654 



BULLETIN 50^ UNITED STATES NATIONAL MUSEUM. 



BLASIPUS HEERMANNI vCassin). 



HEERMANN'S GULL. 



Adults in summer (sexes alike). — Head and upper neck, all round, 

 immaculate white, deepening gradually into light mouse gray on lower 

 neck and under parts and into grayish brown (nearly quaker drab) 

 on back, scapulars, wing-coverts, tertials, and rump, the tertials 

 passing into white at tips; secondaries darker grayish brown, broadly 

 tipped with white; primaries dull black, the proximal ones narrowly 

 tipped with white; under surface of wings uniform grayish brown, 

 like upper surface; upper tail-coverts hght gray; tail dull black, tipped 

 with white; bill bright red, sometimes tipped with black; iris grayish 

 brown or brownish gray ; naked orbital ring red ; legs and feet black. 



Adults in winter. — Similar to summer adults, but head and upper 

 neck dusky grajdsh brown instead of white. 



Young. — Entirel}^ sooty grayish brown, lighter and more grayish 

 on under parts; wing-coverts, scapulars, feathers of rump, and upper 

 tail-coverts margined terminally with grayish white; tail blackish 

 dusky very narrowly tipped with white; bill brownish, the terminal 

 tliird black; legs and feet brownish black. 



Immature (first winter) ? — Similar to young in fh-st plumage (as 

 described above), but without pale margins to wing-coverts, etc., the 

 general color rather darker, the tail without white tip ; bill Hght red- 

 dish for basal two-thirds, the terminal portion black; legs and feet 

 brownish black. 



^(Z-uZ^waZe.— Wing, 344-376 (360.4); tail, 131-154 (139.6); exposed 

 culmen, 42-48 (45.7); tarsus, 48.5-54 (52.2); middle toe, 44-51 

 (47.9).« 



Adult female.— Wing, 338-356 (346.2): tail, 132-162 (137.2); ex- 

 posed culmen, 39.5-43.5 (41.7) ; tarsus, 47.5-51 (49) ; middle toe, 42.5- 

 46.5 (44.9).« 



a Ten specimens. An adult female from Washington (Gl•an^^ille, July 10), the only 

 specimen examined from any locality north of San Fi'ancisco, is larger than others, 

 its measurements being as follows: 



LocaUt: 



■^^■in2 



Tail. 



Ex- 

 posed 

 cul- 

 men. 



Tarsus. 



Middle 

 toe. 



One adult female from Washington C'Jranville, July 10) ."SG 



Six adult females from California (Aptos, July) 343. 5 



Two adult females from ESpiritu Santos Island, Lower Cali- 

 fornia ( February) i 350. 5 



One adult female from Todos Santos Island, Lower California 



(May 21) 342 



162 42 



134.5 4L 



132.7 

 135 , 



40.2 

 43 



51 

 4a 6 



49 

 49.5 



46.5 

 45 



44.2 



44 



