A host-race difference in begging calls of nestling cuckoos Cuculus canorus develops through experience and increases host provisioning.
The structure of common cuckoo nestling begging calls differs between the two host-races parasitizing reed warblers (reed warbler-cuckoos) and dunnocks (dunnock-cuckoos; longer syllable duration, lower peak and maximum frequency, narrower bandwidth). Cross-fostering experiments demonstrated that this difference is not genetically fixed but develops through experience. When newly hatched reed warbler-cuckoos were transferred to dunnock nests, they developed begging calls more like those of dunnock-cuckoos, whereas controls transferred to the nests of robins or left to be raised by reed warblers developed calls more typical of reed warbler-cuckoos. We tested the effectiveness of these different calls in stimulating host provisioning by placing in host nests a single blackbird or song thrush nestling (of similar size to a young cuckoo, but lacking its exuberant begging calls); when it begged we broadcast, from a small loudspeaker on the nest rim, recordings of either dunnock-cuckoo or reed warbler-cuckoo begging calls. Playback of dunnock-cuckoo begging calls induced higher levels of provisioning by dunnocks, whereas playback of reed warbler-cuckoo begging calls did so for both reed warblers and robins. We suggest that the young cuckoo (which ejects the host's eggs/chicks and so is raised alone) learns by experience which calls best stimulate host provisioning.
Madden
Joah R
JR
Department of Zoology, University of Cambridge, Cambridge, UK. jrm54@cam.ac.uk
Davies
Nicholas B
NB
D000818:Animals; D001717:Birds / Q000502:physiology*; D005247:Feeding Behavior / Q000502:physiology*; D005260:Female; D006790:Host-Parasite Interactions; D008425:Maternal Behavior / Q000502:physiology; D013045:Species Specificity; D014828:Vocalization, Animal / Q000502:physiology*