Cook’s Petrels were seen in small numbers. 
Sooty Terns became the dominant bird in area B with Leach’s 
Storm Petrel still common and a scattering of shearwaters and petrels. 
The greatest number of birds were seen near 10°N. On the return trip 
along 12o°W, the species composition did not change much, but large 
numbers of birds were seen from 3°-10°N instead of being concentrated 
in one small area. 
Areas C and E were similar in species composition with the Sooty 
Tern still the dominant species and Leach’s Storm Petrel decreasing. 
Shearwaters and petrels were almost absent from these areas. On each 
leg there were concentrations of birds between 10°S and 15°S. A 
secondary concentration was found at 7°S on the eastern leg, and at 
3°S on the western leg. 
Area D had only a few terns and shearwater-petrels. 
The abundance of birds this trip does not appear to correlate 
very well with the current system in the region. The Equatorial 
Countercurrent was found between 2°N and 6°N this trip. On the 
eastern leg birds were most abundant north of the Equatorial Counter- 
current with very few birds at the edges or in it. While on the 
western leg they were common north of it, south of it, and in it. 
The secondary concentrations of birds in the Southern Hemisphere 
were not related to any special feature of the ocean currents, with 
all of them lying in the South Equatorial Current. There was one 
interesting relationship with the Countercurrent. If we plot the 
number of shearwater-petrels seen per day (figure 3 ) an< 3 then delineate 
the area of greatest abundance (i.e., more than ten birds per day) it 
cam be seen that the southern boundary of this area is also the southern 
boundary of the Countercurrent. This relationship is even more 
