when scanning tern flocks. Sooty and Slender-billed Shearwaters are 
similar except that the dominant species alternate seasonally. The alter 
nation is for practical purposes complete. The large numbers of fall 
slender-bills dwarf the small numbers of sooties and in the spring the 
virtual absence of slender-bills leaves moderate sooty numbers. The 
dramatic change is however mostly due to the slender-bills as sooties are 
present in both seasons. While six slender-bills were recorded I raise a 
Question on their validity as all the records were made by one observer 
and based (evidently) only on the criterion of underwing color which is 
r.ou sufficient in my mind. 
Sooty Shearwater, I feel, is with 95 percent confidence, the species 
under discussion in the present data. Despite the possibility that the 
bulk of the northward migration passes through the area before late April, 
the data show a definite concentration of birds in the southeast section. 
In view of the fall i 960 data which show a similar sooty concentration 
(lower numbers) in the same area I hypothesize a vague northeast-southwest 
route from the Australian breeding grounds to the northern nonbreeding 
areas. It appears feasible that sooties use an "island hopping" route 
similar to that hypothesized for slender-bills, and that southwest Pacific 
populations stream northeast in the spring to join the South American pop¬ 
ulations moving north off the American coast. The return route may be 
similar or possibly a more circuitous, oriental pattern may be taken. 
Christmas (Csland) Shearwater # Obs. = 8 
Poffinus nativitatis ' 
This bird is mysteriously "absent" almost everywhere. The dark color 
and low-flying habits make this probably the most regularly overlooked 
species in the central Pacific. 
The eight records consist of l) A bird collected from the skiff 
(5° N.); 2) Two birds in a flock off Christmas Island; 3) Five birds ob¬ 
served from a small vessel on 5 April. Aside from the two birds seen 
some 15 miles from the species' main breeding colony, there are no other 
observations from the large vessels. Evidently the size of the ship is a 
critical factor for this species. Probably the observer eye-height and 
a "ship-shyness" are the factors involved. 
Probably birds disperse from Christmas Island and follow the 5° N. 
countercurrent east and west. (See also the report on Eastern Area Cruise 
13.) 
Newell Shearwater # Obs. = 13 
Puffinus puffinus 
Ail birds were seen in the north pelagic region. Six birds were 
spread out in the 5° N. section and five birds were seen on March 13 in the 
12° N. section north of Palmyra. The trend for birds to be found to the 
east of the usual Oahu to Howland track may be significant. ^ suspect it 
reflects a sizable breeding population on the eastern Hawaiian Main Island 
