to hatch were later collected. In Connecticut, 

 eggs from 2 of 15 nests hatched 4 nestlings and all 

 fledged; 16 eggs disappeared, and 9 eggs failed to 

 hatch and were collected. Correlations between 

 productivity and pesticide residues in eggs and 

 food items remain to be determined. 



NoncJu inicitl methods in mosquito control. — 

 Mosquito control districts along sections of the 

 Atlantic coast of Florida are convinced that per- 

 manent impoundment of marshes is an effective 

 means of controlling saltmarsh mosquitoes. 



Through contract with the Patuxent Wildlife 

 Research Center, the Florida State Board of 

 Health supervised an evaluation of the effect of 

 these impoundments on wildlife. Monthly inven- 

 tories were made of birds using impounded and 

 unimpounded saltmarsh study areas in Volusia, 

 Brevard, Indian River, St. Lucie, and Martin 

 Counties. These counts have shown consistently 

 about 10 times more bird use on impounded than 

 on unimpounded marshes, and the impoundments 

 provide more accessible open water and submerged 

 aquatic plants and fish that serve water birds as a 

 food supply. The necessity of mosquito control 

 through the use of insecticides has declined mark- 

 edly in the vicinity of the marsh impoundments. 



DDT in relation to towhees. — Pesticide research 

 on the rufous-sided towhee was brought from the 

 field into the laboratory in 1963. Studies involved 

 the kinetics of DDT fed to captive birds at differ- 

 ent seasons. Initial findings demonstrated that 

 this migratory species is significantly more vulner- 

 able to dosages of DDT just before and during the 

 breeding season than during the fall. All data 

 are being analyzed at the Massachusetts Unit 

 preparatory to a final report.. 



Malathion S—35 distribution in a small forested 

 watershed. — A 2-pound-per-acre Malathion S-35 

 treatment of a 20-acre forested watershed near 

 Dover, Ohio, resulted in a significant change in 

 small-mammal populations. Although bird be- 

 havior was altered for a few days, several species 



continued to nest on the tract and successfully 

 reared young. No effects were noted on the soil 

 microfauna or on earthworms. Movement of the 

 insecticide into runoff flow was slight. Residue 

 studies carried out in 1963 showed no differences 

 between animals from the treated and control 

 watersheds. Sulfur-35 assay of mammals showed 

 significantly higher quantities in females of all 

 animal groups except birds. Among mammal spe- 

 cies tested, shrews held the highest residues; in the 

 avian fauna, a Baltimore oriole contained maxi- 

 mum values in cmp/mg. Some of the insect fam- 

 ilies containing high residue values included 

 caddis flies, stone flies, soldier flies, and pseudo 

 click beetles. The research was by the Ohio Co- 

 operative Wildlife Research Unit. 



Effects of endrin on vole reproduction in blue- 

 grass meadows. — Endrin was applied by the Ohio 

 Unit to four bluegrass meadows in 1961 and 1962 

 at. rates of 0.6, 0.9, 1.3, and 2.0 pounds per acre. 

 Populations of voles (Microtus pennsylvanicus) 

 were censused in April, before the May applica- 

 tion. Trapping was again conducted 2 and 4 

 months after the insecticide treatment. Specimens 

 were collected for bioassay of residual endrin and 

 for analysis of productivity. Endrin applied at 

 0.6 pounds per acre had no apparent effect on the 

 populations that could be trapped, but the higher 

 rates reduced populations 71 to 95 percent. The 

 sex ratio in the sampled population was not af- 

 fected by the 0.6-pound-per-acre application, but 

 at 2.0 pounds per acre there was a significantly 

 higher decrease among females. Ovulation rates, 

 as indicated by the number of corpora lutea and 

 corpora albicantia, showed no differences as a re- 

 sult of the spray treatment. Treated animals did 

 show a lower percentage, of pregnant and nursing 

 females, and consequently a decrease in the num- 

 ber of litters produced. No endrin was detected 

 in voles taken from the area treated with 0.6 

 pound per acre, while specimens from the 2.0 

 pounds per acre plot contained up to 0.73 p.p.m. 



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