International Journal of Comparative Psychology

The behavior and adjustments of a cuckoo nestling developing in a redstart nest were studied. High acoustic sensitivity was found in the range of non-species-typical components of the sonic feeding complex of the host species. The general tendency of avian hearing development, accelerated formation of low-frequency range, also plays an important role in the biology of the parasite species. A constantly increased level of feeding motivation along with the high acoustic sensitivity are basic for the 100% responsiveness to arrivals of adults with food. Vocalization matching, that is, a coincidence of the frequency band limits and of the intensity of vocalization of a cuckoo chick and redstart brood ensures the equal frequency of feedings. The coincidence of sequence and timing of the periods of nest life of cuckoo and redstart young that were determined with respect to the change of the modality stimulating feeding behavior increases the feeding competition abilities of a cuckoo nestling in the case of forced coexistence with the young of the host species.