Data Zone
Justification of Red List category
This species has a small population comprising no more than 900-1,400 mature individuals. Ongoing habitat loss and degradation has caused substantial contractions in the species' range (it is now probably extinct in New South Wales and south-east Queensland) attributed to agriculture and forestry and an ongoing decline in mature individuals is inferred. For these reasons it is assessed as Endangered.
Population justification
This species' extreme scarcity and low density make its population size difficult to determine, reflected in a range of population estimates (using different methodologies) over the past 30 years; all, however, have suggested there are many fewer than 2,500 mature individuals. The most recent estimate, made in 2012 (DERM 2012) suggested that the population size was 700 pairs, including 100 pairs on the Tiwi islands. This was derived from data on recorded distances between breeding pairs’ nests that suggested a density of one breeding pair per 10 km of creek or river in core areas, and half that density elsewhere. These figures are higher than those used by Aumann and Baker-Gabb (1991), who suspected densities less than half those adopted by DERM (2012), and a global population size of c.350 pairs (700 mature individuals). The population size adopted here follows MacColl et al. (2021), who estimated using these previous density estimates and more contemporary data on distribution that there are between 900 and 1,400 mature individuals.
Trend justification
There is some regional variation, but overall the population is inferred to be experiencing an ongoing decline, although the rate of this remains unquantified. The 10–30 pairs estimated in the South Eastern Queensland bioregion in 2012 (see DERM 2012) appear no longer to be present (Seaton 2014), apparently going extinct sometime before 2010, while the species gradually declined to extinction in New South Wales over the 1980s and 1990s (Cooper et al. 2014). On the Tiwi Islands, nest success monitored annually has not changed significantly since 2001 (2001–2010: 50 nests, 0.56 ± 0.35 (0–1.33) fledglings/nest; 2011–2019: 100 nests, 0.69 ± 0.40 (0.4–1.6); S. Ryan unpublished, in MacColl et al. 2021) with most of the difference between years being explained by complete nest failure caused by a cyclone in 2005 and increases in monitoring effort. Records south of Cape York Peninsula over the past decade are increasingly scant, although some places where recorded historically (e.g. Shoalwater Bay) have not been surveyed recently. An ongoing decline is therefore inferred, with habitat degradation and loss (the principal cause of losses over the past three generations) an ongoing threat.
Erythrotriorchis radiatus is endemic to Australia. Historically, it ranged in northern and eastern Australia, north of c.33°S in the east, and 19°S in the west, but its range has contracted in the east and it is now considered at least functionally extinct in New South Wales and South-east Queensland (Cooper et al. 2014, Seaton 2014, MacColl et al. 2021). Individuals are currently known to breed from the Kimberley east to Cape York Peninsula and north to the Tiwi Islands. They may also breed at very low densities in the Wet Tropics and Einasleigh Uplands although data are scarce. Records from central Australia (Aumann 2001) and the Pilbara (L. Trotter pers. comm.) probably include both dispersive juveniles (Aumann 2001) and seasonal migrants from further north based on non-breeding migration of satellite-tagged adult females, which have covered distances of 1,000 km to more southerly non-breeding home ranges. The Gulf Plains bioregion, formerly viewed as a dispersal barrier, is now considered readily surmountable, while satellite tracked adults and juveniles from Queensland and the Northern Territory soared to >1,000 m, suggesting the Tiwi Islands population is unlikely to be isolated by the narrow water barrier to the mainland (~27 km) (MacColl et al. 2021).
This species inhabits coastal and subcoastal tall open forests and woodlands, tropical savannas traversed by wooded or forested rivers, and along the edges of rainforest, usually on fertile soils (DERM 2012), but rarely breeds in areas with fragmented native vegetation (Aumann and Baker-Gabb 1991, Czechura 2001). Nests are in trees >20 m high and are commonly near to a watercourse or wetland (Aumann and Baker-Gabb 1991) within a breeding home range of at least 200 km2, where they mostly take medium to large size birds (Aumann and Baker-Gabb 1991). After breeding, some individuals move long distances and may occupy more inland open habitats.
