CHIPMUNKS ' 179 



have census figures to offer, they are not so definitely dependable and 

 show greater discrepancies than do those for most birds. At Porcupine 

 Flat on June 28, 1915, four Tahoe Chipmunks were noted during a single 

 hour, while on two other occasions, once at the same locality and again 

 near Mono Meadow, seven of these animals w^ere recorded during five hours 

 of active observation. It is our impression, gained from extensive field 

 experience, that the Tahoe Chipmunk has its maximum of abundance in 

 the Canadian Zone on the west slope of the Sierras. Again calculating 

 largely from impressions, we would set down the spring population of 

 the Tahoe Chipmunk, before emergence of the young-of-the-season, as 

 about two an acre or 1280 a square mile through the forested portions 

 of the Canadian Zone. In the tree-covered portions of the Hudsonian Zone 

 the population is only about one-half as great. In the late summer when 

 the young are out and all ages are represented, the impression of 'swarms' 

 of chipmunks is given, especially in those localities where forage conditions 

 are most favorable. 



The Tahoe Chipmunk shows greater latitude in the matter of its local 

 range than does any of the other Yosemite cliipmunks. It runs around a 

 great deal on the ground and over fallen logs, and at times it climbs the 

 brush plants to harvest the crops of seeds or fruit. But the most notable 

 feature in the behavior of the species is its tree-climbing propensity. It 

 habitually goes up into trees at the first hint of danger, climbing many feet 

 above the ground. Even when not frightened the animals do much running 

 around in trees. Frater is an adept climber and can go rapidly up the 

 side of a perpendicular trunk, even up such smooth-barked trees as young 

 lodgepole pines and firs. When a frightened animal has gained what it 

 considers a safe height above the ground, it will usually lie quietly on the 

 top of a horizontal branch and peer over the side and down at the scene 

 of its late scare. Its brown and streaked coloration matches so well the 

 various shades of color of the trunk and branches that the animal 's location 

 might easily be overlooked were it not for the plume-like tail which often 

 hangs down to one side of the branch, waving back and forth with seeming 

 carelessness. 



Tahoe Chipmunks are able to run down comparatively smooth-barked 

 trees head foremost with ease and safety, either at great speed, or moving 

 slowly a few steps at a time. This bespeaks great efficiency in the structure 

 and use of the claws and toes. Individuals have been seen to leap short 

 distances from one branch to another; but, in this respect, the ability of 

 even this most arboreal of our chipmunks is inferior to that of the Gray 

 and Red squirrels. 



At Walker Lake one day in September one of our party was walking 

 past a smaU Jeffrey pine when a Tahoe Chipmunk suddenly dropped to 



