Overview

Distribution

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.

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Range

Sparse in arid and semiarid areas of Australia with scattered trees.

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Ecology

Habitat

Habitat and Ecology

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
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
VU
Vulnerable

Red List Criteria
D1

Version
3.1

Year Assessed
2012

Assessor/s
BirdLife International

Reviewer/s
Taylor, J. & Butchart, S.

Contributor/s
Olsen, P. & Schoenjahn, 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.

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Population

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
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Threats

Major Threats

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).

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Management

Conservation Actions

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).

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Wikipedia

Grey Falcon

The Grey Falcon (Falco hypoleucos) is a rare medium-sized falcon, one of the enigmatic ‘mystery’ birds of Australia, neither easily nor predictably seen. Recent studies however have contributed to the gathering of further information on this elusive bird of prey.[2] One of the reasons behind this lack of information could be the difficulty in identifying a Grey Falcon while in the field. Schoenjahn (2010) has identified other species of birds which are often mistaken for a Grey Falcon such as the; Brown Falcon (Falco berigora), Grey Goshawk (Accipiter novaehollandiae), adult Collared Sparrowhawk (Accipiter cirrhocephalus), Brown Goshawks (Accipiter fasciatus) and the Black-shouldered Kite (Elanus axillaris).[3]

Description[edit]

Mainly grey upperparts and white underparts; darker on the tips of the flight feathers; yellow cere. Body length 30–45 cm; wingspan 85–95 cm; weight 350–600 g. Females larger.[4] Grey Falcons are known to have a body length between 30–45 cm, making them a mid-sized bird. Females are generally larger in body size and wingspan.[5] The wingspan of a male is less than 300mm and the tail length is less than 150mm. For the females, the wingspan is generally more than 305mm and the tail length is more than 150mm. The weight of the Grey Falcon also fluctuates with gender.[3] The female weighs approximately 559 grams on average (and between 486 and 624g) and the male is 378 grams (and between 335 and 419g).[6] The Grey Falcon has mostly grey upper body parts. It is heavy-shouldered with a black streak under the eyes. The wingtips are also black and the cere, eye ring and feet are a very vibrant yellow. The tail of the bird is grey and faintly barred like the underwings. The lower section of the body is white with fine dark streaks and on younger birds this feature is darker and more distinctive. The call of the Grey Falcon is Hoarse chattering, clucking and whining sounds. It is similar to the Peregrine Falcon and has a loud, slow ‘kek-kek-kek’ or ‘kak-ak-ak-ak’ but is slower, deeper and harsher than the Peregrine Falcon. [7] Grey falcons are also a lazy bird they mainly like to use abandoned nests and not bother to make their own.

Distribution and habitat[edit]

The Grey Falcon is an Australian endemic, usually confined to the arid inland. Open country: Triodia grassland, Acacia shrubland, and lightly timbered arid woodland.[4] They have been sighted over most of mainland Australia except for Cape York. Very few have been seen on the Nullarbor Plain and in the Great Victoria, Gibson and Great Sandy Deserts. Most sightings of the Grey Falcon have been within the arid zones, with rainfall less than 500mm. When they have been occasionally seen outside of these areas, they have been found in similar dry, low altitude, open woodland or grassland. The only times this bird has been seen in different conditions has been along the Queensland coast during drought years. The Grey Falcon is often seen in family-type groups of an adult pair and usually one (but up to four) first year birds.[8]

Conservation[edit]

It is found at very low densities, numbering only 1,000 breeding pairs, and the population may be stable. Continued high levels of grazing in arid zone rangelands and clearance of the semi-arid zone for marginal farming is degrading habitat.[4]

International[edit]

The species was previously listed as Near Threatened; in 2012 it was uplisted to Vulnerable.[9] Listed on CITES Appendix II.

