476: Horsfield's Hawk-Cuckoo Nestlings Simulate Multiple Gapes for Begging -- Tanaka and Ueda 308 (5722): 653 -- Science
Nestlings of some brood parasitic birds evict hosts' eggs and young soon after hatching, thereby avoiding discrimination by hosts while monopolizing parental care. Eviction carries a cost, however, because lone parasitic nestlings attract a reduced provisioning rate. Here we describe a form of visual signaling used by the evicting Horsfield's hawk-cuckoo (Cuculus fugax) to obtain sufficient food. The chick displays a gape-colored patch on the wing to the host parents as they deliver food, simulating the gaping display of more than one nestling.
Coevolution of a nest parasite and it's host.