APPENDIX TO OSCINES. 225 



Lepus ariemisia, L. cnmpesiris, Erethi~on epixanfhvs, Arctomys flavircnier, and various 

 species of Saiiiriis, Sj>e)inophilus, Tamias, •Mephitis, Neotoma, Blariiia, and the small 

 rodeutia are cominon, all differing from the eastern representatives of the genera, or 

 even generically distinct. Above and near timber-line, and occasionally wandering a 

 long way below it, is found the Little Chief Hare, Lagomys princeps, an essentially 

 alpine form. 



Reptiles are rare in the mountains. A species of rattlesnate is common in the foot- 

 hills, but is seldom found higher than 6,50U feet. A Biifo and a Rana are occasionally 

 seen in the valleys of the larger streams as high as Georgetown ; while a Tropidonotus 

 and a large blackish snake {Coluber ^ occur sparingly as high as 9,000 feet. In some 

 few lakes Siredon or Amhlystoma are found. With the lower animals the difference 

 between eastern aud western forms is much greater than it is among the higher. 



Of the one hundred and twenty species of birds I have found here, eighty-three were 

 observed throughout the breeding season ; of these sixty-four were quite common, 

 while nineteen were more or less rare, and but seldom observed. Of the thirty-seven 

 remaining species, twenty-one were common and sixteen rare. Fifty-three species, or 

 nearly one-half, are different from eastern forms and peculiar to the West; but of 

 these, twenty-oue are considered by many ornithologists to be merely geographical 

 races, leavmg thirty-two species characterizing this region as distinct from the eastern 

 avi-faunal provinces. Twenty-two of the breeding species do not rear their young ■ 

 below 7,500 feet, and three, only, above timber-line. 



Taking into account the varied climate, surface, and general features, the number of 

 birds that are common during the breeding season seems surprisingly small when com- 

 pared with those fouud in less diversified regions. Southern Iowa, a rolling prairie 

 country, has at least a number greater by twenty or twenty-five ; and certain portions 

 of the State, embracing the marshy haunts of acjuatio birds, have nearly twice as 

 many. Nor is the paucity of species compensated for by the number of individuals. The 

 vast, gloomy forests, the rocky precipitous mountain sides, the deep ravines and sandy 

 hill-tops scattered with straggling pines, even the broad open valleys are, save on rare 

 occasions, remarkably poor in bird-life. The greatest number of birds is to be found 

 in the parks ; but even these have more or less of the dreary, desolate aspect of the 

 great plains. It is only in a region where prairies and mountains, woods and open 

 meadow, and marsh and lake, are in close proximity, that we can look for a great 

 variety of species ; and where the mountains, the plains, the forests or the prairies, 

 extend alone over great areas, the forms of bird-life, as well as all others, must be 

 more limited. 



The small areas to which the local mountain avi-faunie are confined, and the sharp 

 lines which divide tbem, may be seen by a comparison with the lists of J. A. Allen, who, 

 in 1871, made an exploration of the fauna of the South Park and adjacent mountains. 

 Five species are given as common in that region, which were not observed at all in 

 Clear Creek County, or else so rarely as to leave no doubt that they were mere strag- 

 glers; three or four others were more or less frequent, which in the latter region were 

 scarce or entirely wanting; while, on the other hand, foui' species were common in 

 Clear Creek County, and four or five more or less frequent, that are entirely wanting 

 in Allen's lists, or else given as quite rare. Yet the two regions are contiguous, have 

 nearly the same physical characteristics, and are divided simply by a spur from the 

 main range. The same abrupt transitions may be noticed in the flora, a small ridge 

 limiting the range of species and marking a local flora. The main range — Sierra 

 Madre — of course, is the most important of these dividing lines, but the subsidiary 

 and independent ridges often mark out areas almost as distinctly. Nor does elevation 

 appear to have that decided influence which it is generally supposed to exert. The 

 different temperature^ of course, depend ultimately upon it; and plant aud animal 

 life are so intimately related to climate that the one can scarcely vary without pro- 

 ducing a change in the other. Yet other causes combine to modify the infiuenco of 

 mere altitude, to a degree wholly unexpected by one who has not studied the subject 

 in all its actual aspects. Thus, the limit of the growth, supposed by most persons to 

 be represented by a nearly constant figure, varies so greatly that on Mount Lincoln it 

 is about13,000 feet (Allen), while at the South Boulder Pass it is several hundred feet 

 below the summit of the range, which is given by Prof. Hayden at 10,200 feet, the 

 latter point being not more than thirty or thirty-five miles north of the former. Ber- 

 thoud's Pass, indeed, is in no place above timber-line, though, according to the same 

 authority, it is 600 feet higher (10,800), aud is less than ten, miles south of it. Thus, 

 with a difference of 3,000 feet or more in the altitude of timber-line within so short a 

 distance, and corresponding modifications in the altitudes of all the local florte and 

 fauufe, it will be seen that an attempt to mark out zones of certain elevations, corre- 

 sponding to similar zones as determined by latitude, would be quite futile. Yet, in a 

 general way, it may be said that near the summit of the peaks and higher portions of 

 the range is an arctic region, characterized by the Ptarmigan and Gray-crowned Finch, 

 and the presence of perpetual snow-fields; that below this is a sub-atctic belt, in 

 which various forms of alpine willows and northern plants flourish, and inhabited by 

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