On the leafy branches of the African tulip tree in front of my house in Koramangala, Bangalore, I hear the koel, beginning with a low koo, rising in scale with each successive koo-oo, till it reaches a crescendo and ceases abruptly, only to start all over again.

In verse after verse, our poets praise this super songster, calling it kokila. But the koel, as everyone knows, is dashed clever. It deposits its eggs in the nest of the crow and scampers off, leaving the mama crow to incubate its eggs and raise little koels.

The story of what the poets’ darling, the koel, does, especially when very young, is less known. The little koel, soon after it is hatched by the foster mother crow, struggles about until it gets under one foster brother crow, then climbs back directly up the open side of the nest. Then it nudges the crow brother over the rim. And plop, the little crow falls, all the way to the base of the tree, dead on arrival.

Then the little koel nudges another brother crow hatchling. One after another, all the little crows are thrown from the nest. But the little murderer grows, repeats its parasitic ways, and goes ku-oo-oo, tugging at poets’ heartstrings.

Our unsuspecting foster mother crow victims should learn from Europe’s common water mussel, a freshwater bivalve that plays host to Bitterling carp fish. In the breeding season, the fish develops a long tube — an ovipositor — by means of which she introduces her eggs into the gills of the mussel. The eggs soon hatch, and the infant fish swim away. But the mussel contrives to play a return match, a tit for tat, by forcing the fish to play foster mother. The mussel violently ejects its own fry into the water at the same time that the fish is foisting its eggs. The young mussels have toothed shell that pierce the fish’s skin and become embedded in the inflammation set up by their presence. Here they remain till they grow larger and burst the walls of the cysts. Then, they happily descend to the bottom of the stream.

... contd.