Species: Asian Koel Eudynamys scolopacea
Other common names: Koel, Common Koel, Indian Koel, Malayan Koel, Black Cuckoo, Koel Cuckoo.
Taxonomy: Eudynamys scolopacea (Linnaeus) 1758, Malabar. Eudynames = Eudinamys = Eudynamis = in errore.
Sub-species & Distribution: Fifteen sub-species are currently recognised, extending its range from Pakistan and India, Sri Lanka and much of SE Asia to China, the Philippines, Thailand, West Malaysia, Singapore, Sumatra, Java and the Sunda islands. Three races are found in this region:
Separating the races: Morphometric measurements listed in early books vary enormously, probably due to the mixing of specimens of different races. Male birds are generally inseparable in the field. Females can be separated, with some difficulty.
Size: 15½ to 17" (39 to 43 cm). Sexes differ.
Description: Male: Entirely black with dark metallic blue gloss, appearing purplish at times. It looks like a crow with a very long tail at first glance. When in moult, some old feathers fade to reddish-brown.
Female: Upperparts dark blackish-brown, with some gloss, heavily spotted with white, rufous and buffy-rufous. Ear coverts darker brown, rufous malar stripe, sides of face, forehead, crown streaked rufous, extending to nape, sometimes extending onto chin and throat in younger birds. Wings and tail barred rufous-buff with whiter spots on tips of feathers. Underparts dirty white to pale buff, throat and foreneck paler streaked blackish-brown, and narrow blackish-brown bars on lower belly, vent, thighs and flanks.
Immature birds: Nestlings are uniformly black at first but moult quickly to look like adult females, their crown feathers with broad rufous shaft-stripes, the white spots and bars strongly tinged with rufous to buff, the throat with broad whitish streaks, the breast with large white spots, and the abdomen with dark marks (Oates & Blanford 1895). Young males are dull slate with buff tips on feathers of breast, belly and wing (Payne & Sorenson 2005). Young males often have coverts faded blackish-brown and tipped with white, the unmoulted wing feathers sometimes retaining residual white barring, and paler tips to the edges of primaries and wing coverts.
Soft parts: Iris bright red. Bill dull yellowish-green, darker and bluish along the edges of both mandibles, inside mouth red. Tarsus bluish-grey, soles buff.
Status, Habitat & Behaviour: A common resident and winter visitor, to about 750 m (2500 feet). In the 1920's, it was thought to be a very rare bird in Singapore (Robinson 1927), as a non-breeding winter visitor in small numbers but the resident population has increased since 1987 (Wang & Hails 2007).
Arboreal in habit, the Koel can be found in coastal mangroves, orchards and lightly wooded areas in parks and gardens around cultivation, towns and villages, but rarely in large forests. It is a shy bird and easily overlooked during the winter months when it remains silent and unobtrusive. When watched, it works its way quietly through dense foliage to the other side of a tree, then flying off (Davison 1874 - see notes under Miscellaneous:). It is rarely found on the ground, and only briefly seen in the open, when furtively dashing from cover to cover. All too often, only the male is seen, the female remaining even more unobtrusive. In Singapore, however, they are more regularly seen at this time since the local population is augmented by a large number of winter migrants.
It is only during the breeding season that their presence becomes very obvious and evident. Its call is usually the first to be heard at dawn, while it is still dark, and they even call late into the night. They are also seen regularly being harried by crows trying to protect their nests from intruding Koels.
Its flight is strong and direct, with faster wing beats than that of true cuckoos, enabling it to easily evade pursuing crows. It can sometimes be seen sunning itself on top of a tree early in the morning.
Food: In India, its food consists chiefly of fruit and berries from a variety of trees and shrubs, Peepal or Sacred Fig Ficus religiosa, Banyan Ficus benghalensis, Camphor tree Cinnamomum camphora, Ber or Indian Plum Zizyphus mauritiana, Indian sandalwood Santalum album, Ivy gourd Cephalandra indica = Coccinia grandis, Mulberry Morus spp., nuts of the Fishtail Palm Caryota urens, the poisonous fruit of the Yellow Oleander Thevetia neriifolia and nectar from Coral Tree Erythrina indica (Ali & Ripley 1969). It also takes caterpillars, Hemiptera bugs, other insects, snails and birds' eggs stolen from nests (ibid.).
