Erythrotriorchis radiatus

This species has been downlisted from Vulnerable because its population is now estimated to be larger than was previously thought. Nevertheless, the population remains moderately small and is suspected to be declining, with most individuals restricted to a single subpopulation, and it is therefore listed as Near Threatened. Good evidence of continuing, moderately rapid population declines might lead to it being uplisted again in future.

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 from south of 28°S in the east, and it is now virtually extinct in New South Wales. Recent surveys suggest breeding is continuous across northern Australia. The population was estimated at only 330 pairs in the early 1990s, but was estimated at 700 pairs in 2010, including 100 pairs on Tiwi Islands, probably a separate subpopulation, and 600 pairs elsewhere across northern Australia from the Kimberley through the Northern Territory and through Queensland to northern New South Wales (Garnett et al. 2011). Gradual declines owing to loss of habitat may still be occurring, at least in eastern Queensland (Garnett et al. 2011).

Because of its inconspicuousness, the population size is probably historically under-estimated. The total popula­tion was previously estimated at about 350 pairs, but is now estimated at about 700 pairs. This includes 100 pairs on Tiwi Islands, probably a separate subpopulation, and 600 pairs elsewhere across northern Australia from the Kimberley through the Northern Territory and through Queensland to northern New South Wales (Garnett et al. 2011).

It lives in coastal and subcoastal, tall, open forests and woodlands, tropical savannas traversed by wooded or forested rivers and along the edges of rainforest. It builds stick nests in trees taller than 20 m within 1 km of a watercourse or wetland. It hunts in open forests and gallery forests, with a home range of up to 200 km², taking mostly medium to large birds, but also snakes. In winter in eastern Australia, it appears to move from nest-sites in the ranges to coastal plains, where it often feeds on waterbirds taken from open wetlands.

Widespread clearance for agriculture probably caused the historical decline in north-eastern New South Wales and southern Queensland. Continuing clearance is affecting more northerly 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). Egg-collecting may result in the failure of some nests as does the burning of nest trees or disruption of breeding by fire. Shooting by pigeon and poultry owners, and possibly pesticides, causes some mortality of individuals and may result in temporary local scarcity. 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.