KEY TO THE WATER BIRDS OF FLORIDA. I9I 



Family LARID.E. Gulls and Terns. 



Subfa:\iily LARIN^. Gulls. 



Genus LARUS Linn. 



LARUS MARIN US Linji. 

 Great Black=backed QuII. 



Adult in sumnier : Whole back dark slate color ; outer primaries black, with tips and termi- 

 nal spots of white : head and under parts white. 



Adult in winter : Head and neck streaked with gray. Immature birds are mottled dusky and 

 buff; head and neck streaked; tail with narrow subterminal band ; a very large gull. 



Length, 29; Wing, 18; Tail, 8: Tarsus, 2.70; Bill, 2.40. 



Coast of North America south to South Carolina; accidental in Florida. 

 Breeds from Northern Maine northward. The nest is built on the ground ; 

 the eggs are usually two, pale brown, marked with chocolate brown. 



A specimen of this gull was shot near St. Augustine during the winter 

 of 1894-5. 



