India, May 17 -- Every morning at Lodhi Garden, beneath an ageing semal tree, a strange domestic drama is unfolding between hornbills that do not quite belong together.

There is the resident Indian grey hornbill family - a species common to Delhi - nesting inside a tree cavity. And there is the outsider: a lone female Oriental pied hornbill, a bird not typically found in the capital, arriving each day to feed the chicks inside as though they were her own.

What began as an unusual sighting has turned stranger by the day - a tale of adoption, territorial conflict, and, by Saturday morning, apparent infanticide.

"This is becoming a complete psycho-drama of sorts," said birder Sheila Chhabra, who spent two consecutive mornings observing th...