Australia[edit]

Grey Falcon are listed as endangered on the Australian Environment Protection and Biodiversity Conservation Act 1999.[10]

State of Victoria, Australia[edit]

  • On the 2007 advisory list of threatened vertebrate fauna in Victoria, The Grey Falcon is listed as endangered.[13]

State of Queensland, Australia[edit]

Behaviour[edit]

Diet[edit]

When sighted and observed, most Grey Falcons have been seen hunting. They have a habit of eating on the ground, in the open and around inland bores which make them quite easy to observe while eating. From 88% of observations it can be said that their main prey is other birds, followed by small mammals (6%), reptiles (5%) and insects such as worms (1%). The birds which they feed on usually form flocks and feed on the ground which is typical of birds in arid regions such as parrots and pigeons. Grey Falcons have also been sighted with animals such as; a Mallee Ringneck, a duck, a Yellow-rumped Thornbill, locusts, snakes, a large dragon, the House Mouse, rabbit kittens, lamb carcasses and one has even been seen pursuing a bat.[8]

Nesting[edit]

The Grey Falcon’s breeding range has shrunk recently with breeding occurring in the more arid sections of their distribution.[8] They breed once a year but may nest twice a year during abundant seasons or may not nest during drought times. Breeding and nesting occur within the distribution range with nests normally being an abandoned stick nest from another species of bird of prey. Nests are often selected in an upright fork, of the top of a tall tree. These can be located in a patch or a belt of timber along a watercourse in dry inland areas. Nests can be used for several years within the nesting season of July to October in the south and April to June in the North. The Grey Falcon eggs look very similar to the Black Falcon’s (Flaco subniger) but are slightly smaller. A clutch size is generally two or three and occasionally four eggs that are oval shaped and 51x38 mm on average.[15]

References[edit]

  1. ^ BirdLife International (2012). "Falco hypoleucos". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013. 
  2. ^ Watson, C. (2011). A failed breeding attempt by the Grey Falcon ‘Falco hypoleucos’ near Alice Springs, Northern Territory. Australian Field Ornithology, 28 (4), 167-179.
  3. ^ a b Schoenjahn, J. (2010). Field identification of the Grey Falcon ‘Falco hypoleucos’. Australian Field Ornithology, 27(2), 49-58.
  4. ^ a b c Marchant, S.; & Higgins, P.J. (Eds). (1993). Handbook of Australian, New Zealand and Antarctic Birds. Vol. 2: Raptors to Lapwings. Oxford University Press: Melbourne. ISBN 0-19-553069-1
  5. ^ Marchant, S.; & Higgins, P.J. (Eds). (1993). Handbook of Australian, New Zealand and Antarctic Birds. Vol. 2: Raptors to Lapwings. Oxford University Press: Melbourne. ISBN 0-19-553069-1
  6. ^ Schoenjahn, J. (2010). Morphometric data from recent specimens and live individuals of the Grey Falcon (Falco hypoleucos). Corella, 35(1), 16-22.
  7. ^ Simpson, K & Day, N. (2004). Field guide to the birds of Australia. Penguin Books –Viking.
  8. ^ a b c Olsen, P. D. (1986). Short communications - Distribution, status, movements and breeding of the Grey Falcon Falco hypoleucos. CSIRO, 47-51.
  9. ^ "Recently recategorised species". Birdlife International (2012). Retrieved 15 June 2012. 
  10. ^ EPBC Act List of Threatened Fauna. environment.gov.au
  11. ^ Department of Sustainability and Environment, Victoria
  12. ^ Department of Sustainability and Environment, Victoria
  13. ^ Victorian Department of Sustainability and Environment (2007). Advisory List of Threatened Vertebrate Fauna in Victoria – 2007. East Melbourne, Victoria: Department of Sustainability and Environment. p. 15. ISBN 978-1-74208-039-0. 
  14. ^ Queensland Department of Environment and Resource Management
  15. ^ Beruldsen, G. (2003). Australian birds, their nests and eggs. G. Beruldsen.
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