1916] Dice: Land Vertebrates of Southeastern Washington 311 



The growth of timber along the smaller streams of the prairie area 

 does not extend far from the banks of the streams. In most places 

 along the Touchet River trees do not naturally grow more than a 

 quarter of a mile from the stream, and often the width of the habitat 

 is much less than this. As the valley of the Touchet near Fresco tt is 

 nearly a mile broad on the average, it is evident that the growth of 

 trees and brush covers only a portion of the nearly level floor of the 

 valley. 



The most conspicuous plants of the habitat are the cottonwood 

 (Populus trichocarpa) and willows (Salix) of several species. Other 

 trees and shrubs which are common along the banks of the Touchet 

 River near Prescott are the birch (Betula microphylla) , alder (Alnus 

 rhombifolia), chokecherry (Prunus demissa}, thorn (Crataegus brevi- 

 spina) , service-berry (Amelanchier florida), red osier (Cornus stolo- 

 nifera), and syringa (Philadelphus lewisii). Less important species 

 are the cascara sagrada (Rhamnus purshiana), ninebark (Opulaster 

 pauciflorus) , elder (Sambucus glauca), wild cherry (Prunus emar- 

 ginata}, snowberry (Symphoricarpus sp.), and clematis (Clematis 

 ligusticifolia) . Roses (Rosa sp.) occur commonly, especially along the 

 outer margins of the timber. The cottonwood often makes very large 

 trees with a height of 80 to 100 feet and with trunks three to four 

 feet in diameter, but the other trees are much smaller. Under the 

 trees there is nearly always a heavy growth of shrubby underbrush. 

 A growth of shrubs also covers many small areas over which trees 

 have not become dominant. Where the habitat has not been disturbed 

 by man the thick tangle of smaller shrubs, thorns, and vines makes 

 excellent refuges for birds and mammals. 



The cottonwood-willow association is made up of a great number of 

 species. A large number of these are closely restricted to the cotton- 

 wood-willow habitat. A few species which reach their greatest 

 abundance in the cottonwood-willow association are found in lesser 

 abundance in the bunchgrass association. Other species of greatest 

 abundance in the bunchgrass association are sparingly represented 

 in the cottonwood-willow association. Several species of birds nest or 

 obtain shelter in the cottonwood-willow habitat but forage out into 

 the adjacent bunchgrass. 



Sixty traps set in the timber and brush along the Touchet River 

 two miles east of Prescott caught on July 2, 1914, 2 Reithrodontomys 

 megalotis nigrescens, 8 Peromyscus maniculatus gambelii, and 5 Micro- 

 tus nanus canescens. 



