(Lin. Dens. .50) Pterodroma density for this section was eight times 
greater than that for the northern section (A)* Pterodroma were 
seen in small feeding flocks and as scattered individuals# Wedge¬ 
tailed Shearwaters were approximately as frequent as Pterodroma 
(Lin# Dens* #U8) 
The relatively high linear density for this area is due to a 
layge concentration of feeding flocks in the region referred to as 
M 9 N n • Other cruises have noted similar concentrations between 
3° and 8 north latitude. This region is evidently a buffer zone 
between two major ocean currents and is undoubtedly richer in food 
sources than surrounding waters. In an attempt to illustrate and 
quantify this observation I have constructed a tabular analysis of 
the data as follows: ^ach day is divided into 3 hour segments 
0600-0900* 0900-1200, 1200-1900, 1900-1800. In each 3 hour segment 
the total number of individuals and the number of species is determined 
The log of the product of these two figures can be plotted against 
distance (ordinate)# It is hoped that this would represent the food 
availability (number individuals) as well as the ecological diversity 
(number species) (see Table #9). A further refinement to this index 
would be the inclusion of a flocking factor, for instance, a third 
multiplicand (”2*for a flock of 9-90, "3" for a flock of 90-100, etc.). 
An index similar to this, if shown to be reliable, could serve as a 
general characterization of the avian ecology of ocean regions# 
SECTION C: Number of Birds 3*792 
Number of Miles 1,097 
Linear Density 3#U2 
Number of Species 31 
During September 29-27 and October 6-11 observations were 
generally in the vicinity of various islands in the Phoenix group a nd 
the data represent the breeding populations of these islands. 
Between Samoa and the Phoenix islands, bird observations dropped to 
a low of 12 birds/day (October 9*)* Heavy seas and rough weather 
between the kth and 7th of October made observations difficult. 
Concentrations of Terns, Red-footed Boobies and White-tailed Tropic- 
birds were recorded within 79 miles of Samoa. 
SECTION D: Number of Birds 1,190 
Number of Miles 869 
Linear Density 1*38 
Number of Species 27 
Very calm seas on the 18th of September gave way to increasingly 
rough seas to the north# Again a peak of activity was noted in the 
