Big, loud and looking for a mate - Asian Koels in Hong Kong

As dawn cracks and you wake up to prepare for work, school or other routines, your day may go undisturbed without a sharp two-toned “koo-ah,” courtesy of the Asian Koel (Eudynamys scolopaceus), a common sight in Hong Kong.

Steady into Spring, the cacophonous calls of the Asian Koel echo throughout Hong Kong, signalling the mating season for the city’s feathered friends.

With a vocalisation akin to their onomatopoeic name, the Asian Koel is a large, long-tailed cuckoo species common in Hong Kong and widely distributed throughout East, South and Southeast Asia. Although they are resident birds, they are only heard vocalising during the breeding season, typically between March and August.

“I’ve seen some people imitate their sounds whenever I visit the park,” said birder John Chow Kwok-pun. “Some people don’t even recognise what bird is making those noises.”

The “ko-ah” call is produced by the male koels, which sport glossy black plumage, to attract females, identifiable by their white and black streaks. Like certain bird species, such as herons and hawks, they have crimson irises.

Asian Koels can be found in urban parks and the countryside, perched high in the trees where they vocalise. Being mainly fruit-eaters, they can also be observed perched near fruit trees.

“They are frugivorous birds, which means they can be good seed dispersers,” said Bond Shum, founder of Outdoor Wildlife Learning Hong Kong.

“Frugivorous birds mainly take fruits in their diet and they can fly with a larger foraging range which helps to disperse the seeds further away from the mother tree,” said Shum. “With the protection of an indigestible seed coat, the seeds are excreted and dispersed when the birds fly away from the fruiting tree.”

Asian Koels also possess the behavioural pattern of brood parasites. Brood parasitism is observed among cuckoo species where a female cuckoo lays eggs in the nest of another bird species, leaving all parental care of her young towards the host bird.

A female Asian Koel would deposit her eggs in unattended nests, and the host bird may not recognise the foreign eggs, depending on the mimicry of the female’s eggs and the host’s ability to tell the difference.

Baby koels typically hatch first. While some brood parasites are known to remove host eggs by pushing them out of the nest, koel chicks often coexist with the host chicks, according to research by PLOS One, a journal published by the Public Library of Science.

Nonetheless, the bigger koel chick often outcompetes its “siblings” in receiving food by begging persistently.

Chow, who also hosts birding tours, said that he finds sharing the koel’s behaviour inspiring for new birdwatchers.

“Whenever I tell people about their parasitic way of life, it makes them wonder, creating curiosity and allowing them to explore more about our wildlife,” he said.

While some may appreciate the koel’s calls and songs, others may find them annoying.

“From January to March this year, we received 12 complaints regarding noise nuisance caused by birds, including the Asian Koel,” said Joyee Chan, fauna conservation officer at the Agriculture, Fisheries and Conservation Department.

The AFCD noted on its website that the calls of the Asian Koel may cause disturbances to some people living nearby.

“In general, we would advise all complainants that all wild birds, including their nest and eggs, are protected by the Wild Animals Protection Ordinance,” said Chan.

“Some tenants may complain to the housing management, but in fact, we should live with them in harmony as we have taken over their habitat,” said Chow.

“Although Asian Koels or other wildlife in the city may cause problems to us, such as noise during the breeding season, they are still part of our neighbourhood. We cannot exclude them. Let’s try to have more empathy as they are doing the most important things in their life,” said Shum.

Hong Kong has recorded over 570 different species of birds, according to the AFCD, and Asian Koels are of “least concern” on the IUCN Red List.