It also takes fruit of the Buffalo Thorn Ziziphus mucronata, Guava Psidium guajava, Brazilian cherry Eugenia uniflora, Wild Caper Capparis sepiaria, Tamarind Tamarinda indica, Wild Jujube Ziziphus oenoplia, Chandada Macaranga peltata, Pepper Piper nigrum, and nuts of Oil Palm Elaeis guineensis and Alexandra Palm Archontophoenix alexandrae, as well as insects such as grasshoppers, mantids, stick insects (Payne & Sorenson 2005) and fruit of the Bakul Mimusops elengi tree (Jerdon 1862).
In Singapore, it has been seen eating fruit from the Indian cherry Muntingia calabura (Tsang & Wee, Y.C. 2007), Australian Mulberry Pipturus argenteus and papaya Carica papaya (Meng et al 2008), rambutan Nephelium lappaceum (D'Rozario & Wee, J. 2010), Great Morinda or Noni Morinda citrifolia (Wee, Y.C. 2007), and completely swallowing the Alexandra Palm Archontophoenix alexandrae fruit (Lam 2007). It regurgitate the large seeds of any fruit it has eaten (Jerdon 1862, Chua et al 2009).
Voice and Calls: Though normally silent, it becomes particularly vocal during the breeding season, its loud, melodious and penetrating whistle being heard throughout the day and night. The dissyllabic call note, kuoo (Ali & Ripley 1969), with stress on the longer and louder second syllable, repeated several times, increases in intensity and runs up the scale with each successive note, until it reaches a definite crescendo, then breaks off abruptly. Shortly, it starts calling all over again.
Its call is variously given as ku-il ku-il (Jerdon 1862), who-are-you? who-are-you? (Harrington 1909), you're-ill, you're-ill (Dewar 1915), ku-oa (Salim Ali 1941), and ke-woo (Payne & Sorenson 2005).
Several other notes are described: a ho-whee-ho or ho-a-o or ho-y-o uttered by the male (Jerdon 1862), a series of accelerating vyuk vyuk phrases and an excited bubbling kwow kwow-kwow-kwow call (Payne & Sorenson 2005) rather like that of the female Common Cuckoo Cuculus canorus.
Breeding: The Koel, being a cuckoo, is brood parasitic and does not build a nest. Instead, it lays eggs surreptitiously in the nests of several host species, its choice of victim varying from location to location.In 1927, it was almost certain that the bird did not breed in Singapore (Burknill & Chasen 1927). Since 1987, however, breeding has become widespread, and mating has been recorded in April and June, nestlings in January, April and October, and immature birds in March and November (Wang & Hails 2007). In Kelantan, eggs were found in the nest of a Large-billed Crow C. macrorhynchus in February (Robinson 1927) and breeding was said to be common in the Klang valley by 1985 (Wells 1999).
The House Crow Corvus splendens is the usual victim in Singapore (Wells 1999), as well as in India where several other species are cuckolded, Common Mynas Acridotheres tristis (Baker & Inglis 1930), Golden Orioles Oriolus oriolus (Ali & Ripley 1969) and Large-billed Crows (Oates & Blanford 1895). In Myanmar, it is the Common Magpie Pica pica (Harrington 1909), Jungle and Slender-billed Crows C. enca in Java, Common and White-vented Mynas A. javanicus in Thailand (Payne & Sorenson 2005), Magpies of genus Urocissa and Starlings of genus Graculipica in China (Baker 1927). As a result, Koels are frequently harassed and mobbed (Amar-Singh 2011) by several species of birds.
Its eggs are very much like those of the Crow, but slightly smaller. In colour, the eggs come in varying degrees of green, from pale greenish-yellow to greyish-green, profusely speckled and blotched with reddish-brown. Baker (1927) was of the view that the colour varied to some extent to match that of the hosts' eggs. One hundred eggs had an average size of 31.0 x 23.6 mm (Baker 1927).
Though male Koels are known to proclaim their territory with loud ku-il calls, very little is known of their courtship behaviour. In Singapore, rival males have been seen posturing with loud kwok-kwok-kwok cries and intermittently confronting one another with open flapping wings and fanned tails (Wee 2007). In India, a male was seen feeding its mate with berries plucked off the trees on which both were sitting (Finn 1917). Courtship feeding has also been recorded both in Singapore (Tan 2010), and at Ipoh, in Malaysia, a male fed its mate with the fruit of a Neem tree Azadirachta indica (Amar-Singh 2008).