Habitat clearance and fragmentation for agriculture and forestry are the major known threat (DERM 2012, MacColl et al. 2021). Agricultural and urban clearance is associated with declines in New South Wales and southern Queensland (Czechura and Hobson 2000, Czechura et al. 2011). Seasonal use of inland environments and some historical breeding (e.g. Macquarie Marshes, NSW 1951–1956, L. Harvey pers. comm.) indicates that loss of habitat and water resources in these areas may have also impacted these populations. Even if riparian strips are left uncleared, pairs usually nest in the tallest trees that are then exposed to storm damage and other disturbance. Clearing of forest for acacia plantations has rendered some territories on Melville Island unproductive (S. Garnett in litt. 2007). Although breeding success was reduced once >25% of forest and woodland was cleared for forestry within 4 km of nest sites on Melville Island (DERM 2012), no native vegetation clearing has occurred since 2008, and many of the monitored nests have been built in native vegetation along roads or firebreaks adjacent to plantations (S. Ryan unpublished, in McColl et al. 2021). Changed fire regimes (Czechura and Hobson 2000, Czechura et al. 2011, DERM 2012) may affect the availability of prey because woodland thickening impedes hunting efficiency (DERM 2012). A cyclone caused all five nests monitored on the Tiwi Islands to fail in 2005 but had a trivial effect on population viability (Hamel et al. 2008). Egg-collecting may result in the failure of some nests as does the burning of nest trees or disruption of breeding by fire. Inappropriate fire regimes causing the thickening of vegetation is also considered a threat (Red Goshawk Recovery Team in litt.). Shooting by pigeon and poultry owners, and possibly pesticides, causes some mortality of individuals and may result in temporary local scarcity (MacColl et al. 2021). Prey abundance may be reduced by loss or degradation of freshwater wetlands, loss of hollow-bearing trees in which prey breed, over-grazing by livestock and feral herbivores, and changed fire regimes.
Conservation Actions Underway
CITES Appendix II. Some survey work has been carried out in various parts of the species' range. The Red Goshawk Recovery Team is developing a plan to address actions in National Recovery Plan, including: establishing a central data-base of all records for the species, map essential habitat across the species whole range and determining mainland habitat-use and home-range patterns (MacColl et al. 2021). Some pairs nest within protected areas. Nests are monitored on Tiwi Islands.Conservation Actions Proposed
From Garnett et al. (2011), DERM (2012) and MacColl et al. (2021):
Identify important populations and monitor key indicator sites. Study demography, especially adult survivorship. Characterise critical habitat, including limits to habitat perturbation. Investigate the impact of habitat fragmentation and fire regimes on the spatial distribution of nesting pairs, their productivity and the abundance of prey. Improve knowledge of ecological requirements (e.g. habitats critical for survival) to more clearly inform management.
Limit access to known nest sites. Ensure developments do not reduce the goshawk population. Protect habitat through purchase or voluntary conservation agreements. Encourage landholders to protect and manage Red Goshawk territories. Promote information used to identify and protect nesting habitat. Ensure compliance staff are sufficiently knowledgeable to enforce conditions. Produce educational materials that promote the recovery process.
45-60 cm. Large, powerful, reddish-brown hawk. Adult has pale, dark-streaked head, two-tone underwing, rufous lesser and median coverts, with the remainder white with black barring. Adult male has rufous underbody. Adult female much paler and heavily streaked with black. Juvenile has rufous head. Similar spp. Distinguished from other raptors by boldly scalloped rufous upperparts and thighs, conspicuous on birds flying away from observer. Voice Variety of cries and chattering calls. Males are said to sound peevish and wheezy, females harsh and strident. Hints Search in open forest and woodlands, especially near rivers, in Top End and Kimberley regions.
Text account compilers
Berryman, A., Garnett, S., Vine, J.
Contributors
Baker-Gabb, D., Garnett, S., Harvey, L., Red Goshawk Recovery Team, Seaton, R. & Trotter, L.
Recommended citation
BirdLife International (2024) Species factsheet: Red Goshawk Erythrotriorchis radiatus. Downloaded from
https://datazone.birdlife.org/species/factsheet/red-goshawk-erythrotriorchis-radiatus on 23/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 23/12/2024.