NT
Beach Thick-knee Esacus magnirostris



Justification

Justification of Red List Category
This species qualifies as Near Threatened because it has a small population. If the population is found to be in decline it might qualify for uplisting to a higher threat category.

Population justification
The population is thought to number c.5,000 individuals in Australia, 1,000 individuals in the Melanesian islands (G. Dutson in litt. 2002), and 10-20 individuals in New Caledonia. This totals at least 6,000 individuals, roughly equivalent to 4,000 mature individuals.

Trend justification
The population is suspected to be in decline owing to human disturbance and predation by invasive mammals.

Distribution and population

Esacus magnirostris is widespread around coasts from the Andaman Islands, India, Mergui Archipelago, Myanmar, islands off peninsular Thailand, and Peninsular Malaysia through Indonesia, Brunei, the Philippines, Papua New Guinea, the Solomon Islands, Vanuatu, New Caledonia (to France) and Australia. Its population in Australia may number c.5,000 birds and is probably stable (Garnett and Crowley 2000). Its density in Australia may have decreased locally on islands and in areas of the mainland where there are high levels of human disturbance and coastal development, especially around inhabited islands of the Great Barrier Reef and Torres Strait, and the wet tropical coast (Freeman 2003). Despite this, between the 1920s and 1970s the eastern part of the species' range appears to have extended south into New South Wales (Garnett and Crowley 2000). It is very rare on and around Sumatra and Vanuatu, where it has not been seen for six years (N. Barre in litt. 2003). Despite observation effort on many islets of the southern lagoon (“Ilots du lagon sud” IBA) and outside (Loyalty islands, remote islands IBAs) of New Caledonia, it has only been seen in the north (Chartendrault in litt. 2007). Even if probably partly underestimated because of remaining unexplored areas, the New Caledonian population seems very small and may be a relic, even if there is no visible trend (Chartendrault in litt. 2007).

Ecology

Pairs may be found on most beaches within its range; in Australia these include short stretches of muddy sand among mangroves, coralline sands on atolls and prime surf beaches (Garnett and Crowley 2000). Beaches associated with estuaries and mangroves are particularly favoured. In New Caledonia, it is breeding on coral islets inside the lagoon, mainly on dead coral beaches near fringing reef, on upper shaded areas (Chartendrault in litt. 2007).  Adults are sedentary, although the species has a tendency for wide-ranging vagrancy. It lays a single egg in a scrape in the sand at the landward edge of the beach, often using the same area repeatedly. It forages mainly in the intertidal zone on crustaceans and other invertebrates (Garnett and Crowley 2000).

Threats

The species appears to be threatened by extensive human disturbance of beach habitats in many areas (Garnett and Crowley 2000). It is also thought to be sensitive to predation by introduced mammals. Much of the species' habitat in Australia, particularly on islands, is secure. This species occurs at low densities and occupies linear habitats, increasing the potential for local extinctions to become regional ones; however, its apparent range expansion southwards in eastern Australia suggests that such extinctions do not represent genetic barriers (Garnett and Crowley 2000).

Conservation actions

Conservation Actions Underway
No targeted conservation actions are known for this species.

Conservation Actions Proposed
Maintain a register of inhabited beaches. Monitor population trends, especially where human disturbance is prevalent. If necessary, control the use of beaches by humans and their dogs, particularly during breeding. Determine the relationship between human disturbance and breeding success.

Acknowledgements

Text account compilers
Benstead, P., Garnett, S., Harding, M., Pilgrim, J., Symes, A., Taylor, J., North, A.

Contributors
Baudat-Franceschi, J., Freeman, A., Chartendrault, V., Barré, N.


Recommended citation
BirdLife International (2022) Species factsheet: Esacus magnirostris. Downloaded from http://www.birdlife.org on 26/09/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 26/09/2022.