70 
north of 5° N. were recorded relatively regularly, even in the transition 
area. A slight peak was noted in the 5° N. and 12° north areas, but as a 
whole the pattern is more one expected of a migrant population, and in¬ 
deed this is probably the case; birds returning to breeding locations in 
the Kawaiians (Nihoa, etc.). 
Bulwer is another species, like Christmas and Audubon Shearwaters, 
is difficult to observe from large vessels. That such regular num- 
were noted in April (58 birds in 11 ship days) reflects a very sig¬ 
nificant abundance of this species. 
than 
hers 
Leach Storm Petrel 
Oceanoaroma leucorhoa 
ir Ob s„ - 145 
See Graphs 10E 
This ubiquitous species is recorded in the field as "WRSP" = White- 
rumped Storm Petrel, which allows for the possible occurrence of other 
similar species. The other two White-rumped species known to occur in 
the area, Wilson and Harcourt, are only encountered rarely; and both are 
•identifiable in the field by a trained observer. A -more subtle possibility, 
0. tethys , may occur and is much more likely to be overlooked than either 
Harcourt or Wilson. "Leach" Storm Petrels following a ship in the central 
Pacific might conceivably be 0. tethys stragglers from the Galapagos. To 
my knowledge no 0. tethys have been collected in the central area, but it 
would not surprise me to find one mislabled as 0. leucorhoa . Since oc¬ 
casional dark-rumped forms of Leach which breed off the north Central 
Americas do occur, it seems no less likely to expect occasional wanderers 
from the Galapagos to range to the area also. 
With at least 95 percent certainty, however, "WBSP's" in the present 
data are al1 Leach's. Birds were recorded from all 15 pelagic ana inter¬ 
island sections with remarkable uniformity. Of the central Pacific birds 
only Wedge-tailed Shearwater shows a comparable degree of randomness. 
Linear Density _ No. Sections _ General Areas 
ali-Uoc 
.003 
u.0. jl uj 
- .009 
• KJ ^ W UO.VUU 
3 
-L JL ^ U 
Fiji and extreme north 
H 
O 
• 
- .028 
8 
Northern Lines; mid and west central 
.034 
- .049 
3 
Southern Lines; SE pelagic 
.145 
1 
Between Jarvis and Malden 
Avg. 
= .025 
15 
The overall density distribution pattern centers about the equator 
on the eastern edge of the surveyed area, decreases rapidly to the noruh 
and south and decreases slowly to the west. No birds were recorued south 
of 15° S. (Fiji area). North of 15° to 18° N., only a very few Storm 
Petrels are seen and very likely many of these are Harcourt's from 
Hawaiian breeding areas. Just how far birds continue to the west in the 
low latitudes is not known. 
