Phoenix Island/Tahitian Petrel (5) 
Since these two species cannot be satisfactorily separated in the 
field, all sightings must remain referrable to either species, 
1 
Closeness of the breeding grounds and a greater number of collected 
specimens of Phoenix Island Petrels indicate that this speoies is 
the more abundant one in the area. 
Black-winged Petrel (37) 
• * 
This form is common in the grid from July through December and ab¬ 
sent from January through May, Small numbers utilize the grid as 
a "wintering’ 1 area, with greater numbers passing through northward 
t- 
in July, Sightings are invariably of single birds. The majority 
of 34 birds recorded only to Pterodroma speoies during the present 
f 
4 
cruise are probably referrable to this species* but easy confusion 
is possible between this and Cook ! s and White-winged Petrels# 
White-winged Petrel (5+1 nocturnal) 
Birds of this species presently utilizing the grid area belong to 
# 
the race P»l. brevipes , an exceedingly variable form in regards 
to amount of melanism present in individual birds. This race was 
found to be more abundant northwest of the grid area and largely 
• • 
replaced the Black-winged Petrel in that area. The grid appears 
to be within the eastward limits of its wintering range. A lighter 
» ♦ t t 
t 
race, either P«i» leucoptera or P.1, masafuerae , has also beei.- 
collected inthe grid. 
