69 
Bonin (island) (P. h. hypoleuca ) -- Probably the most easily recog¬ 
nisable of the lot but hardly to be expected in the southern areas. Pre¬ 
vious sight records south of the 5“12° N. desert may be misidentification 
In 10 months (July 66 to April 67 ) I have no record for SIC trips at all. 
Birds from the Leeward Island breeding locations may move off to the south¬ 
o • 
west, west, or north. 
Black-winged Petrel (p. hypoleuca nigrinennis ) — In the area around 
Samoa, and in general around the southern areas. This is probably the 
most regular small Pterodroma . From midsummer (August) to late fall 
(November) many birds are found in the 5° and 12° N. belts, probably peak¬ 
ing in the 12° N. area around September-October. 
t 
t 
Pterodroma leucontera . Much commoner than previously thought. From 
September through January may outnumber black-wings in the northern 
waters. Apparently birds come and go to the west, not passing through the 
southern part of the POBSP study area. Their movement may be more clear- 
cut than theblack-wings, appearing and retreating fairly rapidly. The 
• light forms are commoner than the gray-below forms:. The gray birds 
appear smaller than the light birds. In January white-wings were thought 
to'be the major small Pterodroma in the 5° N. area. This is based in part 
on the good number of nocturnal sightings on lk-15 January. Birds then 
were readily attracted to the ship's lights and followed alongside briefly, 
hovering 50-75 feet above the water, occasionally giving a high-pitched 
call note. Collections in November around 5° Nj l 80 °W.showed this species 
to be the dominant form of small Pterodroma . 
*k. 
Pterodroma cooki . Southwestern Pacific birds appear to move east and 
north then west and south during the annual cycle. Birds might appear in 
any of the perimeter areas, but almost certainly do not cross the central 
Pacific area in numbers. Observations in the east and north corroborate 
this hypothesis. 
Pterodroma longirostris . I have no direct information on this bird which 
supposedly is to be expected in the northwest central Pacific area. Un¬ 
fortunately there have been few collections made in the questionaole area 
and this bird may in fact be regular or even common. Its presence may ex¬ 
plain some of the identification problems that exist. 
Identification of the cookilaria is very difficult. I do not, per¬ 
sonally, rely on the back pattern or trust identifications made by this 
criterion alone. The underwing pattern I think may be of most field use, 
but it has gone neglected partly due to "Field Guide" type -descriptions 
based on study skins of specimens with pressed wings. 
Bulwer Petrel $ Obs. - 18 
Bulweria bulwerii See Graphs 103 & 7C 
Birds were regular in low numbers (2 to 5 per <iay) between Starbuck 
and Samoa in April. No birds were seen southwest of the transition zone 
between Phoenix and Fiji. The distribution north of Christmas Island is 
discussed in the interisland subsection. The April north pelagic da^a is 
of some interest. As can be seen on the plot on Graphs 7C and loB, birds 
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