19-3-2015 JURONG, SINGAPORE - ASIAN KOEL (FEMALE) (Eudynamys scolopaceu)

 

The Asian koel (Eudynamys scolopaceus) is a member of the cuckoo order of birds, the Cuculiformes. It is found in the Indian Subcontinent, China, and Southeast Asia. It forms a superspecies with the closely related black-billed koels, and Pacific koels which are sometimes treated as subspecies. The Asian koel like many of its related cuckoo kin is a brood parasite that lays its eggs in the nests of crows and other hosts, who raise its young. They are unusual among the cuckoos in being largely frugivorous as adults. The name koel is echoic in origin with several language variants. The bird is a widely used symbol in Indian and Nepali poetry.

The Asian koel is a large and long-tailed cuckoo measuring 39–46 cm (15–18 in) and weighing 190–327 g (6.7–11.5 oz). The male of the nominate race is glossy bluish-black, with a pale greenish grey bill, the iris is crimson, and it has grey legs and feet. The female of the nominate race is brownish on the crown and has rufous streaks on the head. The back, rump and wing coverts are dark brown with white and buff spots. The underparts are whitish, but is heavily striped. The other subspecies differ in colouration and size. The upper plumage of young birds is more like that of the male and they have a black beak. They are very vocal during the breeding season (March to August in the Indian Subcontinent), with a range of different calls. The familiar song of the male is a repeated koo-Ooo. The female makes a shrill kik-kik-kik... call. Calls vary across populations.

The Asian koel is a bird of light woodland and cultivation. It is a mainly resident breeder in tropical southern Asia from Iran, Pakistan, India, Bangladesh and Sri Lanka to southern China and the Greater Sundas. They have great potential in colonizing new areas, and were among the pioneer birds to colonize the volcanic island of Krakatau. They first arrived in Singapore in the 1980s and became very common birds.

Some populations may make long-distance movements being found in places like Australia.

The Asian koel is a brood parasite, and lays its single egg in the nests of a variety of birds, including the jungle crow, and house crow. In Sri Lanka before 1880 it was only known to parasitize the jungle crow, later shifting to the house crow. A study in India found 5% of Corvus splendens and 0.5% of Corvus macrorhynchos nests parasitized.

In Bangladesh, they parasitise long-tailed shrike (Lanius schach), common myna (Acridotheres tristis) and house crows (Corvus splendens) at about 35.7, 31.2 and 10.8% rates respectively. Host nests at low heights and nearer to fruit trees tended to be preferred by koels. In southern Thailand and the Malay Peninsula, koels have shifted host from crows to mynas (Acridotheres sp.) as the latter became more common in the late 1900s.[16] In the Indian Subcontinent they have sometimes been found to parasitize the black drongo,[28] the European magpie and possibly the black-headed oriole. In the Philippines, Asian Koels have been found to parasitize the cavity nest of Coletos (Sarcops calvus). Males may distract the hosts so that the female gets a chance to lay an egg in the nest. More often however, the female visits the nest of the host alone. The koel is not known to lay eggs in an empty host nest and a study in Pakistan found that the first koel eggs were laid, on average, within one and half days of the laying of the host's first egg. The chicks of the koel hatched about 3 days ahead of the host chicks.[36] Koels usually lay only an egg or two in a single nest but as many as seven to eleven eggs have been reported from some host nests. A female may remove a host egg before laying. Eggs hatch in 12 to 14 days. The young koel does not always push out eggs or evict the host chicks, and initially calls like a crow. The young fledge in 20 to 28 days. Unlike some other cuckoos, the young do not attempt to kill the host chicks, a trait that is shared with the channel-billed cuckoos which are also largely frugivorous as adults.[40] It has been suggested[by whom?] that koels, like some other brood parasites do not evict the host chicks due presumably due to the higher cost of evicting nestmates. A small parasite may not be able to evict large host eggs or chicks from a deep Corvid nest without risking starvation and possibly accidental self-eviction. An alternative hypothesis that retaining host chicks might benefit the koel chicks did not gain much support. Adult female parents have been known to feed young koels in the nests of the hosts, a behaviour seen in some other brood parasitic species as well. Adult males have however not been noted to feed fledglings.