118 ANIMAL LIFE IX THE YO SEMITE 



Usually the -wood rats obtained for specimens were trapped close to 

 nests, but in one instance an immature individual was taken in a trap 

 set on the ground beneath chaparral in a place where no evidence of wood 

 rat activity was to be seen. At El Portal there were indications that the 

 wood rats were using the trails made by the brush rabbits through and 

 beneath the greasewood chaparral. These rats have regular paths or trails 

 of their own, especially along the walls of narrow ravines. These paths 

 are kept more or less bare of leaves, evidently by the frequent passage of 

 the animals over them. At Dudley the rail fences through dense chaparral 

 were being used regularly as highways ; the lower rails were chosen rather 

 than the uppermost one, doubtless on the principle of "safety first." At 

 Kinsley, droppings of wood rats were found in the farthest recesses of a 

 cave some 50 feet from its entrance. Animals living there would have to 

 seek territory for foraging altogether outside the cave. 



The most conspicuous feature in the life history of the Streator Wood 

 Rat is its propensity to build houses. These structures are usually conical 

 in shape and measure from 18 inches to 3 feet in height, having the same 

 or a slightly greater diameter at base. A majority of the houses are built 

 on the ground, among or beside brush plants, but seldom far away from 

 such trees as live oaks and willows. Sometimes the nests are placed on 

 horizontal branches in oak trees at heights of as much as 15 feet above the 

 ground. Less often the animals live among the rocks, and then the shape 

 of the house or nest is accommodated to the crevices available between 

 adjacent slabs or boulders. Now and then the structure is heaped around 

 a downed tree, as described below; and in one case a nest was found in 

 the hollow trunk of a living black oak. 



Tlie usual wood rat nest is only a pile of various sorts of material of 

 such kinds as can be accumulated from the near vicinity of the site. Within, 

 there is a nest chamber of varying size and proportions. The houses some- 

 times have underground retreats or passageways, as through a hollow 

 tree root, so that in time of danger the wood rat can escape from the nest 

 without appearing on the surface of the ground until it is some distance 

 away. Entering into the composition of different houses in the Yosemite 

 foothills we found the following materials: twigs and green cuttings of 

 Ccanothus cuncahts, C. intcgcrrimus, buckeye, live oak, golden oak, yellow 

 pine, and willow, reed stalks, cones of yellow pine, chunks of decayed wood, 

 and, in one case, stones, each weighing several ounces. 



On a digger-pine-covered hillside which had been burned over within 

 a year, near the McCarthy ranch, 3 miles east of Coulterville, a house of 

 the Streator Wood Rat was found and studied, June 2, 1915. (See fig. 14.) 

 This structure had been built on and i)ar11y within a rotten log which 

 lay on the ground. There was a that eh of dry sticks and jiieees of bark 



