148 



COMMON MURRE (uria aalge; choices 6', 7, 23 and 24, pp. 66, 70-71) and 

 THICK-BILLED MURRE (u. lomvia', choices 6, 7', 23 and 24, pp. 60, 70-71). 

 If the specimen has a head, one should have little difficulty in separating 

 these two species. If it has no head then the task is not as easy. 



Both species breed abundantly from the Bering Straits to western 

 Alaska, and the Common Murre from there to central California. During the 

 non-breeding period, Common Murres occur from ice free Bering Sea waters to 

 northern Baja California. Thick-billed Murres winter as far south as south- 

 east Alaska and regularly but very rarely to central California. Any Thick- 

 billed Murre specimen encountered south of southeast Alaska should be saved 

 for verification. Young murres begin their sea-lives when only a quarter 

 the size of adults. 



BLACK GUILLEMOT (Cepphus grylle; choices 4 and 4', pg. 66) and PIGEON 

 GUILLEMOT (c. oolumba; choices 10 and 10', pg. 69). Wing color is the 

 major character by which these two species can be separated. Size measure- 

 ments can also be useful, as the following table shows (from Storer, R. W., 

 1952) for specimens from the Bering Sea, where the two overlap in distri- 

 bution (measurements in mm): 



BLACK GUILLEMOT PIGEON GUILLEMOT 



Wing 165-175 174-195 



Tarsus 27-34 31-38 



Culmen 27-35 31-37 



The two species occur year round as far north as ice free waters 

 exist. The Black Guillemot does not occur south of the Bering Sea but 

 the Pigeon Guillemot occurs as far south as southern California. During 

 the late fall and winter, Pigeon Guillemots are uncommon in coastal waters 

 south of British Columbia. 



MARBLED MURRELET (Brachyramphus marmoratus; choices 30 and 30', pp. 71-72), 

 KITTLITZ'S MURRELET (B. brevirostris; choices 28 and 28', pg. 71), and 

 ANCIENT MURRELET (SuntiiUbovcmphue antiguum choices 20 and 20', pg. 70). One 

 should have no difficulty in distinguishing these species from one another, 

 or from other murrelets, unless only part of a specimen is available. The 

 following table (based on Sealy, 1972; Jehl and Bond, 1976; Bedard, 1969; 

 and Ridgeway, 1919) may be useful (measurements in mm): 



MURRELETS 

 Marbled Kittlitz's" 7 Ancient Xantus' Craveri 's 



Wing 120-140 127-141 132-149 111-128 107-124 



Tarsus 13.9-17.6 15.5-16.5 24.6-28.0 21.2-27.5 21.0-24.5 

 Exposed 



Culmen 13.2-17.6 9.5-10.5 12.2-15.1 15.6-21.4 18.0-22.5 

 Bill 



Depth 5.3-7.0 5.1 6.4-8.5 6.2-6.5 4.6-5.9 



\f Based on few specimens, range in measurements may be slightly greater; 

 bill depth is an average. 



