Twenty-five Sooty Terns were collected within three miles of How¬ 
land Island on the evening of April 6. These birds were all coming from 
seaward heading toward the island. The primary objective was to ascertain 
as far as possible the stage of development in the reproductive cycle. 
The 25 specimens included 16 males and 9 females. The left testis of 
the males ranged in size from 4x2 mm. to 12 x 4 mm. with an average of 
7.5x3 mrn. Although the testes were not checked for spermatozoa, it is 
thought they were below the maximum breeding size. Seven of the males 
had brood patches forming (43%) and 4 females had brood patches (44%). 
Of the females examined, only 3 showed evidence of the oviduct enlarging 
while several showed ova of 2 mm. in size. 
The evidence presented above suggests that the Sooty Terns will pro¬ 
bably be on eggs within a month 1 s time but past experience shows the 
breeding cycle to be highly unpredictable. 
One banded Sooty Tern was taken (793-48690) just off the beach at 
Howland. The tern had been banded at Howland Island in February 1965. 
Another band was taken later at-sea near Baker Island and was also a 
Howland Island bird banded in February 1965. 
We were unable to make any accurate counts of other species but the 
frigatebird (toofar to tell species) numbers circling over the island 
appeared to be up considerably in number from mid-March. The usual 
number of Brown Boobies, Blue-faced Boobies and Red-footed Bo )bies were 
seen around the island. 
Max C. Thompson 
Biologist-in-charge 
Island Section 
