
these birds. In order to establish their nesting territories on the 
ground the sooty terns apparently require open areas between trees and 
shrubs or other obstructions plus a naturel earth surface. ‘This 
knowledge suggests two possible methods. 
Wire mesh ground cover.--A strip of galvanized wire mesh was 
placed over the ground where sooty terns were landing in March 1957. 
Where the wire mesh was held firmly above the ground the birds were 
repelled. Where the wire sagged and touched the ground, the birds 
landed. Although wire mesh could be used to prevent successful nest- 
ing, we believe that, in view of the large areas that would have to be 
covered, the excense of the material, anc the considerable labor in- 
volved in installation and maintenance, this control measure is 
impractical. 
Black-top surfacing.--It has been demonstrated on Sand Island 
thet sooty terns do not nest on hard-surfaced areas. In view of this 
knowledge it is possible that the current extensive program of surfecing 
for water catchment in areas adjacent to Runway 6-24, will exclude 
sooty terns from areas where they nest at present and constitute a 
potential problem to aircraft. Advantage will be taken of this 
opportunity to make observation which should give the answer as to the 
effectiveness of this type of habitat modification. Hard surfacing of 
the ground for a sufficient distance on both sides of operational run- 
ways might keep the nesting birds far enough away so that they would 
not be a hazard. It is not known what this distance wouid have to be, 
however, but it is certain that it would be very costly and probably 
not feasible unless combined with some other purpose such as water 
catchment. 
Poisoning 
Two experiments were conducted to test the effectiveness of 
TEPP (tetraethyl pyrophosphate), a strong contact poison affecting the 
nervous system, in eliminating sooty terns. Captsin 0. M. Trier of 
the U. S. Army Chemical Corps cooperated in these experiments and 
supervised the handling and application of the poison. 
Experiment 1.--On June 4 at 7 a.m., shortly after sunrise, 
all sooty terns and their eggs in an area 50x50 feet, in the center 
of Zone 5, were sprayed with a 3 percent stock solution of TEPP-40 in 
water. A small amount of a chemically inert wetting agent, E51-c-1063- 
165, was added. The area sprayed contained approximately 290 eggs and 
580 sooty terns. 
Care was taken to saturate the plumage of many birds, and all 
those which remained on the ground (estimated at more than 50 percent) 
were sprayed about the eyes and into the open mouths from a range of a 
few inches. All eggs were saturated with the spray. All birds re- 
turned and settled on their eggs within 3 to 5 minutes. 
49 
