140 



SKUAS cf. SOUTH POLAR SKUA (Catharaota maooomrlcki; choice 1, pg. 50) 

 occurs throughout our area in the summer and fall but is virtually absent 

 at other times. All specimens should be saved. 



POMARINE JAEGER (stercorarius pomarinus; choice 2, pg. 50), because of 

 its large size, might be initially confused with the skua. This species, 

 though, is actually much smaller. They breed in Alaska and winter 



in tropical waters. Occurrence in the Bering Sea and in eastern North 

 Pacific coastal waters is restricted to migratory periods, mainly the 

 fall and less so in spring. 



PARASITIC JAEGER (Stercorarius parasiHous ; choice 3, pg. 50) and 

 LONG-TAILED JAEGER (stercorarius longtoaudus ; choice 3', pg. 50) are not 

 separable on the basis of overall size, a character that will distinguish 

 them from the previous two species. Consult the key and also Willett and 

 Howard (1934) for identification. Occurrence is the same as for the 

 Pomarine Jaeger. The Long-tailed Jaeger is probably more common (relative 

 to other jaegers) in North American coastal waters than presently suspected. 



GULLS (LARIDAE, subfamily LARINAE) 



Gulls are a well-known group of birds. Within their group, however, they 

 can be very difficult to tell apart. Most species have two or three 

 immature plumages which compounds the problem. These immature plumages 

 are sometimes very similar between species; often individual specimens can 

 only be identified by consulting experts, and some specimens even then 

 remain unidentified. Nonetheless, much useful information can be obtained 

 by the identification of the various species and age classes. Wings of 

 badly decomposed specimens or specimens lacking heads can usually be 

 identified by experts and are often worth saving. The only complete 

 reference describing the plumages of gulls is Dwight's 1925 technical 

 monograph of the group. 



GLAUCOUS GULL(Larus hyperboreus; choices 61-63, pg. 61) is a very 

 large, white-primaried gull common only in Alaska. Small numbers can be 

 found as far south as the California-Mexico border in winter. Most birds 

 south of Canada are immatures. Caution must be exercised in dealing with 

 individuals of other species that are albinistic or have very worn 

 feathers. Glaucous Gulls are rarely pure white. Some individuals may 

 appear pure white but most immatures will show buffy marbling at the base 

 of the central tail feathers and adults show a pale gray mantle. 



