142 THE CONDOR Vol. XVI Oporornis tolmiei. MacGillivray Warbler. Common summer resident of willow and wild-rose thickets in the foothills and lower mountains, up to 5000 feet. Occurs in the prairies in migrations. Migration date: May 23, 1912. Geothlypis triohas occidentalis. Western Yellowthroat. Common sum- mer resident of the prairie region and foothills, usually in willow thickets. On the prairies ! have also heard the birds singing in She rushes on the borders of Sloughs, and believe that they nest there. Migration date: May 19, 1912. Wilsonia pusilla pileolata. Pileolated WarbLer. Common summer resi- dent of willow thickets in the mountains, from the foothills to 6000 feet. Com- mon migrant in the prairie region. Observed in .migration at Choteau, May 22-28, 1912, and on the Sun River August 26-28, 1911. Setophaga ruticilla. Redstart. Summer resident of 'the willow thickets along the foothills and in the lower mountain canyons up to 5500 feet. Much more common as a migrant, when it 'also occurs in the prairie region. Ob- served in migration at Choteau, May 22-28, 1912. Anthus rubescens. Pipit. Migrant in the prairie region. Occurs in large flocks with horned larks and ]?cCown Longspurs, and feeds about the borders of alkaline ponds. Migration dates: September 17 to October 1, 1911. Anthus spraguei. Sprague Pipit. Common summer resident of the prai- ries. Appears to prefer neither the dry prairie benches, nor the rich grass meadows, but occurs about the borders of ponds, or in hollow depressions in the prairie where the soil is moist,. but too alkaline to be clothed with a tall thi?k growth of grasses. The bird itself is very difficult to see and observe, but the song is one of the commonest sounds on certain parts of the prairies in June and July. Migration date: May 23, 1912. Cinc!us mexicanus unicolor. Dipper. Permanent resident on mountain streams. Occurs in the vicinity of waterfalls in summer, but winters in places where the fall of the stream is not so steep, and yet where the current is swift enough to keep open water all winter. Begins nesting late in May. Dumetella carolinensis. Catbird. Common summer resident in willow thickets on the prairies, and, along the foothills of the mountains, in thickets of wild-rose. Migration date: May. 23, 1912. Salpinctes obsoletus obsoletus. Rock Wren. Summer resident. Occurs in rocks about the edges of prairie buttes, and in the lower mountain canyons up to 5000 feet. Rather rare. Migration date: May 27, 1912. Trog!odytes aedon parkmani. Western House Wren. Common summer resident of the prairies, nesting about buildings and in dead stumps in cotton- wood groves. Migration date: May 19, 1912. Nannus hiema!is pacificus. Western Winter Wren. Rare summer resi- dent of spruce forests in the mountains. A pair, with brood of young, were observed on Beaver Creek, in the Sun River country, on June 29, 1911. A sin- gle bird observed on Birch Creek, May 31, 1912. Certhia familiaris montana. Rocky Mountain Creeper. Occurs rarely in spruce forests in the mountains. All my records are from about the head- waters of the Sun River, and are between August 29 and September 81 so I am doubtful if the species is more than a migrant here. Sitta carolinensis nelsoni. Rocky Mountain Nuthatch. Summer resident in the mountains. Occurs in Lodgepole Pine and Douglas Fir forests in the Canadian zone, and in White-bark Pine forests in the HudsonJan zone. Sitta canadensis. Red-breasted Nuthatch. Migrant. Common in the
