458 Colorado College Publication 



The following birds are practically restricted to the zone 

 in the breeding season: 



Woodhouse's Jay, Bullock's Ori-ole, Caiion Towhee, West- 

 ern Blue Grosbeak, Lazuli Bunting, Long-tailed Chat, Western 

 Mockingbird, Catbird, Brown Thrasher, Baird's Wren, and 

 Western Gnatcatcher. The following species breed especially 

 in the cedar and pinon trees : Ash-throated Flycatcher, Pinon 

 Jay, Black-throated Gray Warbler, Gray Titmouse, and Lead- 

 colored Bush-Tit. 



The following trees and shrubs are characteristic of the 

 Upper Sonoran Zone : 



Piiion Pine, Pinus edulis, two species of cedar, Juniperus 

 scopulorum and /, monosperma, Broad-leaved Cottonwood, 

 Populus occidentalis, Peach-leaf or Almond-leaf Willow, Salix 

 auiygdaloides, Gray Saltbush or Bushy Atriplex, A. canescens, 

 Western Clematis, C. ligusticifoUa, Flowering Currant, Ribes 

 iongifoHuin, Wild Plum, Primus americana, while six species 

 of scrub oaks are found in this and the lower part of the Tran- 

 sition Zone. 



TRANSITION ZONE. 



The Transition Zone covers the greater portion of the 

 foothills and the lower parts of the mountains' proper, and the 

 Divide region in the northern portion of the County. The 

 former are naturally more or less rough, and the latter is an 

 undulating country. The upper limit of the Transition in El 

 Paso County varies from 8,000 to 9,000 feet, changing with 

 the slope exposures. The cedars and pihons seemingly overlap 

 into this zone from the zone below, and there are some places 

 where it is difficult to decide to which zpne that locality 

 belongs. 



In this County there is but one mammal which can be 

 said to be restricted to. this zone, the Northern Tuft-eared or 

 Plain-backed Squirrel, Sciunts aberti ferreus, though the 

 Plains or Coues's Pocket Gopher, Thoinoinys clusius, Estes 



