The sweet coo-coo of the Koel reminds most of us of lazy childhood summers with songs and stories. Excerpts from mythological folklore and household lores of just how sweet the Koel is, the word “sweet” not only referring to her melodious song, but also to her overall “sweet nature”. The Koel finds mention in ancient scriptures, including the Manusmriti, an ancient decree which elevates the cuckoo bird to a highly protected status. Now, before we get bowled over by the pious and pretty voices, let’s just find out how “sweet” and “sacred” exactly this dainty bird is.
The Asian Koel is a brood parasite, which means that it lays its eggs in the nests of other birds and leaves its young ones to be bred and brought up by other birds. The earliest mention of this behaviour seems to go back to Sanskrit literature dated 2000 BC, where the Koel was referred to as “Anya-Vapa”, translated as “that which was raised by others” or “sown for others to reap”. This phrase is nothing but a depiction of its brood parasitism behaviour. Now how exactly does it achieve such a stroke of mastermind? Definitely not by chatting with and convincing the host bird to act as foster parent! It is a well-designed strategy that the male and female Koel execute to perfection- they are partners in crime!
Amongst the most common targets that are at the receiving end of these parasitic tactics are the house crow, the shrike, the myna and the drongo. In short, the selection of the host seems to be a factor of abundance–the more the availability of the hosts, the more its chances of being taken advantage of by the Koel. The Koel’s first preference seems to be the house crow due to its commonalities. Similar colour, size and the similar appearance of eggs makes it hard for the host parent to detect that there’s a foreign egg (and then a foreign chick) sharing space and food with its own kith and kin.
Once the courtship with its loud calling and clamour is over, it’s time for Mommy and Daddy Koel to go in search of the perfect foster home for babies. Nests that are built on lower-placed branches and covered by dense vegetation and surrounded by fruits are preferred by the Koel. This is because the Asian Koel is primarily a frugivore, subsisting preferably on fruits. However, it may turn to being omnivore by eating insects, caterpillars etc. especially when small. The male Koel sets about his duty, singling out host parents who have painstakingly spent hot afternoons building nests. He then distracts the parent crows (or other host birds) and diverts their attention elsewhere. In the meanwhile the mother goes to the nest and lays a single egg or maximum two, in the host bird’s nest. The female Koel’s body is designed to contain the egg in the body till the time she is able to sneak into a foreigner nest. In some cases, the female may remove a host egg and then lay hers in place of it. Maybe she thinks it best not to take the risk of a headcount check by foster mommy! The incubation period of the Koel ranges between 13 to 16 days, whereas that of the crow is between 17 to 20 days. A Koel is seldom seen to lay eggs in an empty host nest, to match the hatching time of the host and the parasite chick perfectly. What clever timing!
After gestation, the Koel chick hatches. It is known to mimic the sounds of the crow hatchlings. Master con men they are, right from birth, they dupe the adult host birds into believing that their own young ones just made it into the world! Sometimes, a clever host bird may identify the difference, in which case the nest is generally abandoned by the host crow. But in most cases, parental instinct takes over, and the crow feeds and raises the Koel chick as its own, along with its own! Crafty and shrewd that they are, the Koel’s duty does not end with laying the eggs. Often, the Koel duo looks over the host nest from afar, making sure that their young one is being showered with care and love. If they do not see that happening, they may even destroy the whole host nest! Or the female Koel mother may take it upon her to feed her chicks in the host nest. They do not dispense their parental duties, but act as if they have the authority to “supervise” other parents!
Now that’s parenthood without the pain and pressure of raising kids! And the Asian Koel has mastered this art to the hilt, by way of morphological design and behaviour! Nature has its own deceptive ways, not everything in nature is as it looks or seems. So look for yourself and decide how truly “sweet” nature’s creations are, or is there an element of bitter-sweet in them!
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