156 THE CONDOR VOL. X tract lying south of the Grand River and west of the Gunnison, and as the Dolores forms a natural highway for southern forms to wander into the County, it is not unreasonable to suppose that a number of species occur with more or less regular- ity in the southern end of the County, which have not yet been observed or recorded. Partly on this account and partly on account of the unavoidable incomplete- hess of this list, the writer has included in the body of the list, but in brackets and smaller type, those species whose established range undoubtedly includes Mesa County, and whose seasonal movements make their occurrence within the county boundaries a practical certainty at some time of the year. The authority for in- cluding these hypothetical species in the list is derived from the ranges given in Prof. W. W. Cooke's l?irds of Colorado, and the list of these species has been further passed upon by him, with particular reference to Mesa County. This feature of the list has been included simply as a guide in field work and as an aid LEON PEAK, THE HIGItEST POINT IN MESA COUNTY, 10,954 FEET ALTITUDE to intelligent efforts in clearing up the many points of uncertainty regarding Mesa County Ornithology. The entire list as it stands includes 203 species, 159 of which have been defin- itely recorded for Mesa County, while the remaining 44 species altho not having been found within the County boundaries up to the present time, will probably be reported from there in the future. ANNOTATED LIST [?[?chmophorus occidentalis. Western Grebe. This western species is an abundant summer resident in Utah and has been seen in South Park by Carter, so probably occurs regu- larly in Mesa County during migration, tho never in any abundance.] Colymbus nigricollis californicus. American Fared Grebe. Summer resident, not common. This species is undoubtedly a regular migrant, but the writer has only seen it once. Mr. Floyd Sinalley reports it as a regular summer resident at a small reservoir in Plateau Valley at about 6500.
