29 



KEY TO PETRELS (Cont.) 



12 Bill large and thick, nasal tube prominent, about 40% of bill 

 length (Plate 5); lower mandible not decidedly hooked at tip; 

 body stocky; tarsus rounded in cross-section. 13 



12' Bill slender (especially when viewed from above), nasal tube 

 about 25% of bill length (Plate 6); lower mandible hooked; body 

 slender, torpedo-shaped; tarsus flattened laterally when viewed 

 in cross-section. 15 



13 Underparts of body white. 14 



13' Underparts of body light gray to dark brown. 



NORTHERN FULMAR, dark phase 



14 Crown, nape and hind neck light gray; underside of head and neck 



white. NORTHERN FULMAR, intermediate phase 



14' Head and neck white. NORTHERN FULMAR, light phase 



15 Belly white or partly white. 16 

 15' Bird entirely dark, except bill and feet may not be dark. 19 



16 Wing length 270-300 mm; tail decidedly wedge-shaped; under tail 

 coverts white; inner webs of primaries largely white; in fresh 

 plumage, back light to medium gray; a prominent dark "W" pattern 

 visible when both wings are extended (not evident in worn plumage). 



BULLER'S SHEARWATER 



16' Wing <270 mm OR greater than 300 mm; tail not decidedly wedge- 

 shaped; under tail coverts dark; inner webs of primaries dark; 

 back brown, never a "W" pattern over wings and mantle. 17 



17 Wing <270 mm; bill black along top and at tip, remainder bluish- 

 gray; legs and feet light (flesh-colored) but with outer side of 

 tarsus and outer toe black. 



COMMON SHEARWATER (See Species Accounts) 



17' Wing >300 mm; bill largely straw-colored except darker along top 



and at tip; legs and feet entirely light (flesh-colored) but tending 

 toward brown along outer toe. 18 



