The noisy first cuckoos of summer the eastern koels (Eudynamys orientalis) have arrived in Canberra, flying in from the northern rainforests of Indonesia and Papua New Guinea to feast on backyard grapes, figs and plums.

The suburbs are ringing with the piercing, repetitive two-note call (ko-will! ko-will!) that's earned this cuckoo the colloquial name of ''brain-fever bird'' in parts of Asia.

Canberra ornithologist and bird photographer Geoffrey Dabb said, ''Many Canberrans are hearing them for the first time this summer, and wondering what is making such a racket. Koels are common down along the coast, and around Sydney at this time of year, but their range appears gradually to be extending further south.''

It's not climate change that's caused this southward shift. It's Canberra's fondness for ornamental plums as street trees, backyard fruit trees and grapevine-covered pergolas that's attracted these fruit-eating summer migrants.

Canberra seemed to have an influx of young male koels this year, looking to establish new territories, Dabb said. The males were calling for females, and could start their mournful ascending call as early as 3am and ''go like mad for hours''.

''Their call carries for over a kilometre, and if there's one calling in a tree near your house, you're probably not going to get much sleep.''

The frequency of calls will taper off after Christmas, as adult birds move away from the nests they've parasitised. Female koels lay eggs in the nests of a numerous host birds usually red wattlebirds that incubate the eggs and feed the chicks when they hatch.

''They kill off the host bird's young, but there's no threat in this as the host birds are common species.''