Cuckoo arms race

The cuckoo lays its eggs in the nest of an unwitting host species and after hatched, the parasite nestling often evicts the host eggs or young, ensuring maximum resources for itself. While some hosts recognize and destroy the cuckoo egg, defensive action against hatchlings has been underinvestigated. In the 13 March Nature, Naomi Langmore and colleagues at the Australian National University, Canberra, show that, in response to parasitism, the Australian superb fairy-wren stops feeding the bronze-cuckoo chick and abandons the nest, a strategy that can be outwitted by the right cuckoo call (Nature, 422:157-160, March 13, 2003).

Langmore et al. showed that once brooding had started, the decision to abandon an egg clutch hinged on seeing the female cuckoo at the nest, rather than the egg itself. Once hatched, the decision to abandon nestlings depended in part on the number of chicks in the nest —...