BLUE-FACED BOOBY - -Annotated List-LISIMSKI 
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L£$ 21 - Aug.31-Sept.5, '67 (BBC-CAE Kept.) 
Blue-faced Booby 
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Population estimate -- 
Number of birds in clubs ■ 
Nests/eggs or downy young - 
Estimated # dependent immatures 
Banded - 
800 
350 
■ . >/; 
Returned 
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Blood-sampled 
none 
~c * 200 
90 (adults) 
- 26 (subadults) 
--- 98 (immatures) 
2lf (total) 
l5f (adults) 
9 (subadults) 
11 (immatures) 
204 (total) 
12 (adults) 
1 (subadults) 
12 (immatures) 
25 (total) 
Four or five clubs were present on the island® The largest, containing 
about 200 birdq was located on the south tip of the island* Most of the 
birds in this club (and in the other clubs) appeared to have fully* adult 
plumage but a small proportion were subadults. Two independent 
immatures (the only ones seen in clubs) and an adult Brown Booby* were also 
seen in this club. 
Another small club of about 15-20 birds was present on the sandy 
southeast beach and a club of about 40 birds was seen several times on the 
southwest beach. A club of about 100 birds was present on the north beach cu 
one night. Another night two clubs each containing about 60 birds were 
seen at the northwest tip of the island. 
We frequently observed small roosting aggregations of about 8 to 10 
birds on the beaches particularly those of the north, northwest, and west 
sides of the island. Most of these aggregations had roughly the number 
of immatures (dependent?) that would account for the number of adults 
present. We suspect that such aggregations represent a stage of the 
breeding cycle intermediate between territory holding and use of club 
areas as roosting grounds. 
Eleven Great Frigatebird chases of Blue-faced Boobies were tabulated 
on the evening of 3 September. In every instance the chase was initiated 
by a female frigatebird but some subadults (white-headed birds) occasion¬ 
ally entered into the chases. In seven of 11 chases only one frigatebird 
chased. The other four chases were by 2 females, 3 females and 1 subadult, 
and by 1 female and 1 subadult. About equal numbers of male and female 
Blue-faced Boobies (5 males, 6 females) were chased but only* 2 of ten 
chases resulted in regurgitation of food by the boobies, (in one instance 
one booby regurgitated three times). 
* Only those boobies that continued to climb in flight were successfully 
preyed upon by the frigatebirds• The rest quickly escaped further perse¬ 
cution by alighting on the beach. The triggering mechanism for these 
chases may well be the relative "heaviness 1 * of flight of the boobies » 
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