title: Visual mimicry of host nestlings by cuckoos.
abstract: Coevolution between antagonistic species has produced instances of exquisite mimicry. Among brood-parasitic cuckoos, host defences have driven the evolution of mimetic eggs, but the evolutionary arms race was believed to be constrained from progressing to the chick stage, with cuckoo nestlings generally looking unlike host young. However, recent studies on bronze-cuckoos have confounded theoretical expectations by demonstrating cuckoo nestling rejection by hosts. Coevolutionary theory predicts reciprocal selection for visual mimicry of host young by cuckoos, although this has not been demonstrated previously. Here we show that, in the eyes of hosts, nestlings of three bronze-cuckoo species are striking visual mimics of the young of their morphologically diverse hosts, providing the first evidence that coevolution can select for visual mimicry of hosts in cuckoo chicks. Bronze-cuckoos resemble their own hosts more closely than other host species, but the accuracy of mimicry varies according to the diversity of hosts they exploit.
authors.affiliation: Research School of Biology, Australian National University, Canberra 0200, Australia. naomi.langmore@anu.edu
authors.forename: Naomi E
authors.initials: NE
authors.lastname: Langmore
authors.forename: Martin
authors.initials: M
authors.lastname: Stevens
authors.forename: Golo
authors.initials: G
authors.lastname: Maurer
authors.forename: Robert
authors.initials: R
authors.lastname: Heinsohn
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Hall
authors.forename: Anne
authors.initials: A
authors.lastname: Peters
authors.forename: Rebecca M
authors.initials: RM
authors.lastname: Kilner
mesh_terms: D000220:Adaptation, Biological; D000818:Animals; D001315:Australia; D005075:Biological Evolution; D001717:Birds / Q000254:growth & development / Q000502:physiology*; D006790:Host-Parasite Interactions; D009425:Nesting Behavior; D020308:Songbirds / Q000502:physiology*; D013045:Species Specificity; D014796:Visual Perception