A hawk-like bird flew in and sat on a broken branch of a small tree in front of us as we walked along a mud-track of Barotopa village in Mawna, Gazipur. The bird neatly folded its grey wings on its back and looked squarely at us. There was neither fear nor threat in its goggle eyes. A pair of Bulbuls panicked all the same and left the tree promptly.
The bird's grey wings and the barred brown belly made us think for a moment that it was a Shikra, the most common hawk of the villages. Then we looked at its slender yellow toes with tiny nails and its unhooked bill. We thought: no, not a Shikra. A Shikra has sturdy toes with deeply curved nails to kill small animals and a hooked bill to tear flesh.
We saw the soft yellow eye-rings and the gracefully graduated tail feathers of the bird on the branch and concluded that it was a Common Hawk-Cuckoo; not a Shikra. Evolution has shaped this sneaky cuckoo to impersonate the fierce Shikra, probably, because that provided some protection against the attacks from their mean neighbours.
The English bird-men working in India centuries ago named that bird 'Common Hawk-Cuckoo' because it visibly mimicked the hawk and was the most common cuckoo there. The bird still is common only in the Indian Subcontinent and rarely seen elsewhere. Even in the Subcontinent the secretive bird is not easily seen; people become aware of it in the spring only when the male starts singing aloud: 'pee-peah, pee-peah...'
'Brain-fever bird' is the other English name for Common Hawk-Cuckoo. That name came from the cuckoo's loud and long repertoire rising in a crescendo at every step of its song: 'brain-fever, brain-fever, BRAIN-FEVER, BRAIN-FEVER'. The song usually stops abruptly after the loudest canto and starts afresh after a short break.
For the Common Hawk-Cuckoo, every language of the Subcontinent has a unique name crafted out of an imaginative transliteration of its song. The nifty Bangla transliteration 'chokh-gelo' means 'eyes pine', ostensibly, for the beloved. The unabashedly romantic Hindi transliteration 'piya-kaha' means 'where is the beloved'. The banal Marathi transliteration 'paos-ala' meaning 'rain is coming' often proves oracular during the monsoon.
Suddenly the Common Hawk-Cuckoo left the small tree in front of us, probably, to escape our ogling and click-clicks of the cameras. It flew like a hawk with intermittent wing-beats and landed nimbly on an Acacia trunk. We could see its wide, undulating and striking tail-bands which clearly proclaimed that it was indeed a Hawk-Cuckoo; not a Shikra. The tail-bands of the Shikra are faint, straight and narrow.
Soon the Cuckoo merged with the tangles of the trees and managed to dodge our peering eyes and cameras. A small troop of Jungle Babblers descended from the grove to forage on the ground below. We realised that the Cuckoo was hiding more from the Babblers, who happen to be their foster parents.
While desiring forever to remain unseen, the Common Hawk-Cuckoo certainly did not mind being heard. We heard its long, loud and tuneful song 'pee-peah, pee-peah...' everywhere on our long walk in Barotopa and the neighbouring villages. We remembered a few charming lines of William Wordsworth's poem titled 'To The Cuckoo':
O Cuckoo! shall I call thee Bird,
Or but a wandering Voice? …
Thrice welcome, darling of the Spring!
Even yet thou art to me
No bird, but an invisible thing,
A voice, a mystery;
Indeed, the Common Hawk-Cuckoo desires very much to be a voice and a mystery. In the village groves, the Cuckoo clearly wished to stay invisible and anonymous, especially to the small bands of Jungle Babblers. The blithe Babblers of Barotopa village were happily babbling and bouncing between trees since it was the high season for them to make a nest, love and merry.
As the village grove reverberated with 'pee-peah, pee-peah...' of the males the female Cuckoos cooked a secret plan to lay their eggs in the nests of unwary Babblers. The Cuckoo females did not wish to incubate their own eggs and rear their hatchlings. The Babblers, Orioles and Shrikes have been doing those chores for them for aeons.
Happily, the Cuckoo-hatchlings could thrive quite well on tiny insects the Babblers, Orioles and Shrikes bring home to their chicks. Once fledged the Cuckoo-chicks learn to swallow large, poisonous and hairy caterpillars and regurgitate the hair as pellets - an ability well beyond Babblers, Orioles and Shrikes.
The prolific Jungle Babblers have been pretty good at raising their own families besides fostering the Common Hawk-Cuckoo chicks. The clever Cuckoo lays a single egg in each nest; the Babblers raise the Cuckoo-chick along with a few of their own. The Babblers have an exceptional habit of feeding all hungry chicks in the neighbourhood.
The population of Jungle Babblers in Bangladesh has been falling drastically in the recent past. That worrying fall is not attributable to the nest-parasitism of the Cuckoo; but directly to the indiscriminate destruction of insects through our frenzied use of chemical insecticides, pesticides and herbicides.
The nest-parasitism has survived successfully for at least 50 million years to the benefit of the Cuckoo while its foster parents, though cuckolded, have suffered in no other way. The unwise usage of chemicals in our environment, on the other hand, has done irreparable damage to the populations of both the Cuckoo and the cuckolded Babblers in a mere hundred years.