Internal incubation 'gives cuckoos head start in life'
CUCKOOS have confounded established science after researchers discovered their eggs are incubated internally, something biologists had thought impossible.
The fact female cuckoos can incubate their eggs before leaving them in the nest of another species mean they hatch first, giving the cuckoo chick a vital advantage.
Prof Tim Birkhead, from the department of animal and plant sciences at Sheffield University said: "The idea of internal incubation in birds has until now been considered impossible because it was assumed that female birds could not hold onto a fully formed egg.
"Our results show that internal incubation gives cuckoo chicks that crucial head start in life."