Back on 6 November 1976 I'd had a call from a friend of mine (no mobiles in those days) saying that he had found a Yellow-billed Cuckoo that morning at Pennington Marsh on the Hampshire coast of the UK. It wasn't seen again and ever since I had wanted to see one well. Not just brief flight views but to be able to study it. And this was the moment..
I didn't know anything about their ecology so had to look it up. Only sometimes do they lay their eggs in other birds’ nests, they don’t do this nearly as often as the Common Cuckoo of Eurasia, which made the behavior famous. When outbreaks of cicadas, tent caterpillars, gypsy moths, and other prey create an abundant food supply, Yellow-billed Cuckoos then sometimes do lay their eggs in the nests of other cuckoos as well as in those of American Robins, Gray Catbirds, and Wood Thrushes. And that explains the calling - it must have had a nest nearby.
They also have one of the shortest nesting cycles of any bird species. From the start of incubation to fledging can take as little as 17 days! Although born naked, the young birds develop quickly; within a week of hatching the chicks are fully feathered and ready to leave the nest.
And if you live outside the UK and are not familiar with the Cuckoo that we get here in summer in alarmingly diminishing numbers you can read a rather salutary piece written here by wildlife champion and writer, and wonderful photographer Paul Sterry.