Witnessing Brood Parasitism

I had heard of Brood Parasitism from other birders. But getting to actually witness it in action definitely requires luck. And luck did favour me once for it.

What are Brood Parasites? Brood parasites are organisms that rely on others to raise their young. This is a behaviour exhibited by some birds, insects and even fish. Birds that are brood parasites will lay their eggs in the nests of the other breeding birds. The unsuspecting foster parents are then allowed (or maybe saddled?) to raise the young. There are a number of adaptations that they use for this. Some species mimic the shape and colour of the host’s eggs. The chick parasite once hatched will often kill the host’s chicks or remove the eggs in the nest. This is to increase its chance of surviving. Yes, it does sound gruesome. But such are the ways of nature I guess. However nature also has its balance. The hosts are not completely helpless. They also co-evolve behaviours like abandoning a nest if they have parasitic chicks. But then some hosts seem to be able to raise chicks of both their own and that of a parasite. In birds, Cuckoos, Koel, Cowbirds and some ducks are the popularly known brood parasites.

On an outing to Hulu Langat when I based in Kuala Lumpur, Malaysia, I was given the opportunity to witness a juvenile of a Violet Cuckoo being raised by a Red-throated Sunbird; a classic case of Brood Parasitism. There was a pair of Red-throated Sunbirds and a lone Violet Cuckoo juvenile. The cuckoo juvenile was seen constantly making a shrill call, I guess reminding its foster parents of their duty to feed it 🙂 . Whenever the female sunbird came to a closeby branch, the cuckoo would start to flutter its wings vigorously. Finally, the sunbird would come and feed it.

Here are some photos I was able to capture of the sequence.

Many questions came to my mind once we left the place. Was the sunbird aware that it was raising another bird’s chick? The cuckoo juvenile was visibily larger than it! What had happened to the sunbird’s own chicks? There were none to be seen around. Whatever were the answers it had been exciting to get to witness it happening in front of ones eyes.

Did you know that there are Wasps that also exhibit brood parasitism like the Cuckoos? You can read about one such one here.

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