Adaptive features in juvenal plumage pattern of the Indian Koel Eudynamys scolopacea: host mimesis and hawk-pattern

Abstract

The Indian Koel, Eudynamys scolopacea, a brood parasite, shows marked sexual dimorphism in adult plumage. While the males of the species show host-mimesis in plumage characters, females have a raptorial pattern in their plumage. However, the young female in the nest of its fosterers has a male-like appearance, obviously a morphological adaptation of much survival value. Adaptive features of the plumage contributing to the masking of the typical female pattern and to the host-mimesis have been studied. Juvenile males were also examined to ascertain the basic plumage type of the species. Comparison with other species of Cuckoos, both parasitic, reveals the significance of host-mimesis in the Koel nestlings. From the observations, it is proposed that the basic plumage pattern of the species is of the female type.