April 1968 No. 8 
A MILLION SOOTY TERNS 
NEWSLETTER OF THE PACIFIC OCEAN BIOLOGICAL SURVEY PROGRAM, SMITHSONIAN INSTITUTION, WASHINGTON , 0. C . 
The Sooty Tern is the most 
abundant bird in the tropical 
Pacific Ocean. From islands off 
the coast of Mexico across the 
Pacific to the Philippines it is 
known to _breed, or has at one time 
bred, on most island groups in the 
tropical Pacific. It reaches its 
greatest abundance in the central 
Pacific where individual colonies 
sometimes contain more than a 
million birds . Fishermen rely on 
large flocks of Sooty Terns to tell 
them where their fish schools are. 
The eggs of this bird are gathered 
each year at many colonies for food. 
In spite of the abundance and 
wide range of this bird, biologists 
are puzzled about many of its 
habits. For this reason, POBSP 
field workers have banded over a 
million Sooty Terns in the central 
Pacific. Among the questions the 
POBSP hopes to answer with these 
banded birds are these: Where do 
Sooty Terns go when they leave 
their island after breeding? Do 
birds from different islands spend 
their nonbreeding seasons in 
different places? Do the birds of 
one island stay together at sea 
when they are not breeding, or do 
they mix freely with birds from 
other islands? How old are Sooty 
Terns when they first start to 
breed? How long do Sooty Terns 
live? Do Sooty Terns that are not 
old enough to breed follow differ- 
ent migration routes from breeding 
birds? These questions will not 
be answered overnight. They will 
require careful compilation of 
facts based upon all the bands 
that our collaborators recover 
throughout the Pacific Ocean. 
What are the chances of re- 
covering a banded Sooty Tern? In 
spite of the immense numbers band- 
ed, the total population is so high 
that the chances of any one Sooty 
Tern being banded are considerably 
lower than for other birds such as 
frigatebirds or boobies. However, 
a million banded birds are some- 
where in the Pacific waiting to be 
recaptured. 
Some Sooty Tern recaptures 
have already been reported, and we 
are very thankful to those who have 
contributed them. Many more will 
be needed before biologists can 
piece together the patterns of 
