26 



GULLS AND TERNS 



Fig. 44. Wing of Franklin Gull. 



with subterminal band of dusky ; rest (/ 

 tail, under parts, forehead, and eyelids- 

 white. Length: 13.50-15.00, wing 11.25 

 bill 1.30, tarsus 1.60. 



Distribution. Interior of North 

 America, breeding 1 from Iowa north into 

 Canada ; migrating south to Peru. 



Nest. On broken-down rushes in shal- 

 low water, made largely of grasses and 

 rushes. Eggs : usually 3. 



In the northern plains and prairie country Franklin gulls are of 

 the greatest economic importance, the immense flocks living mainly 

 on grasshoppers and other destructive insects. At times a white 

 horde will descend upon a ploughed field, a band of them following 

 at the heels of the ploughman, while long white lines cover the 

 mellow furrows. Recognizing the ploughman as a friend, the birds 

 only get out of his way to let him pass, waiting for him to turn up 

 a fresh supply of food for them. They walk in the furrows or 

 hover low over the ground, diving quickly to pick up any squirm- 

 ing morsel, either insect or rodent, that has been unearthed by the 

 plow. One often sees flocks of fifty to five hundred catching grass- 

 hoppers on the wing, wheeling, diving, and rising, till at a distance 

 the white flock suggests a wild flurry of snowflakes. When the 

 meal is over the birds disband, to scatter out among the sloughs, 

 drift on lazy wings over the lakes, or float idly on the surface of the 

 water. VERNON BAILEY. 



60. Larus Philadelphia (Ord). BONAPARTE GULL. 



Adults in summer. Bill and head black ; mantle delicate pearl gray ; 

 three outer quills chiefly white, outer 

 web of the first, and terminal portion of 

 all, black ; tail and under parts white ; 

 feet orange red. Adults in winter : head 

 white, tinged with gray behind and with 

 a dusky spot on ear coverts ; feet pale 

 flesh color. Young : top of head, back, 

 and spot on ear coverts dusky ; sides of 

 head, neck, and under parts white, in- 

 cluding tail coverts and base of tail; 

 Length : 12- 



Fig. 45. 



band across end of tail blackish, feathers tipped with white. 

 14. wing 10.25, bill 1.20. 



Distribution. North America, breeding far northward ; south to western 

 Mexico. 



Mr. Henshaw states that the Bonaparte gull is not uncommon in 

 San Diego Bay in December, though he thinks it winters mainly to 

 the southward. 



Mr. Looinis has seen the gulls at Monterey during their migrations 

 in November and May. He says that "although white-throated 

 birds with the tail-band were in the majority, and pied-headed ones 



