Data Zone
Justification of Red List category
This species qualifies as Near Threatened because the population size becomes moderately small at times of low habitat suitability, however estimates are based purely on frequency of encounter in a very large area with few observers and some modelling of habitat suitability.
Population justification
The population of Letter-winged Kites fluctuates greatly, potentially by more than an order of magnitude, between times when prey is abundant and times when it is scarce (Marchant and Higgins 1993, Aumann and Bellchambers 1999). The population size at maxima is largely unknown, but at minima (the driest times in the climatic cycle) is thought to approach 1,000 mature individuals (Pavey et al. 2021).
Trend justification
Population cycles appear to be linked to those of the principal prey, the plague rat Rattus villossimus, which has population explosions following high rainfall (Olsen 1995). These explosions in population and range rarely last for more than a year, after which the species's distribution again contracts (Garnett 1992). Reporting rates were highest when the arid zone had higher than average rainfall in 1999–2001 and 2011–2013, with numerous records from the eastern arid zone even in drier years suggesting that despite fluctuations, there has been no overall decline.
Letter-winged Kites are endemic to Australia and occur primarily in the eastern Australian arid zone, but occasionally irrupt to other areas of the arid and semi-arid zones, and dispersing individuals have been encountered at the coastal margins of all mainland states. The range is considered to have three distinct components: the core range, where individuals are always present and where they persist during prolonged dry periods when prey populations are low; the irruptive range, to which individuals move during each period of high resource availability; and the vagrant range, where the occurrence is unpredictable and often at some distance from the arid zone. The core range is poorly known with most records from the Cooper Creek drainage system and the Strzelecki and eastern Simpson Deserts. During wetter years they arrive in areas with high prey numbers to breed, but they do not persist for longer than 18–24 months and then may be absent for years (Reed and Reed 2012, Pavey et al. 2020). During the wetter periods, kites disperse widely across the eastern Northern Territory and river systems in south-western Queensland, north-eastern South Australia and north-western New South Wales, and can reach all parts of the continent (Marchant and Higgins 1993). Habitat suitability can fluctuate greatly, but models suggest at least 60,000 km2 has remained suitable in even the driest years since 1998 (Runge et al. 2015). While the locations of records vary greatly in extent and location between years, there is no evidence of any decline in range (Marchant and Higgins 1993, BirdLife Australia 2020, eBird 2020).
This is a largely nocturnal species (Garnett 1992), hunting at night, and tending to rest in coolabah trees Eucalyptus coolabah during the day (Olsen 1995). It inhabits open or sparsely wooded country, usually in flocks, but also seen as pairs and singles (Johnstone and Storr 1998). They roost, nest and sometimes hunt in groups, and often form large noisy breeding colonies of up to a hundred individuals (Olsen 1995). They nest in the cooler months when the rats often reach their peak, with nesting peaking in July. The nest is an open platform of sticks from herbage and shrubs. They lay clutches of 2-7 eggs and the incubation period is thought to be 31 days. The age at fledging is five weeks. When breeding, anecdotal accounts suggest that the main prey species is the long-haired or plague rat Rattus villosissimus; however, this has not been substantiated by quantitative studies. Further, breeding has been observed at multiple locations in the absence of this prey species. Prey species include house mice Mus domesticus, native rodents and small marsupials, reptiles and invertebrates (Baker-Gabb and Pettigrew 1982, Pavey et al. 2008a, 2008b); however, the species should be considered a rodent specialist. High rainfall is followed by explosions of prey species populations during which time kites can fledge several clutches in succession, and the population can increase rapidly (Marchant and Higgins 1993).
There are no known major threats, although competition for prey with foxes Vulpes vulpes and cats Felis catus, may reduce breeding productivity (Pavey et al. 2008a, 2008b). Also, some refuges for prey species in non-boom periods may be overgrazed or trampled by cattle, horses, donkeys Equus asinus and camels Camelus dromedarius (Pavey et al. 2017). Cats climb trees and may take nestlings, but the demographic impact of this predation remains unquantified (Olsen 1995). While conditions in the core range are predicted to become warmer and drier over the next 50 years (Larkin et al. 2020), the current absence of monitoring means changes to abundance cannot currently be detected. The species is listed under CITES Appendix II, albeit the exact scale of trade is unknown.
Conservation Actions Underway
CITES Appendix II. No other targeted conservation actions are known for this species.
Small, pale kite, similar to Black-shouldered Kite Elanus caeruleus. Black spot in front of eye. Underparts white. Upperwing coverts and alula coverts black. Primaries dark grey. Tail white with central feathers tinged grey. Rest of upperparts pale grey. Underwing white to greyish white with black bar from axillaries to base of primaries. Iris red; bill black; cere horn-coloured; legs pink or whitish (Johnstone and Storr 1998).
Text account compilers
Vine, J., Garnett, S., Taylor, J.
Contributors
Akers, D. & Mathieson, M.
Recommended citation
BirdLife International (2024) Species factsheet: Letter-winged Kite Elanus scriptus. Downloaded from
https://datazone.birdlife.org/species/factsheet/letter-winged-kite-elanus-scriptus on 23/11/2024.
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 23/11/2024.