If I wasn't a librarian, I might enjoy being a naturalist. Reading Cuckoos: Cheating by Nature by Nick Davies, I am impressed by the dedication of scientists who spend countless hours outdoors observing the behaviors of birds and other wildlife. Davies has spent over three decades doing such work in the fens outside Cambridge where he is a professor of behavioral ecology. He also takes trips to other sites in England and around the world to observe cuckoos and the birds that they victimize with their egg laying. What an interesting life!
What a strange and hard-to-understand bird! The cuckoo lays its eggs in the nests of other birds, so the foster parents raise the chicks. Is this good parenting? How many of the hosts fall for the deception and raise the cuckoo chicks instead of their own? Davies tries to answer these questions through conducting many experiments in the field. Many involve egg swapping.
Through his own observations and studies of cuckoos conducted over hundreds of years, Davies has come to some conclusions. One is that the host birds are not totally defenseless; they do sometimes reject the cuckoo eggs. Another is that there are numerous subspecies of common cuckoos in Europe that can only be identified by their eggs. One subspecies has eggs that resemble reed warbler eggss, another makes meadow pipit-like eggs, and so on. Their breeding success relies on getting their eggs into the right nests at the right times.
If the cuckoos were invariably successful, they would probably wipe out their host species. Studies show, however, that the common cuckoo is declining in number, as global warming is allowing their target species to nest earlier and earlier, but the cuckoos are returning from their winters in Africa at their tradition times, sometimes too late to lay their eggs unnoticed.
Davies has a fascinating subject and his reporting is lively and personal. Cuckoo should prove popular with natural history readers.
Davies, Nick. Cuckoos: Cheating by Nature. Bloomsbury, 2015. 288p. ISBN 9781620409527.