NORTHERN WHITE-HEADED WOODPECKER 101 



off; occasionally, one has worked horizontally around a tree trunk, 

 but not downward. Dr. J. C. Merrill (1888) describes its method 

 of feeding very well, as follows : 



So far as T have observed, and during the winter I watched it carefully, its 

 principal supply of food is obtained in the bark, most of the pines having a 

 very rough bark, scaly and deeply fissured. The bird uses its bill as a crowbar 

 rather than as a hammer or chisel, prying off the successive scales and layers 

 of bark in a very characteristic way. This explains the fact of its being such 

 a quiet worker, and as would be expected it is most often seen near the base 

 of the tree where the bark is thickest and roughest. 



It must destroy immense numbers of Scolytidae, whose larvae tunnel the 

 bark so extensively, and of other insects that crawl beneath the scales of bark 

 for shelter during winter. I have several times imitated the work of this 

 bird by prying off the successive layers of bark, and have been astonished at 

 the great numbers of insects, and especially of spiders, so exposed. 



Prof. F. E. L. Beal (1911) examined only 14 stomachs, but says 

 that "half of the animal food of the white-headed woodpecker 

 {Xenopicus albolarvatus) is ants, but the most pronounced character- 

 istic of this bird is its fondness for the seeds of pines, which constitute 

 more than half of the food." 



Grinnell and Storer (1924) say: "Stomachs of two adult birds, ob- 

 tained at Merced Grove Big Trees on June 10, 1915, and at East Fork 

 of Indian Cailon, 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." 



Major Bendire (1895) quotes Eollo H. Beck as saying: "I noticed 

 one of these birds on some fallen logs near the road, busily engaged 

 in catching spiders, searching for grubs, and frequently flying after 

 passing insects, catching them in mid-air in the manner of the 

 California Woodpecker." 



Behavior. — Dr. Merrill (1888) writes: "Though not shy, and with 

 care generally approachable to within a short distance, it is w^atchf ul 

 and suspicious, and seems to know very well what is going on even 

 if it does not see fit to fly away, though it is more apt to do this 

 than to dodge around the trunk. The flight is direct, and rather slow 

 and heavy." Dr. Merrill noted that the skull of the vv-hite-headed 

 woodpecker is "noticeably less hard and dense" than the skulls of 

 other woodpeckers; this is probably due to the fact that its method 

 of feeding requires less heavy drilling into hard wood. 



Mrs. Florence M. Bailey (1902) says: '"''Xenopicus works with ap- 

 parent indifference on trunks or branches. Like the Nuttall wood- 

 pecker he often lights upside down. In hunting over the bark he 

 easily backs down the trunk, or if he takes the notion will fly, or 

 perhaps drop backwards, a foot or so. He will also light sidewise on 

 a branch and grasp the limb with his tail as if afraid of falling off. 



