The Role of Calcium in Reproduction of the Ring-Necked Pheasant

Abstract

ants in various major areas of North America seems largely understandable, certain localized aspects of this bird's distribution have continued to puzzle wildlife biologists. In southeastern United States, summer temperatures generally are assumed to be too high to permit reproduction (Graham and Hesterberg, 1948; Bennitt and Terrill, 1940; Yeatter, 1950). Lack of water is recognized as a potent limiting factor in the West, where ringnecks are restricted to irrigated areas. In midwestern and northeastern states, however, no clear-cut relationship has been established between pheasant distribution and any ecological factor. Pheasants are relatively abundant in southeastern Michigan but are rare in most southwestern counties of the State. Similarly, in southern Iowa, western Wisconsin, southeastern Ohio, and the cornbelt lands of Illinois and Indiana, populations of ringnecks are lower than would be expected on the basis of food and cover relationships. Ecological studies in these states have done little to explain failure in areas that appear from superficial surveys to have suitable habitat. Leopold (1931) suggested that glaciation might in some way influence success of the pheasant in the Lake States. He believed that some factor such as lime might be supplied in glaciated areas, but did not present any experimental evidence in support of this belief. This idea was furthered by McCann (1939), who demonstrated the superiority of glacial gravel over quartz as grit, but showed that quartz supplemented with calcium carbonate was adequate.