Sooty Tern Estimated population -: 200,000 
(Sterna fuscata) Estimated it of nests with eggs-: 1,500 
Estimated it of small downy chicks-: 13,000 
Estimated it of larger, feathered chicks: 30,000 
Estimated it of flying immatures--: 12,000 
Number banded:(4,500 A-U, 13,500 L-U)-: 17,500 
Number of returns-* 285 
Sera samples collected- • 25 
Specimens collected —--*-- - 26 
The number of Sooty Terns on Howland Island has not changed much since 
July. The major change encountered was the predominance of large chicks 
which was expected from our earlier observations. The large numbers of 
chicks present and the low incidence of rotten eggs indicate a very 
successful nesting season despite^d/en days disturbance by the P0B3P field 
party in July. 
The rapidly growing vegetation (mainly Tribulus ) seems to have had 
little effect on the terns. In July, most of the area occupied by the 
colony was devoid of vegetation* The colony is now literally covered 
with a stand of four to 18 inch Tribulus . One section of the colony 
contained about 1,000 fresh eggs and another section contained about 150 
more (indicating that Sooty Terns will probably be present in September. 
If the growth of the vegetation continues it may very well prevent future, 
egg laying and may effect terns in the early stages of the breeding cycle* 
Two swirls containing about 5*000 terns each were observed over the 
island each night*. These birds may have been preparing to lay eggs in 
the present colony. Each swirl formed about 1600 and reached its numerical 
peak by about 2100. By 0200 the swirls had broken up (and possibly 
settled down in the colony?) 
The number of adult birds in the colony rose from a low of about 
20,000 in the morning to about 100,000 at dusk with the sharp increase 
coming in the late afternoon. By'about 0200 the colony seemed to have 
about twice the number of adult terns as it did at dusk* 
About 1,200 flying immatures and their parents roosted on the coral 
rubble along the northeast beach. Several streamered immatures and 
adults were always present in this group. On the night of August 17th 
Balcomb collected a full albino immature in this area. 
The thick vegetation made possible the banding of 13,500 chicks 
and we beleive this number represents about 30% of the total present. 
* 25 of these specimens were collected for ectoparasite studies. 
