Cuckoo in egg pattern 'arms race'

Cuckoos' egg forgery skills are increasingly being put to the test, as host birds evolve better defences, say scientists.
These brood parasites, as they are called, are master deceivers - hiding their eggs in other species' nests.
To avoid detection, cuckoos have evolved to mimic colour and pattern of their favoured host birds' eggs.
But researchers have developed "birds eye view" models ... This study revealed details about the "evolutionary arms race" in which cuckoos are embroiled; as they evolve better mimicry, their hosts evolve the skills to spot these damaging intruders.