Spot the difference: why drongos are likely to clock African cuckoo eggs 94% of the time

Zambia study finds egg variability and random nest selection by cuckoos helps fork-tailed drongos rumble impostors

Cuckoos might be the ultimate avian con artists, laying lookalike eggs in the nests of other birds to avoid raising their own young, but researchers say at least one potential victim is remarkably good at rumbling the fraud.

Scientists studying the African cuckoo have revealed that while the birds are able to produce almost identical-looking eggs to those of the fork-tailed drongo, the latter is likely to reject an impostor egg about 94% of the time.