But often the cuckoo mom gets away undetected ... a retired photo editor who’s an avid wildlife photographer, observed the birds’ behavior in 2014 in Amsterdam, where she lives.

In a clip from the episode, Attenborough said: 'Katharina Huchler is about to become a foster mother, and these are her new babies, 28 of one of the world's rarest birds, Northern Bald Ibis.