733a. =Gray titmouse.= PARUS INORNATUS GRISEUS. Resident; not common; southern species, coming to eastern foothills.
735a. =Long-tailed chickadee.= PARUS ATRICAPILLUS SEPTENTRIONALIS. Not uncommon resident; winters on plains and in foothills; breeds from 7,000 to 10,000 feet; sometimes on plains.
738. =Mountain chickadee.= PARUS GAMBELI. Abundant resident; nests from 8,000 feet to timber-line; ranges in the fall to the tops of the loftiest peaks.
744. =Lead-colored bush-tit.= PSALTRIPARUS PLUMBEUS. Resident; not common; western species, coming to eastern foothills.
748. =Golden-crowned kinglet.= REGULUS SATRAPA. Rare summer resident; rather common in migration; breeds only near timber-line at about 11,000.
749. =Ruby-crowned kinglet.= REGULUS CALENDULA. Abundant summer resident; breeds from 9,000 feet to timber-line.
751. =Blue-gray gnatcatcher.= POLIOPTILA CÆRULEA. Rare summer resident; breeds on the plains and in the foothills.
754. =Townsend's solitaire.= MYADESTES TOWNSENDII. Common resident; breeds from 8,000 to 12,000 feet; winters in mountains, though stragglers are sometimes seen on the plains. The author saw a pair on plains near Arvada, in company with a young, well-fledged bird.
756a. =Willow thrush.= HYLOCICHLA FUSCESCENS SALICICOLA. Summer resident; rather common; breeds in foothills and parks up to about 8,000 feet.
758a. =Olive-backed thrush.= HYLOCICHLA USTULATA SWAINSONII. Rare migrant.
758c. =Alma's thrush.= HYLOCICHLA USTULATA ALAMÆ. Rare summer resident; in migration common.
759. =Dwarf hermit thrush.= HYLOCICHLA AONALASCHKÆ. Rare migrant.
759a. =Audubon's hermit thrush.= HYLOCICHLA AONALASCHKÆ AUDUBONI. Common summer resident; breeds from 8,000 feet to timber-line.
759b. =Hermit thrush.= HYLOCICHLA AONALASCHKÆ PALLASII. Rare migrant; comes to the eastern edge of Colorado, just touching range of _auduboni_.
761. =American robin.= MERULA MIGRATORIA. Summer resident, but not common; some interesting questions arise in connection with intermediate forms.
761a. =Western robin.= MERULA MIGRATORIA PROPINQUA. Abundant summer resident; breeds from plains to timber-line.
765a. =Greenland wheatear.= SAXICOLA OENANTHE LEUCORHOA. European species; a straggler taken at Boulder by Minot.