The Influence of Calcium on the Distribution of Pheasants in Illinois

Abstract

The role of deficient calcium as a factor limiting the distribution of pheasants (Phasianus colchicus) in Illinois was investigated by comparing the availability of calcium and its subsequent inges- tion by wild pheasants on an area (Neoga) of old glacial till originating from the Illinoian glacial age and on an area (Sibley) of more recent till originating from the Wisconsin glacial age. The amount of calcitic grit, and the amount of calcium contained in the calcitic grit, collected from roads and agri- cultural fields on both areas were similar, as were the amounts of calcium found in the soils from the two areas. The amounts of calcium found in the grit from gizzards of hens and young from both areas were very similar. The number and hatchability of eggs per incubated clutch, the production of chicks per hen, and the ash content of femora and of entire carcasses of hens during the nesting season were similar among pheasants at both Neoga and Sibley. Wild pheasants, particularly hens and young, seemingly possess the ability to select (1) calcareous grit from noncalcareous grit, (2) calcitic grit from dolomitic grit, and (3) calcitic grit with a high calcium content from that with a low calcium content; this habit of selective calcium ingestion may allow pheasants to prosper on areas where cal- careous grit is found only in relatively small quantities. The availability of calcium and its subsequent ingestion by pheasants at Neoga, an area of old glacial till, are apparently adequate for the establishment of self-maintaining pheasant populations.