Researchers at the University of Sheffield have discovered that cuckoo eggs are internally incubated by the female bird for up to 24 hours before birth, solving for the first time the mystery as to how a cuckoo chick is able to hatch in advance of a host's eggs and brutally evict them.
Published today (22 September 2010) in the journal Proceedings of the Royal Society of London, Series B, the research shows that internal incubation allows the cuckoo chick to hatch before its nest mates, evict them, and monopolise the food brought by the foster parents.