What is That Noisy Bird That Goes ‘Ku-oo’ Every Morning?

You are trying to sleep in on a beautiful Saturday morning, but all you can hear is a crisp kooo-koooooo sound stemming from somewhere outside your window. You ignore it, but it keeps coming back every few seconds.


It is a slightly long drawn chirp of a bird. It must be a bird, but what bird? You toss in bed again and try to go back to sleep. After all, you have heard this sound your whole life. It is sometimes strangely comforting, but not today. Today, you needed to sleep in.


What exactly is this bird’s deal? How does it look like? You are suddenly overwhelmed with curiosity, but it is not accompanied by enough enthusiasm to trudge out of bed and look. You decide that you have lived almost three decades of your life wondering about the exact same question. But this question did not tug at your sleeves hard enough to be answered. Today, though, you had time to know.

You are thoroughly free, and increasingly awake. You scroll through social media like the millennial that you are, and become bored. There are no plans anyway since everybody is staying home. Prime Minster Lee Hsien Loong telling you to stay home, so you better listen.

Today, you want to know.

How should you even begin to search? How do you spell out a sound? Is it ku-ku, or ko-ko, or koo-koo? Or is it cuckoo? Koo-uuuu? You are crippled with choice. You pause and ponder for a second, and type:

“Singapore bird morning koo koo”

A truckload of search results pop out. Thank goodness, you are not alone.

It’s an Asian Koel!

That’s your answer, right there.

Mating calls

A male Asian Koel resting in the interior of a dense tree near you. (source)

Whether you live in an HDB, condominium, or landed property, regardless of its location in the north, south, east, west, or center of Singapore, you will hear this sound. Even while in an ulu camp at Tuas or Lim Chu Kang, this bird has been alongside you.

The Asian Koel’s call is a universal Singapore experience.

However, no bird chirps without purpose. The kooo-koooooo sound that the Koel makes is actually a mating call, and a desperate one.

The male Koel repeats a kooo-kooooo call in search of a female, which has a comparatively more shrill sounding kik kik kik call. How often do you hear the male’s call being responded to? Without any response, all the male Koel can do is to set its call on loop, hoping for a reply.

The Koel’s population is stable, and its species has the status of ‘least concern’. Being very commonly found in Singapore, it is sometimes difficult to believe that the Koel is a protected species under the Wild Animals and Birds Act. Anybody who kills, takes, or keeps them without a license can be fined up to SGD$1, 000.

It’s protected? But it’s everywhere!

Being a common species does not mean that it can be exploited. The Koel is widely seen throughout Singapore, but it has not always been the case. Up until the late 1980s, it was a non-breeding visitor, sometimes considered as a winter visitor.

The Koel became widespread in Singapore thanks to the house crow. As a member of the cuckoo family, the Koel is a brood parasite. This means that it makes use of other species of birds to raise their young.

The female Koel will eye an unguarded nest of a preferred and suitable host bird, which happens to be the house crow. When nobody is looking, the Koel may even push the other eggs out of its nest to prevent competition for its own young. When the Koel chick hatches, the house crow will continue to feed it like its own.

Even if Koel chicks live alongside house crow chicks, the house crow chicks are likely to die as the Koel chicks tend to be larger and louder when begging for food in comparison.

Over time, with more house crows in Singapore, more Koels settled in.

That’s kind of ruthless, no?

House crow feeding noisy Koel chicks as Koel parent speculatively watches on. (source)

While Koel brood parasitism seems crude and downright evil, it actually has a positive impact on the entire ecosystem. This parasitism ensures that the house crow’s reproduction success is kept at a healthy level, which in turn keeps the house crow’s population in check.

The next time you hear the unmistakably familiar kooo-koooooo, know that he is reaching out to a potential mate, who will proceed to destroy a family of house crows. Its young will then grow up and continue the mating mall as the cycle repeats, in a nest near you.


Vanessa Ng


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