arid zones. Study its biology, ecology, and conservation status and needs (Garnett 1993, Olsen 1998). Document nest-sites and encourage protection by volunteers (Garnett 1993).


Citation: BirdLife International 2012. Falco hypoleucos. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 30 September 2014.
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