Mother always knows her chicks

A study led by ANU has discovered how a mother knows her chicks and can spot an imposter in her nest, even if it looks almost identical to her chicks. Brood parasitic cuckoos lay their eggs in the nests of other birds and abandon their young to the care of the nest's host, leading to significant disruptions to the birds involved. A research team from ANU and The University of Sydney studied the large-billed gerygone, a small songbird that is invaded by the little bronze-cuckoo, in Cairns, Australia. Large-billed gerygones usually evict cuckoo chicks from their nests within a few hours of hatching. Senior researcher Professor Naomi Langmore said the study aimed to find out how the large-billed gerygone recognised cuckoo chicks.  "Cuckoos pose a major threat to the hosts - when the cuckoo chick hatches, it evicts all the host eggs from the nest," said Professor Langmore from the ANU Research School of Biology. She said some hosts had evolved the ability to recognise and evict the cuckoo chick. "Theory predicts that evicting cuckoo chicks based on their physical appearance poses the real risk that the bird could evict one of its own chicks, so the bird supposedly uses indirect cues such as the invading chick being alone in the nest," Professor Langmore said.