An Analysis of the Bird Population in the Vicinity of Rupert, Idaho

Abstract

Less than thirty years ago the area under consideration-the northern half of the Minidoka Irrigation Project, Minidoka County, Idaho--was virgin land, the haunt of the coyote, badger and Sage Hen, a land of drifting sand and sage. But great changes were initiated by that life-giver of the desert, water; and within a few years a thriving agricultural community had been established. The bird population, faced with these changing conditions, kept pace in its transition with that of the environment. New kinds appeared; others faded from the picture. Kenagy (Condor, 16, 1914, pp. 120-123) and Davis (Murrelet, 4, 1923, pp. 3-4) have pointed out some of the alterations that took place. It is my plan to analyze the native bird population as it appeared to me during the years 1919-1921. The data for this study consist of sight records made during those years plus examination of certain specimens as indicated below. These data are not as complete as one might desire, but records were kept of dates of arrival, departure and nesting. I believe that they show the general trend of the population activities. For convenience, the population has been divided into five groups: Permanent residents; regular migrants (those species of which no individuals stopped to nest); summer visitants; winter residents; and those of erratic (irregular) occurrence. It is of importance to point out that the area is entirely within the Upper Sonoran Life-zone; that the area was, as it is now, given over to agriculture, hay and potatoes being the chief products; that no large native trees are in the area; and that the closest mountains are twenty-five miles to the south. The Snake River, with its native riparian growth of willow, bounds the area on the south. For a more extended account of the topography see Kenagy (loc. cit.). Names here employed are those of the A. O. U. Check-list, 4th ed., 1931.