More about Koels
The Eastern Koel is a large cuckoo that arrives in Australia from south-east Asia to breed in spring. Koels arrive in September or October and depart again in March.
Although rarely seen, Koels are well known to many Australians for their loud, repetitive calls, which are particularly noticeable early in the morning.
Breeding behaviour
Like most other cuckoos, Koels do not build their own nests or incubate their own eggs. Instead, females lay their eggs in the nests of other birds. These 'hosts' incubate the eggs and feed the resulting young after they hatch. As Koels are large cuckoos, the young are frequently around twice the size of the foster parents that feed them. For example Koels weigh around 190 g, compared with 95 g for the Olive-backed Oriole and 90 g for the Magpie-lark, two of its common hosts. Other hosts that have been recorded include the: Black-faced Cuckoo-shrike, Blue-faced Honeyeater, Figbird, Grey Shrike-thrush, Helmeted Friarbird, Little Friarbird, Noisy Friarbird, Red Wattlebird, Silver-crowned Friarbird, Spangled Drongo, Victoria's Riflebird, White-bellied Cuckoo-shrike and Yellow-throated Miner.
Territorial behaviour and calls
Male Koels occupy a home range of perhaps 75 ha (although this is poorly known), in which they advertise their presence by repeated calling, mostly with the 'ko-el' call. They also produce a 'wurroo-wurroo-wurroo' call and there is some evidence that the latter call becomes more common later in the breeding season. Females are attracted to the male's calls and they produce a 'keek-keek-keek-keek' call of their own. Sometimes females will sing in a duet with the male's 'wurroo-wurroo-wurroo' call, resulting in a 'keek-wurroo-keek-wurrooo-keek-wurroo-keek-wurroo-wurroo'! After copulation, the female lays a single egg in the host's nest. The same female lays eggs in the nests of numerous hosts and these may be within the same, or a different, male's home range.
Increasing abundance of Koels
Koels eat fruit as well as insects, and they are particularly common in rainforest habitats, which tend to have a higher proportion of fruiting plants. They also appear to be becoming more common in cities, such as Sydney and Brisbane, perhaps because of the abundance of ornamental plants and weeds that produce berries. However, another factor that probably contributes to their increasing abundance is the proliferation of some of their hosts, particularly the Red Wattlebird.
References
Higgins, P.J. (ed) 1999. Handbook of Australian, New Zealand and Antarctic Birds, Volume 4 (Parrots to Dollarbird). Oxford University Press, Victoria.
Maller, C.J. 2001. Vocal behaviour of the Common Koel, Eudynamys scolopacea, and implications for mating systems. Emu 101: 105-112
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