APPENDIX TO OSCINES. 225 



Lepus ariemis'ia, L. campesiv'is, EretMzon epixantlius, Ardomys flavirenter, aud various 

 species of Sciurus, Spcrmophihis, Tamias, Mephliis, Xeotoma, Blurina, aud the small 

 rodt'utia are commou, all diti'ering from the eastern representatives of the genera, or 

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

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

 alpine form. 



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

 hills, but is seldom found higher than 6,500 feet. A Biifo aud a Baiia are occasionally 

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

 and a large blackish snake (Coluber ?) occur sparingly as high as 9,000 feet. In some 

 fe«- 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 commou, 

 while nineteen were more or less rare, aud 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-one are considered by many ornithologists to be merely geographical 

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

 avi-fannal 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 breediug season seems surprisingly suuill when com- 

 pared with those found 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 aquatic birds, have nearly twice as 

 many. Nor is the paucity of species c()uq)eusated for by the number of individuals. The 

 vast, gloomy forests, the rocky xn'ecipitous mountain sides, the deep ravines aud 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 asjiect of the 

 great plains. It is only in a region whei'e prairies and mountains, woods aud open 

 meadow, and marsh aud lake, are in close proximitj^, that we can look for a great 

 variety of species ; asd where tiie mouutains, the plains, the forests or the prairies, 

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

 more limited. 



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

 lines which divide them, may be seen by a compaiisou 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, oti the other hand, four species were common in 

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

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

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

 main range. The same abrupt transitions may be noticed in the ilora, a snuill ridge 

 limiting the range of species and marking a local tlora. 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 

 ai)]icar to have that decided inlluence which it is generally supposed to exert. The 

 <lilfcrent temperatures, of course, dc[»end ultimately upon it; and plant and animal 

 life are so intimately related to (.'limate that the one can scarcely vary without pro- 

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

 mere altitude, to a degree wholly nnexpect(;d 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 about 1:5,000 feet (Allen), while at the South IJoulder Pass it is several hundred feet 

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

 latter point being not more than thirty or tliirty-liv(! miles north of the former. Ber- 

 thoud's Pass, indeed, is in no place ab(i\c timber-line, though, aceoiding to the saiuo 

 authority, it is 000 feet higher (lO.-IlD), and is less than ten miles south of it. Thus, 

 with a ditference of ;?,0(I0 ieet or more in the altitude of timber-line within so short a 

 <listance, and corresponding modifications in the altitudes of all tin; local Ilora- and 

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

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

 general way. it may b(^ said tiuit near the summit of the peaks and higher portions of 

 the range is an arctic region, eharacterizeil by the Ptarmigan and (Jiay-crowned Finch, 

 and the j)resence of perpetual snow-fields; that bt low this is a sub-arctic belt, in 

 whicli various forms of alpine willows and northern plants llourisb, aud inhabited by 



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