378 OKNIXnOLOGY. 



former, down to the very verge of the desert, and the presence of so many 

 eastern Ijirds on the Wahsatch and other extreme western ranges of the huter 

 system. It is, therefore, evident that not the mountains, but the deserts, 

 check the species in their range away from their centers of distribution. 

 Jt was also noticed that the species having a general range throughout 

 the Interior were those particularly characteristic of, if not peculiar to, 

 the Basin Province, and that their distribution was regulated less by mere 

 to])ographical features than by other local conditions, the presence or 

 absence of water and vegetation being the main agents. 



As stated in the chapter on the local avifaunae of the Great Basin 

 (see pp. al()-328), certain groups of birds not only characterize particular 

 zones of vegetation, but, also, isolated spots of a particular description, no 

 matter at what altitude. An excellent example in illustration of this case is 

 afforded by the humming-birds of the Interior, which are found wherever 

 flowers grow in profusion, either in the valleys or on the mountains ; they 

 abound most on the upper slopes of the canons, where numerous flowering 

 plants bloom in such abundance as to foi-m natural gardens; but on one day, 

 in August, we observed an individual of Selasphorus platuccrcus in the door- 

 yard of a ranche, in Ruby Valley, the altitude of which was between 6,000 

 and 7,000 feet, while a few hours later, as we stood on the summit of one of 

 the lofty peaks of the East Humboldt range, at an elevation of about 12,000 

 feet above sea-level, and far above the fields of perpetual snow, an individual 

 of the same species flew rapidly by, bound for the slopes of an adjoining 

 canon. The extreme vertical range of this species was thus shown to be 

 nearly 6,000 feet, or more than one mile! In all cases where farms had 

 been established in the valleys, hunnning-birds were noticed in the door- 

 yards, though had not careful cultivation, with the aid of artificial irrigation, 

 produced these oases in the desert, it is needless to say these Ijirds would not 

 have been seen there. Otlicr cases in point are those of the birds frequenting 

 the canon shrubbery, which have a vertical range almost equal to that of 

 the humming-birds, the same species following the streams from the valleys 

 up to the snow-fields, provided the slu-ubbery continues so far. Certain 

 birds which frequent woods, of whatsoever kind, arc almost sure to be 

 found wherever ti-ees occur ; thus Colaptes viexicanm or Picas haniai may 



