326 ANIMAL LIFE IN THE YOSEMITE 



the living tree, now and then whacking off the edge of a bark plate in order 

 better to explore the space underneath. 



Stomachs of two adult birds, obtained at Merced Grove Big Trees on 

 June 10, 1915, and at East Fork of Indian Gallon, June 24, 1915, both 

 held ants, some of which were large carpenter ants. The stomach of one 

 of the young birds from the nest mentioned above contained remains of 

 2 large spiders, a large ant, 2 boring beetles, and a whole fly larva. 



Fig. 42. Feet of (a) Northern WMte-headed Woodpecker, and (Z?) Arctic Three- 

 toed Woodpecker, showing gi'eater size' of latter, perhaps compensating for loss of 

 fourth toe. Natural size. 



Arctic Three-toed Woodpecker. Picoides arcticus (Swainson) 



Field characters. — Size somewhat less than that of Eobin. Upper surface uniformly 

 black save for golden yellow patch on crown of male (pi. 5c) ; middle of under surface 

 white (sometimes stained tan-color) ; flanks, sides of body, and under surface of wings 

 barred narrowly with black and white, and outer surface of wings finely spotted with 

 white. (These characters of barring and spotting were confessedly not apparent to us 

 in the field.) Voice: A low, single-syllabled note, pert, week, or tup. 



Occurrence. — Sparse resident of Canadian and Hudsonian zones on west slope of 

 Sierra Nevada. Observed at head of Grouse Creek, in basin of Bridal Veil Creek near 

 Mono Meadow, at Lake Tenaya, at Tuolumne Meadows, and at 8600 feet altitude near 

 McGee Lake. Forages chiefly in lodgepole pines. 



Like the Great Gray Owl, the Arctic Three-toed Woodpecker is a 

 typically boreal species finding its southern limit of distribution in the 

 central Sierra Nevada, The instances of occurrence cited above are the 

 southernmost now known. 



This woodpecker impressed us as being relatively rare. Only twelve 

 individuals were seen or heard in several months of field work in the 

 Canadian and Hudsonian zone forests. Being a quiet bird it may often 

 have been overlooked, and therefore may be actually much more plentiful 

 than our few records indicate. Attention is usually attracted to the birds 

 by the noise they make when drilling. 



On June 20, 1915, a nest of this woodpecker was discovered in a dead 

 lodgepole pine which stood less than 10 feet from the bank of Bridal 



