Color phase ratios were derived in breeding birds by two methods. 
In the first method, Balcomb and Chandler, who took the nest count, 
simply recorded the color phase of all birds present on nests counted. 
In the second method color phases of all birds banded or returned from 
nests were recorded and the subsequent ratio noted. The first method, 
resulted in a ratio of 88/4 intermediate phase birds and 125a white-phase 
birds (n=25) whereas in the second method the resulting ratio was 
93/4 intermediate-phase birds to 7% white-phase birds. The two ratios 
seem quite comparable considering the limited sample sizes. The ratio 
found on Howland is distinctly different from the 93.3 % intermediate 
phase to 1.7?4 white-phase ratio (n*59) found on Jarvis in the same 
month. 
Brown Booby ' Estimated population : 80 +> 5% 
( Sula leucogaster ) Estimated breeding population-: 26 4- 5/4 
Estimated roosting population -: 55 ± 5% 
Nest count: total nests counted -: 10 
Nests with eggs---: 5 
(Nests/le:2 ; Nests/2e:3) 
Nests with small downy young -: 1 
Nests with large downy young -: 4 
Estimated % nest count complete *-: 70% 
Number of returns---—--: 4 
Number banded-----*—: 5 
Several of the Brown Booby egg clutches examined were fresh indicating 
continued nesting activity in August. As on most other SIC visits the 
primary nesting concentration(where usually over 90/4 of all nests are 
located)was at the southwest corner of the island. 
A very few Brown Boobies were roosting with the Blue-faced Boobies in 
the northern-most of the four Blue-faced Booby clubs recorded. 
Great Frigatebird 
( Fregata minor ) 
Estimated population-*—— 
Breeding population —-------- 
Nest count: total nests counted - 
Nests with eggs---—---< 
Nests with small young - 
Nests with medium young —--- 
Nests with large young —*-~< 
Estimated % nest count complete - 
370 
320 
150 
11 
17 
96 
26 
95/o 
+ 
4 - 
10 % 
10 % 
0 / 
Berlese samples taken - 
10 
The slight increase in nesting population from July to August stems 
