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 THE CONDOR A MAGAZINE OF WESTERN ORNITHOLOGY Volume XV May-June, 1913 Number 3 A STUDY OF THE NESTING OF THE MARSH HAWK By ARETAS A. SAUNDERS WITH SIX PHOTOS BY THE AUTHOR IN THE prairie portion of Teton County, Montana, the Marsh Hawk (Circus hudxoniux) is the most abundant of all the hawks. During the nest- ing season of 1912 I was fortunate in finding a nest of this species so close to town (Chouteau, Montana) that I could make observations upon it almost daily. In the near vicinity of this nest was one of the Short-eared Owl, an owl that is almost equally abundant with the Marsh Hawk in this region. My observations on the nesting of the Short-eared Owl are elsewhere recorded in the pages of THE CONDOR (this issue, page 121). The nesting habits of the two species are in general quite similar, each being the only North American species of its family that nests on the ground. In comparing the two species, however, I found that while the general nesting habits are much alike, in many of the details they are quite dissimilar. The Marsh Hawk arrives in this region usually some time in the month of April, adult males usually being seen a week or two in advance of the females. Courtship evidently begins as soon as the females arrive, and may be witnessed frequently during the latter part of April and early May. I have usually ob- served it along the borders of a stream, where a group of cottonwood trees flank a broad open meadow. The female sits in one of the cottonwood trees and watch- es the performance of her mate. He flies back and forth across the meadow at a height varying from about fifteen to fifty feet above the ground. He first flies upward with much flapping of his wings till he reaches the fifty-foot height, then turns in the air with a curious motion that displays first the white rump and then the white of the wing-linings and underparts, and flaps down again to the fifteen- foot level. Then he turns and rises again, and continues thus, up and down,