To enable the Koel to lay an egg within a crow's nest, a devious game of strategy takes place between two protagonists - the male and female Koel on one side, and the two crows on the other. Firstly, the male Koel stations itself very close to an active crow's nest, calling loudly and boldly to advertise its presence. The crows, despite their fame for cleverness and cunning, and having a seemingly inbuilt hatred of the opponent, promptly give chase to the intruder. Meanwhile, the female Koel, lurking nearby under dense cover, quietly waits until the crows are far enough away, then slips quietly in to lay her egg directly into their nest within a few seconds.
In India, the female usually lays just after the host has laid its first egg (Payne & Sorenson 2005). The Koel's breeding season usually corresponds with that of its usual host and, during a single season, the female lays several eggs in as many nests. It generally lays one egg in each nest it visits (Jerdon 1862).
Whether or not the female Koel destroys the hosts' eggs remains unclear. Jerdon (1862) said it mostly, but not always, destroys the eggs. Oates & Blanford (1895), on the other hand, said that two or more Koel's eggs may frequently be found in the same nest, possibly laid by more than one female.
Baker (1927) had found as many as 13 Koel's eggs in one nest, and was of the view that female Koels do not always destroy the victim's eggs, since many observers have seen young Crows and Koels in the nest together. However, he does add that he has never seen Crows feeding more than one young Koel.
It was suggested that, like other cuckoos, Koel hatchlings eject the young Crows after they are hatched (Oates & Blanford 1895) but the evidence is largely circumstantial. Like Baker, Hume (1890), too, had found a young Cuckoo in a nest with three young Crows, all freshly hatched. A week later, the young Crows were "missing" and the young Cuckoo thriving. It has been said suggested that the Koel's egg, having a shorter incubation period (13 to 14 days vs 16 to 20 days in crows), hatches first, enabling the Koel nestlings to lower the breeding success of the host, and even evict host eggs and young from the nest (Payne & Sorenson 2005).
The nestling period is 19 to 28 days and newly fledged young cuckoo are fed by its foster parents for another two to three weeks (Payne & Sorenson 2005). Hume (1890), having repeatedly watched female Koels feeding young of their own species, was "pretty nearly convinced that after laying their eggs the females keep somewhere about the locality and take charge of the young directly they can leave the nest". Jerdon (1862), however, doubted this to be the general practice. The begging call of young Koel fledglings are loud trills and squeaks, wheeet-oop-wheeet-wheeet-wheet-op, as well as high-pitched screeches, with no apparent mimicry of begging call of the hosts' young (Payne & Sorenson 2005).
Migration: Night-flying migrants were captured at Fraser's Hill on 6 October 1969 and 31 October 1970 (Medway & Wells 1976) and birds were seen at unlikely locations, including on Perak Islands, up to 23 December (Wells 1999). Hails (1988) listed the bird as an uncommon winter visitor found in Singapore between 22 September to 26 April.
Miscellaneous: William Ruxton Davison, considered one of the best Indian ornithologists, was the curator of the Raffles Museum in Singapore from 1887 to 1893. In the 1870's, as a collector under A. O. Hume, he travelled to the Tenasserim along border between Myanmar and Thailand where he collected 8,600 specimens. In 1875, Hume honoured Davison by naming one of the birds collected in the Tenasserim after him, the White-shouldered Ibis Pseudibis davisoni. A form of the Crested Serpent-eagle Spilornis cheela davisoni, from the Andaman Islands and, possibly also on Nicobars, was also named after him, as was Praying Mantis Parymenopus davisoni Wood-Mason 1890. Davison died in 1893.
In India, Koels were often kept in cages by those who admired its "rich melodious call notes" (Oates & Blanford 1895). The European population, however, found the call to be "irritating" (Harrington 1909), "a positive nuisance" (Barnes 1885), "a maddening shriek" (Harrington 1909), and a "most unpleasant cry" (Baker 1927) that, "on moonlight nights, delights to keep the worn-out Anglo-Indian awake" (Baker & Inglis 1930). The Koel has sometimes, incorrectly, been referred to as the Brainfever bird. The actual owner of that name is the Common Hawk-Cuckoo Hierococcyx varius.The Koel's song evoked in Rudyard Kipling a great sense of nostalgia. In his poem, In Springtime (Kipling 1919), he wrote:
Measurements: (in mm) of one bird from Sg. Buloh, Singapore, another from the Turtle Islands in Sarawak (Sreedharan 1996, 1997).