4 
The actual chick density of the nesting colony could not be deter¬ 
mined, on this visit, because of immature birds flying or not remaining 
in their nesting territory when I approached the nesting colony. Eggs 
which did not hatch and dead chicks were found in the Colony so Balcomb's 
nesting density figure of one nest per 4 square feet would be too dense to 
use for figuring chicks successfully raised. Any density figure could be 
divided into the total square feet in the population. If you assumed a 
density of one nest per 5 square feet, then 97 , 875 chicks were successfully 
raised on Howland during this period. 
The Sooty Tern colony is actually divided into several subpopulations. 
These subpopulations can be seen by referring to Diagram 1. Estimates 
were made of the percent of flying birds in all areas; these percentages 
vary from 90 to 25 percent. This indicates egg laying occurred over a‘ 
period of two or more weeks, as different groups of birds came down at 
different times, enlarging the colony in suitable nesting areas. 
The nesting colony was in areas where Lepturus was growing. Other 
adjacent areas of Digitarium were avoided because of dense vegetation, 
The colony outline roughly follows a belt of Lepturus running adjacent to 
the old runway. Digitarium acted as a barrier to nesting and actually 
separated the nesting colony into four unconnected nesting areas. Sooty 
Terns cannot successfully scratch out a nest site in larger grasses. 
Each evening a swirl of Sooty Terns formed over the 'north end of the 
island. Numbers slowly increased, starting after the hotter part of the 
day. This swirl was estimated to be about 10,000 birds. The swirl.was 
still present at midnight each night, but gone by morning. 
New Sooty Terns banded totaled 3700; four local returns were recorded. 
Shorebirds 
I II — — ' - " 1 ' k 
The following^shorebirds were counted: 
Golden Plover 80 
Ruddy Turnstone 30 
Wandering Tattler 10 
Bristle-thighed Curlew 3 
Cat 
One dead cat was found on the south beach; it appeared to have died 
witjain the last^month. One medium sized ca^ was ^een near the Sooty Tern 
colony 9 Several evidences of Soot^ Terns eaten by a cat; were found. 
