Most of the breeding Brown Boobies (78 birds) nested on the southwest 
corner of the island where they have nested most abundantly in the past. 
Two pairs nested somewhat inland on the open coral rubble area along the 
^o^u 1 im of che island 1 six pairs nested near and Just northwards from 
i^e three small dire mounds near the southeast corner of the islandj three 
pairs nested in the interior of the island near the south edge of the 
ua jor po_l oion 01 one dead oPraia grove* This may have been the first time 
that these boobies have nested in so interior a location. 
Although the estimated total population present is probably not sig¬ 
nificantly larger than other recorded peak populations (100 in July and° 
October 1963 ^ October 1965, February 1966 , September 1966 , and 125 in 
November^ 1966 ), the nesting population is the largest yet recorded. The 
oni y Periods in wnich the nesting population has nearly approached the 
P^.e^c-it level were February a 9 66 when 85 Brown Boobies were nesting and 
Novemoer iyuo wnen 92 were nesting. Table 3 below presents a comparison 
of the nest counts made on the four' July visits to Howland. As has been 
indicated previously one Howland Brown Boobies do not appear to have an 
annual cycle. 
Table 3 . Comparisons of July nest counts of Brown Boobies on Howland 
Island in 1963 * 1965, 1966 , and 1968 . 
12a. 
196 ^ 
1966 
1968 
Dates of visit 
July 6-8 
July 22-25 
July 12-22 
July l6-l8 
Estimated population 
100 
70 
80 
110 
Breeding population 
16 + 
16 
30 
100 
# of nests counted 
8+ 
8 
15 
50 
c jo of nests/eggs 
? 
• 
25$ 
53$ 
68$ 
70 of nests/young 
c.100$ 
75$ 
W$ 
32$ 
All eggs excepting 
one nest that 
contained two 
eggs were 
I..-,; 
tested for 
- W ' --- " '-'OO'-' " ^ 
suage of Incubation by flotation. A strikingly-high proportion of the eggs 
were rotten (27 of 67 or 50 percent) which suggests, (as does the low pro¬ 
portion of small young Blue-faced Boobies in that nest count) that these 
Dirds underwent adverse nesting conditions a month or so prior to our visit 
m all 18 sets of eggs were tested in which none of the eggs were 
rotten. All three one egg clutches were fresh. In the fifteen nests con¬ 
taining two eggs, one set (7 percent) was fresh, 5 (27 percent) were very 
slightly incubated, 2 (13 percent) were slightly incubated, 5 (33 percent) 
were moderately incubated, and 3 (20 percent) were heavily incubated. If 
tne stage of Incubation, the presence of a single viable egg from two egg 
clutches in which one egg was rotten and the somewhat higher proportion of 
young a month or less old, are considered It would appear that there was 
an egg peax about a month and a half to two months previously, or about 
flay. Clearly, however, the presence of near Immatures indicates that some 
eggs were laid at least four and one-half months earlier, or in late Febru¬ 
ary or early March. The presence of fresh eggs and empty active nests in 
iM* S5w*«»lt 
