May, 1914 BIRDS OF NORTHERN MONTANA 143 mountains in late August and early September. Rare on the prairies, where I observed it near Choteau, May 25, 1912. l?enthestes atricapillus septentrionalis. Long-tailed Chickadee. Common permanent resident of willow thickets in the prairie region, and in the lower mountain canyons up to 5000 feet. Penthestes gainbell gainbell. Mountain Chickadee. Cramnon permanent resident of pine and fir forests in the mountains. Penthestes hudsonicus hudsonicus. HudsonJan Chickadee. Probably a rare permanent resident of spruce forests in the mountains. I observed it but once, when I found a pair, accompanied by six nearly full-grown young, in a dense spruce thicket on the South Fork of the Teton River, at an altitude of 6000 feet. Regulus satrapa olivaceus. Western Golden-crowned Kinglet. Common summer resident of spruce forests in the mountains. Regulus calendula calendula? Ruby-cro?vned Kinglet. Common ?,?. summer resident of fir forests in ?-? . the mountains. Migrant in wil- low thickets in the prairies, where , ? .? I observed it, near Choteau, May ? [- 25, 1912. Myadestes townsendi. To?vn- send Solitaire. Common summer resident about steep cliffs and rocky ridges in the mountains. .,? Hylocichla fuscescens salici- cola. Willow Thrush. Summer resident of willow thickets in the prairies. Most abundant along the foothills in the mountains. Common in Le?vis 'and Clark County, but becoming rare north- ward in Teton County. Itylocichla ustulata swainsoul. Fig. 48. N?s? s?o ?HRr? r?C,S Or Brsc?- Olive-backed Thrush. Abundant ItEADED GROSREAK, ?WITIt OXE EGG OF THE CO?'RIRD. summer resident in the moun- tains, and abundant migrant in cottonwood groves on the prairies. Migra- tion dates: May 22, 1912, August 21, 1911, and September 4, 1912. The latter two dates are from the mountains about the headwaters of the Sun River. Hylocichla guttata auduboni. Audubon Hermit Thrush. Rare migrant. I observed it near Choteau, May 18 and 23, 1912. and on the West Fork of the Sun River, September 12, 1912. Have not observed it here in summer in the mountains, as I have in southern Montana. Planesticus migratorius propinquus. Western Robin. Abundant sum- mer resident in cottonwood groves in the prairies, and in pine and fir forests in the mountains up to 5500 feet. Migration dates: March 28, 1912, and Octo- ber 29, 1911. Begins nesting in the latter part of May. The eggs take about fourteen days to hatch, and the young leave the nest in about ten or eleven days more, so that young are seen on the wing by the middle of June. The
