| Channel-billed cuckoo | |
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| Channel-billed cuckoo in a fig tree | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Cuculiformes |
| Family: | Cuculidae |
| Genus: | Scythrops Latham, 1790 |
| Species: | S. novaehollandiae |
| Binomial name | |
| Scythrops novaehollandiae Latham, 1790 | |
| Synonyms[2] | |
Scythrops psittaceusKerr, R. 1792 | |
Thechannel-billed cuckoo (Scythrops novaehollandiae) is a species ofcuckoo in the familyCuculidae. It ismonotypic within the genusScythrops.[3] The species is the largestbrood parasite in the world, and the largest cuckoo.[4]
It is found inAustralia,New Guinea andIndonesia; additionally, it isvagrant inNew Caledonia andNew Zealand. The species ismigratory over part of its range. There are threesubspecies, one migratory, the other two resident. The species is listed asleast concern by theIUCN.
CaptainArthur Phillip wrote of this (at the time) mysterious bird—calling it the 'psittaceous hornbill'—in his 1789 workThe voyage of Governor Phillip to Botany Bay, consulting with ornithologistJohn Latham and deliberating that it had features of a parrot, hornbill or toucan, though conceding there were no toucans in the region.[5] He gave it the nameScythrops novaehollandiae in 1790.[6][3] Its generic name is derived from theAncient Greekskuthro-/σκυθρο- 'angry' or 'sullen', andops/ωψ 'face', 'eye' or 'countenance'.[7] The specific epithetnovaehollandiae means ofNew Holland, hence Australian.[8]John White, the surgeon-general of theFirst Fleet to New South Wales, wroteA Journal of a Voyage to New South Wales in 1790, including this bird, which he termed 'anomalous hornbill".[9]
Threesubspecies are recognised:[10] the nominateScythrops novaehollandiae novaehollandiae of Australia, New Guinea and theMoluccas,Scythrops novaehollandiae fordi inSulawesi, andScythrops novaehollandiae schoddei in theBismarck Archipelago.[11]
Theonly member of the genusScythrops, the species is most closely related to thelong-tailed cuckoo (Urodynamis taitensis), which breeds inNew Zealand and winters in thePacific islands, according to Sorenson and Payne (2005).[12]
"Channel-billed cuckoo" has been designated as the official common name for the species by theInternational Ornithologists' Union (IOC).[10] Latham gave it the name "channel-bill" after a groove in its upper mandible[8]
The world's largest cuckoo, the channel-billed cuckoo measures between 56–70 cm (22–28 in) long, with a 88–107 cm (35–42 in) wingspan, and weighing between 560–935 g (1.235–2.061 lb).[13] 24 adults were found to have averaged 684 g (1.508 lb) in body mass.[14] According to a manual on avian body masses, another species of cuckoo, thebuff-headed coucal, may have a mean body mass some 11% higher than the channel-billed cuckoo.[14] Thebill is bi-coloured, with a grey base becoming straw-coloured at the tip. The bill is large slightly curved and reminiscent of the bills ofhornbills; in fact, the bird is sometimes erroneously referred to as a hornbill.[15] Theplumage of the adult is pale grey on the head, chest, belly and back, becoming paler and barred lower down on the belly. The wings are darker grey with dark tips on the feathers. The tail is dark grey on top and barred underneath with a black band and white tip at the end. The feet and legs are black, and the eye is surrounded by prominent red skin. While most other very large cuckoos are rather terrestrial (i.e.roadrunners or the genusNeomorphus), the channel-billed cuckoo is fairly arboreal and is capable both in trees and on the ground.[16] The channel-billed cuckoo is a strongflier, with a distinctive, almost hawk-like cross-shaped (cruciform) flight silhouette.[13] There is somesexual dimorphism in both plumage and dimensions, the female having a smaller bill and paler, more barred undersides.
The juvenile is similar to the adult but has pale tips to the feathers of the wings, and the rest of the plumage is buff instead of pale grey. The bill is less massive and dirty pink in colour, and the skin around the eye is not red.
