
April 12 to April 15. Two men were assigned to harass the 
terns constantly during the night. Since the visits of the Marine 
patrol did not have the effect of keeping the terms constantly off the 
ground, the two men assigned were given shotguns with tracer ammunition. 
The birds were kept off the ground from sunset to sunrise. At dawn most 
of the birds had left the area, but each day the flock began to grow 
progressively larger during mid-morning, and by April 15 some were land- 
ing in the afternoon. 
April 15 to April 22. The watch was changed so that one man 
came on duty at 2 p.m. The second man finished his duty at 2 a.m. On 
April 16, two oil drums were cut in half and placed on the tern's land- 
ing area. Hach half drum was filled with diesel oil and kept burning 
during the entire night. This method, along with shooting, is very 
effective in keeping the terns in the air. 
April 22 to May 11. The biologists turned the project over 
to the Navy, because too much time was being consumed hauling oil to 
the oil burners, and the management of the men was handled by a naval 
officer. 
The experiment was successful in driving the sooty terns away 
from their ancestral nesting area on Sand Islend. The sooty terns were 
unable to land and establish their nesting territories on the area they 
desired until the experiment was discontinued, However, the experiment 
was not successful in driving the terns away from Sand Island to areas 
such as Eastern Island, where they would not constitute a potential 
problem to aircraft. When the frustrated terns were unable to land on 
the erea they desired most, they moved to other areas adjacent to 
Runwey 6-24 and began to ley their eggs almost immediately. The first 
eggs were found in two other areas on May 10 and 11. The harassment 
program was, therefore, discontinued on May 11. Immediately vast numbers 
of terns settled on the harassment area. 
It was coneluded that in view of the vast numbers of sooty 
terns now present at Sand Island, and the considerable amount of man- 
power and materiel expended with negative results, it would be impractical 
to attempt to eliminate the sooty terns from the air over the runways 
throvgh this type of program. We believe the persistent effort put 
forth by the Navy on Midway conclusively demonstrates that, within the 
limits of practicality, sooty terns cannot be driven from their ancestral 
nesting grounds by these methods, 
Habjtat Control 
Sooty terns are most attracted to open sandy areas. However, 
their instinct to retwrm to areas long used by a particular group is 
apparently so strong that they will land and nest successfully on areas 
that become covered with considerable plant growth. We understand that 
this has been the case in certain areas on Sand Island. | : 
An approach to the problem would be to find what types of 
habitat modification will most effectively discourage the nesting of 
h8 
