Esacus is a genus of bird in the stone-curlew family Burhinidae. The genus is distributed from Pakistan and India to Australia. It contains two species, the great stone-curlew and the beach stone-curlew.
The genus Esacus was introduced (as a sub-genus) in 1831 by the French naturalist René Lesson to accommodate the great stone-curlew.[1] The name is from Ancient Greek aisakos an unidentified bird variously associated with a robin, a shorebird or a cormorant. In Greek mythology Aesacus was a son of King Priam of Troy. Aesacus sorrowed for the death of his wife or would-be lover, and was transformed into a bird.[2]
The two species are larger and heavier-set than the stone-curlews of the genus Burhinus. They resemble small bustards, especially in flight, and have long and heavy bills and long legs.[4]
The beach stone-curlew is found in coastal areas, as its name suggests, seldom found far from the coast. The great stone-curlew also favours water, often found close to large lakes or on the river shore. Like the Burhinus stone-curlews the great stone-curlew is nocturnal, but the beach-stone curlew is less so, and feeds during the day on beaches and islands.[4] The beach curlew is found from the Andaman Is through Indonesia to Australia and New Caledonia.[5] The great stone-curlew is found from coastal Iran and Pakistan through central India, Burma, Thailand to Hainan in China.[6]
They feed on crabs and other invertebrates; the great stone-curlew uses its large bill to overturn stones to find prey, and the beach stone-curlew uses its bill to break up crabs and eat them, which it catches by stalking them like a heron.[4]
The Esacus stone-curlews make harsh wailing calls. The great stone-curlew is a seasonal breeder, timing it before the start of the monsoon. The timing of the beach stone-curlew is more variable across its large range.[5] The beach stone-curlew is the only member of the family not to lay a clutch of two or three eggs, and lays a single egg.[4]