GULLS AND TERNS 



19 



of head, including ear coverts, 

 straw yellow, paler on throat; 

 chest, and sometimes breast and 

 belly, white, shading- into gray on 

 sides ; under tail coverts, and 

 usually belly, gray ; feet black ; 

 tarsus light bluish. Length : 20- 

 2o, wing- 12.25, bill 1.19, longest 

 tail feathers 10.50-14.50. 



Distribution. Northern part 

 of northern hemisphere, breed- 

 ing in arctic regions ; south in 

 winter to Florida, Gulf of Mex- 

 ico, and California. Taken at 

 Monterey Bay by Mr. Loomis. 



Eggs. Deposited in a depres- 

 sion in the mossy top of a knoll. 



Fig. 39. Long-tailed Jaeger. 



Fig. 40. 



The long-tailed jaeger is so swift and graceful on the wing that 

 Mr. Nelson compares its flight to that of the swallow-tailed kite. 

 After chasing each other about or pursuing hapless gulls or terns, 

 the birds may often be seen sunning themselves on an elevation, 

 their white breasts pointing them out at a long distance. 



FAMILY LARIDJE. GULLS AND TERNS. 



KEY TO GENERA. 



1. Bill deeper through angle of lower mandible than 

 through nostril. 



2. Hind toe wanting, or a mere rudiment. 



Rissa, p. 19. 

 2'. Hind toe small but perfect. 



3. Tail square across end .... Larus, p. 20. 



3'. Tail deeply forked Xema, p. 27. 



1'. Bill deeper through middle of nostril than through 

 4 angle of lower mandible. 



2. Tail forked for more than one fifth its length (ex- 

 cept sometimes in S. caspia); outer feathers nar- 

 row and pointed. 

 3. Length of bill less than three times its depth at 



base Gelochelidon, p. 27. 



3'. Length of bill more than three times its depth 



at base . Sterna, p. 27. 



2'. Tail forked for about one fifth its total length, 

 outer feathers wide and rounded at tips. 



Hydrochelidon, p. 31. 



GENUS RISSA. 



40a. Rissa tridactyla pollicaris Eidgw. PACIFIC KITTIWAKE. 



Appearance gull-like ; hind toe minute, with or without a nail ; feet 



Fig. 41. 



