- 10 - 
The overall density for birds within the grid is much less than was 
to be expected from previous data (See TABLE V). This is largely the 
result of the failure of Sooty/Slender-billed Shearwaters to pass through 
the area in large numbers* Increased numbers ol Pterodroma, especially 
Pterodroma externa, tended to offset the lack ol shearwaters uO a small 
extent. Sooty Terns were also below the expected density level, but 
not drastically as in the above. All other species groups showed 
higher densities than were expected. 
* 
TABLE V 
DIURNAL ABUNDANCE OF SPECIES GROUPS WITHIN THE NORTHERN GRID 
Species Group 
Number 
Birds/Sq. Mi. 
Estimated Pop. 
Expected Pop 
Shearwater-Petrel 
711 
0.U7 
23,600 
44,500 
Tern 
231 
0.10 
5,000 
7,200 
Tropicbird 
30 
0.02 
1,000 
500 
Frigatebira 
22 
0.01 
350 
50 
Storm Petrel 
12 
0.02 
750 
Booby 
b 
0.002 
100 
100 
Shorebirds 
38 
0.05 
2,500 
m 
Jaegers 
6 
0.004 
250 
• 
Unidentified 
8 
0.005 
250 
300** 
Total birds 
1062 
0.68 
33,850 
54,^00 
* See April i960 
Report 
** Includes Shorebird and Jaeger figures 
A cursory examination of the data indicates that bird density was 
highest in the West Quadrant of the grid (almost double tha^ of any 
other quadrant), and lowest in the East Quadrant. 
Relatively few nocturnal birds were seen. The total ol 13o ^see 
TABLE VI) includes a flock of 12 Sooty Terns and 50 Shearwater-Petrels 
about three minutes after sunset on 09 October. This presents a heavy 
bias to the data since, had the ship been moving somewhat faster, we 
