An old man requested us to check through our binoculars if a snake was sitting coiled up on the low branch of a young Pakur tree bordering the cremation ground at Muhuri Dam. We checked and were thrilled to spot a female Koel watching us from its little fortress of green foliage of the tree.
We were too near the Koel for her comfort. So, we backed off quickly, entreating the old man to follow us. Then, standing behind a line of Dholkolmi plants, we watched the Koel go about her business. The old man was delighted to watch her through the binoculars for the first time in his life.
The happy Koel soon picked fruit and went for more after devouring it. In early February, well before the usual fruiting season, the young Pakur tree had quite a few ripe fruits for her. That explained why the wary and stealthy female came down to that small tree and did not leave when we went near.
We continued to stand frozen behind Dholkolmi plants perchance a male Koel came courting the furtive female. No male came, but the female broke her cover and sat on a leafless part of the tree before flying into the dark canopy of larger trees. We got a clearer view of the secretive female for ten seconds.
We know how lucky one must be to have a clear view of a female Koel. She works very hard to live her entire life hidden behind the green curtain of the foliage. She works even harder to remain hidden from other birds than from the goggling people like us.
The female Koel has a 'good' reason to remain hidden from the other birds. She has plans to lay her eggs in the nests of a few of them without their consent. And she targets not some feeble, timid and washed up birds; but intelligent, strong and aggressive ones like crow, shrike and myna.
Stealth and espionage, therefore, are the two toolkits the Koels cannot do without. From the foliage cover, a female Koel must spy on several nesting pairs of her target birds throughout spring and summer. In a single season, she needs five, six or more nests to secretly lay her eggs in. She lays only one per nest.
Like every other bird, the Koel cannot lay an egg at an hour's notice. An eggshell is formed only by travelling through the reproductive tract for 20 hours. A female Koel has to anticipate at least a day in advance the opportune moment to sneak in and lay her egg in the nest of a pair of hostile birds.
The female Koel, therefore, must fly furtively from tree to tree to watch the lifestyle and the daily routine of many nesting pairs of birds simultaneously. She needs to observe them well and remember every detail so that her body prepares to lay eggs at the right moment on the right days. She does not have the luxury of sitting in a nest for hours and letting her body do the job gently.
The male Koel wanders about alone and is of no help to the female's intelligence gathering and other chores. He sings out loud and long. Unless the male sings in nearby trees, the female body does not release hormones to initiate egg production. The long process of egg-making would be a huge waste if there were no males around to fertilise it.
Like all cuckoos, the male Koel proclaims his presence by singing from foliage cover. His familiar refrain is 'koo-Ooo.. koo-Ooo..' which is why we call him Kokil. We hear his sweet song often but do not get to see his stunning blue-black body. Borrowing from poet Wordsworth, we can only pose him this question:
Shall I call thee Bird,
Or but a wandering Voice?
Dhaka city attracts hundreds of Koels because thousands of crows breed here every summer. Many nifty female Koels plan to lay their eggs in the crows' nests because the crows are intelligent, inquisitive and intrepid; therefore, they are easily distracted.
Even when incubating the eggs, the crow cannot resist the temptations to fly off to investigate every commotion, cry or screech in the area it inhabits. That opens wonderful opportunities for the female Koel to sneak in and lay her egg in the crow's nest.
Unlike several other brood parasitic birds, the Koel ejects or eats no egg from the nest she parasitizes. The Koel chick also ejects no egg or chick from the nest. All it wants is a head-start, and the chick ensures that by quickly hatching in 10-12 days, well before the crow eggs hatch. It often grows up in a crowded nest.
The female Koel does not forget about her brood after laying her eggs in the nests of other birds. Secretly she visits all those nests and sometimes feeds her hungry chicks. Contrary to all the bad press she got, the female Koel is a hell of a hard-working mother.
For millions of years, Koels have been using this bizarre parenting scheme - leaving the duty of incubation and chick-rearing to utterly unrelated and unwilling birds. Of the eleven thousand species of birds in the world, only about a hundred practice this anomalous method.
Although this method evolved naturally and has persisted over crores of years, we see no singular benefit in it. Clearly, parasitized birds such as a crow or shrike get no benefit from it. The cuckoo, on the other hand, has to live a secretive life and work real hard to pull off the awkward trick.
We can only imagine how challenging, perilous and stressful the life of a female Koel is. We weep when we see the crows crying over a dead chick with light brown bars on its feathers. Unlike the crows, we recognize it as a Koel chick and know that a female Koel is crying silently somewhere in the foliage of a nearby tree.