In Washington pikas live only in talus slides and rock piles, where they find refuge from most of the carnivores that prey on small mammals. Their distribution in the state seems to be regulated by the distribution of talus slides, and areas free of talus act as effective barriers to pikas. They are abundant throughout the Cascades but are absent from the Olympic Mountains although conditions there are well suited to them. Probably the lowlands of western Washington which, owing to moderate temperature and low relief, have little talus and exposed rock, serve as a barrier. The Columbian Plateau is also free of pikas. This may be due to the relative scarcity of talus as compared with mountainous areas, and the fact that much of the talus on the Plateau is composed of fragments of basalt too small to afford the shelter needed by pikas. The aridity of the Columbian Plateau may contribute to the absence of pikas, although this seems unlikely in view of the fact that they occur on arid lands in Nevada and elsewhere. Altitudinally, pikas range from 300 feet, in Clark County, to 6,000 feet on Mt. Rainier, Pierce County, and on Round Top Mountain, Pend Oreille County. They occur from the arid subdivision of the Transition Life-zone, at Milk Creek, Kittitas County, to the upper edge of the Hudsonian Life-zone, at Glacier Basin, Mt. Rainier. Generally speaking, they are mammals of the mountains. Common enemies of the pikas are the weasel (_Mustela frenata_), marten (_Martes caurina_), and hawks of several species. Pikas are active by day, especially in the early morning. Their call note is a short "eek!" which carries a long distance. This squeaking note is often heard throughout the night when rain threatens their drying hay. [Illustration: FIG. 126. Distribution of the pika in Washington. A. _Ochotona princeps brunnescens._ B. _Ochotona princeps fenisex._ C. _Ochotona princeps cuppes._]