The channel-billed cuckoo has a widespread distribution across northern and easternAustralia,New Guinea, theBismarck Archipelago, and the islands of easternIndonesia as far west asSulawesi. The species is a permanent resident in the Bismarck Archipelago,Flores and Sulawesi. Elsewhere within its range it ismigratory. Birds breeding in Australia range from north easternWestern Australia through theNorthern Territory andQueensland down into easternNew South Wales as far asSydney. In recent years, the breeding range of these cuckoos appears to have extended further down the south coast of NSW. A few stragglers reach the eastern tip ofVictoria, but are not thought to breed there.Vagrant birds have reachedNew Zealand andNew Caledonia.[17][18]
After the breeding season, in March and April, birds breeding in Australia begin to migrate northwards to their wintering grounds in New Guinea and Indonesia. Birds breeding in New South Wales begin leaving earlier, in February and March.[19] The migration route is across theTorres Strait, travelling individually or in small groups. From New Guinea they migrate across the nearby islands as far as Timor and theMoluccas. It is not known if the species breeds in New Guinea, as some birds are present there all year. Migrating channel-billed cuckoos begin to return to Australia in August and September.[19]
The channel-billed cuckoo is often shy, remaining hidden in tree canopies feeding on fruit and most active in early morning and evening. Its loud raucous call makes it more often heard than seen. Other birds such as crows harass and chase it when they encounter it.[13] Miner birds and crows and some other species also swoop them.
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Channel-billed cuckoos arebrood parasites; instead of raising their own young, they layeggs in thenests of other birds. They are thought to formpair bonds for the duration of a breeding season.[20] Their mating behaviour has been described as involvingcalling and gift-giving, with the male presenting items of food such asinsects to the female. Pairs also work together in order to aid the laying of eggs in host nests; the male will fly over the nest in order to provoke the nest occupants into amobbing response, whereupon the female will slip into the nest and lay an egg. Alternatively the pair may work together by attacking anincubating bird, driving it off the nest and allowing the female to lay.
The host species varies depending on the location; the most commonly targeted hosts areravens,currawongs,butcherbirds andAustralian magpies.[21] Several eggs can be laid in a single nest, sometimes by different females. Often resembling those of currawongs and magpies (but not ravens), the eggs vary in colour and pattern, measuring 48 x 32 mm. They can be a reddish- or yellowish-brown to dull white, with darker brown splotches.[22] The incubation period for this species is unknown. Upon hatching the chicks arealtricial, being blind and naked. Unlike many other cuckoos, the chicks of the channel-billed cuckoo do not eject the other host eggs upon hatching or kill the host's chicks, but these seldom survive as the cuckoo chick is able to monopolise the supply of food. The chicks are fully feathered within four weeks, and leave the nest to clamber about on the branches, although chicks are fed for a number of weeks by the host parents afterfledging.
Unusually for cuckoos, which generally take insect prey, but like the closely relatedkoels, fruit forms a major part of the diet of channel-billed cuckoos.[23] Fruits taken include those of several species ofFicus, including Moreton Bay fig (F. macrophylla), Port Jackson fig (F. rubiginosa), cluster fig (F. racemosa), strangler fig (F. watkinsiana) and sweet sandpaper fig (F. opposita), the fruits of trees in the mistletoe familyLoranthaceae as well as the fruits of theintroduced black mulberry (Morus nigra).[24] Also taken are insects, including beetles, butterflies and grasshoppers, and the nestlings and eggs of birds, includingapostlebirds,magpie-larks andnoisy miners. Birds typically feed in the canopy of large trees, sometimes in groups and occasionally with other fruit eating birds such asAustralasian figbirds andcuckoo-shrikes.
In northern Australia their migration coincides with the beginning of therainy season, leading to the species being given a range of colloquial names such as storm-bird, flood-bird or rain-bird.[17] The frugivorous habits of the species, coupled with its raptor-like appearance, have also resulted in it being known as the fig hawk.[8]
The channel-billed cuckoo is not consideredthreatened by human activities, and as such is listed asleast concern by theIUCN.[1] In fact, it has benefited from human activities; along with theAustralian koel its numbers have increased in some parts of its range due to increases in host species caused by extensive planting of gardens around Australian cities.[25]
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