Why do international research and management?

Abstract

The pheasant, in its North American range, seems to have had its greatest success in glaciated or in other areas associated with calcareous soils. Success has been slight in areas deficient in calcium.....In Lancaster County, Pennsylvania, no environmental difference other than presence or absence of limestone was discovered that might explain the high population in the limestone valley and the scarcity of pheasants in the non-calcareous Piedmont area....Pheasants at the Patuxent Refuge, when given limestone grit, reproduced successfully on a diet roughly comparable to the natural pheasant diet but failed to reproduce adequately on such a diet when granite grit, instead of limestone, was supplied.....A supplement of powdered calcium carbonate in the diet was adequate t,o permit production of eggs by birds on the granite grit.....Birds receiving granite grit had apparently normal eggs in the ovary but failed to ovulate more than a very few eggs. The precise role of calciun~i n permitting ovulation was not investigated.....It is concluded that calcium, which is low in the natural pheasant diet, must be supplemented in some way to permit pheasants to reproduce. Scarcity of this element in non-calcareous areas may well explain the failure of the pheasant in many parts of North America.