They are also known as the Common Hawk-cuckoo:
Common because they can be found throughout India, Pakistan and Sri Lanka.
They eat insects and are especially well adapted to taking those caterpillars that are so hairy they hurt your hand. The Common Hawk-cuckoo has strong guts that separate the nice from the nasty so that the bristles can be coughed up as a pellet.
It's just like how owls deal with bones and fur, but I never imagined such a procedure would be necessary for caterpillars!
Except that they're not so harmless. They are brood parasites, like many other Cuckoos. Their chosen victims are a few species of babbler. A single egg is laid in the host nest. Once it hatches, the chick will usually set about murdering it's step-siblings by kicking out the other eggs. The poor foster parents will then feed this invasive killer for several weeks.
Now, I'm not at all sure if those babblers really sound like the cheerful gurgle of a babbling brook. I do, however, know that the Brainfever Bird has a maddening cry that sounds almost exactly as I feel when I have a terrible flu.
Other interpretations have the same sense of frenzy. The Marathi one translates to "the rains are coming". The Hindi to "where's my love". The Bengali is worse of all, it translates to "my eyes are gone".
My eyes are gone... My eyes are gone... My eyes are gone! MY EYES ARE GONE!! MY EYES!!! WHERE ARE MY EYES!?