SUMMARY 
Cooperative studies were conducted on a New Jersey salt marsh in 
1949 to ascertain the effects upon wildlife of DDI sprayings comparable to 
those applied for control of mosquito larvae. Four study areas were estab- 
lished and treated by plane at rates of 1.6, 0.8, 0.4 and 0.2 pounds of 
IDT per acre respectively. Sprayings were made at two periods: August 17- 
19 and September 15-16. The study plots were 90 to 100 acres each except 
for the one of highest dosage (1.6 1b. per acre) which was only 50 acres. 
A check area was also established. Population appraisals were made before 
and after spraying to determine the extent of mortality, if any. In brief, 
direct harmful effects upon birds were not evident but mortalities of fish 
and of organisms important as food sources for wildlife were commonly 
heavy, especially where the two higher dosages were applied. A summation 
of effects on each of the animal groups studied follows: 
Birds 
No harmful results to birds were noted except that populations 
of swallows declined in the areas receiving the heaviest dosages. Presum 
ably these decreases represented movements away from the treated plots. 
Gulls flocked into areas where quantities of DDT-killed fish and crabs 
were available. However, no evident harm resulted to these birds nor to 
clapper rails feeding on dead fiddler crabs. Land birds, such as the 
long-billed marsh wrens, sharp-tailed sparrows, and seaside sparrows, 
successfully reared their young in sprayed areas and apparently found 
sufficient food. 
Fishes 
Mortality to fishes appeared to depend largely upon the DDT 
dosage. The 1.6 pounds per. acre application caused a nearly complete 
destruction of killifish in shallow ponds but survival was greater in 
deeper ones. Considerable mortality occurred in creeks and ditches but 
here it was far from complete. The kill in the 0.8 area was judged to be 
half of that in the 1.6 area. The other two areas sustained only light 
mortality as determined by general observations. However, an 86% mortality 
was observed in an enclosed creek-section study under a 0.) dosage, indi- 
cating heavy losses to fish that are confined within a sprayed area. As 
a rule, small fish proved to be more susceptible than large fish and 
Cyprinodon killifish were able to withstand DDT applications better than 
fundulus killifish. 
insects 
Insects of nine orders frequenting the saltmarsh habitat were 
severely reduced in numbers by the sprayings, the destruction being 
generally in proportion to the dosage applied. Three weeks after the first 
spraying, in areas where 1.6 and 0.8 pounds per acre of DDT were used, 
insect populations varied from one-fifth to four-fifths less than formerly. 
Six to seven weeks later, populations in the 1.6 and 0.8 areas showed still 
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