Reproduction in a DDT -contaminated herring 

 gull population. — The University of Wisconsin, 

 under contract with tlie Bureau, reported mean 

 wet-weight residues in 12 nesting herring gulls 

 as follows: in body fat, 390±46 ppm of DDT, 

 1,925 ±37i of DDE, and 126.4 :t 16.9 of DDD. Of 

 these gulls, 11 were collected on nesting islands 

 in Green Bay in 1963, the 12th on the Lake Michi- 

 gan side of the Door County peninsula in 1961. 



Nine eggs taken from nine different nests on 

 Sister's Island, Green Bay, early in the incubation 

 period of 1964 averaged (wet weight) 19±3 ppin 

 of DDT, 202±34 of DDE, and 6.0±0.9 of DDD 

 (total 226.8±:38.2). Nests at this one colony were 

 systematicall}- checked from May 25 to July 17. 



Reproductive success in the 114 nests involved 

 was 0.41 young fledged per breeding pair, the low- 

 est thus far found for this species. Mortality in 



the present sample of eggs was spread rather 

 evenly tlirough the 27-day incubation period, and 

 the high residues of DDT and its metabolites in 

 them appear to represent the causative factor for 

 low reproductive success in 1964 in the Green Bay 

 area. 



Fate and persistence of DDT in a forest envi- 

 romnent. — The persistence of DDT in a forest 

 habitat and its diffusion in a forest ecosystem was 

 determined from an application of DDT in Cali- 

 fornia, made in cooperation with the U.S. Forest 

 Service, the University of California, and the 

 California Department of Fish and Game. 



Ten samples each of four plant species, two 

 soil materials, five birds, and one mammal were 

 collected before treatment, on the daj' of treat- 

 ment, and 6 weeks and 3 months after treatment. 

 Low residues of DDT and its metabolites were 



General view of the i)esticide analytical laboratory, Denver Wildlife Research Center. (Photo by James B. Peterson) 



44 



