516 U.S. NATIONAL MUSEUM BULLETIN 237 part i 



and throats held seeds appropriate to the area of collecting: Engel- 

 mann spruce, ponderosa pine, and Chihuahua pine." 



Mrs. Amelia S. Allen (1920) observed some of these crossbills 

 feeding on fallen almonds in an orchard; they "picked the almonds 

 from the ground, flew up into the trees and noisily pried open the 

 shells with their bUls. After eating the kernels they dropped to the 

 ground again to search for more." 



Tracy I. Storer (1921) saw some crossbills feeding on the leaves of 

 a cork elm tree: "They were attacking certain of the leaves which 

 were curled up on one edge, cutting these rolls open and getting some- 

 thing from within." On close examination, "it became evident that 

 a woolly aphis, which had caused the curling of the leaf margin was 

 the item of food being sought by the CrossbUls. The attack of this 

 insect causes the blade of the leaf to curl over, forming a cylindrical 

 roll within which the aphis can feed and multiply unmolested by most 

 of their enemies. 



"Further watching of the Crossbills showed that the birds had 

 learned the haunt of these particular aphids and also a method for 

 obtaining them. The roll-like cases were cut open lengthwise, but 

 in rather irregular fashion, as well as could be expected of a species 

 with such an unhandy pair of 'scissors'; then the tongue would be 

 inserted and the aphids withdrawn." 



P. A. Taverner (1922) explains how the crossbills open leaf galls as 

 follows : "The bird would open its bill and drive both points deeply into 

 the soft mass of the gall until the mandibles were practically closed 

 and crossed. Then, with a slight twist of the head, the gall would 

 be split wide open. The hollow interior was seen to be filled with 

 what appeared to be a sort of woolly aphis, which was rapidly cleaned 

 out with the bird's tongue. The certainty, ease and rapidity with 

 which the operation was performed indicated that the apparently 

 awkwardly crossed bUl was a most efficient implement for the work." 

 This operation was closely observed on a captive crossbUl that was 

 partially fed on poplar galls. 



Grinnell, Dixon, and Linsdale (1930) saw some crossbills apparently 

 feeding on the green cones of hemlocks, but "examination, later, of 

 the contents of the stomach of the bird taken proved that the only 

 food was a smooth, bright-green caterpillar. Thirteen of these cater- 

 pillars, uniform in size, 12 to 17 millimeters in length, were found in 

 the one bird." 



The fondness of crossbills for salt or salty substances has been 

 noted by several observers. Wherever salty dish water has been 

 spUled, or where salt has been sprinkled on the ground, the birds will 

 alight and lap it up with avidity, turning the head to one side and 

 extending the tongue. 



