Bird Communal Display Grounds - Page 1

Display is highly elaborate in species with less traditional social systems, such as the Lekking species, which use communal display grounds. Male display territories in these species are small sites on the display rounds. Because these territories do not provide for the nest or food for the young, the female's choice of a mate depends on the physical characteristics of the male. As a result, the sexes in most lekking species have evolved great differences in size, plumage, and other adornment.

Natural selection has long favored males in lekking species with larger, brighter, or more ostentatious decorations. The neck pouches of the Greater Prairie-Chicken or the purple neck pouches of the Sage Grouse are examples of male adornments in lekking species. In both species the male inflate their pouches to enhance their remarkable displays.

The male Greater Prairie-Chicken displays with its head bent forward, its ear tufts raised, its throat pouch expanded, its wings held close and aquiver, and its tail broadly fanned. In this posture the bird steps and turns around the display grounds, all the while producing a resonant, booming sound. Females that visit the lek choose among males on the basis of this display and on the male's relative location in the lek. The birds mate quickly, before a rival male can disrupt them, and then the female leaves to nest elsewhere. In this brief encounter no real pair-bond is formed, and the male has no participation in raising the young.

Many other males of the Grouse, Quail, and pheasant family have developed elaborate plumage to dazzle the females in display, as in the famous tail spread of the peacock. The many species of birds of paradise of Papua New Guinea, however, rank as the world's most extreme examples of specialized and gaudy male plumage.