Table 2. Mean PCB and DDE residues (ppm lipid weight) in seabird eggs from the Strait of 

 Georgia, the west coast of Vancouver Island, and the Queen Charlotte Islands in British Col- 

 umbia, 1970 (K. Vermeer, unpublished data). 



0.34 ppm in all but one sample. Dieldrin and 

 HCB were present in seven samples, but 

 neither exceeded 0.36 ppm. 



In a survey of organochlorine residues in 21 

 aquatic bird species at 31 locations in Alberta, 

 Saskatchewan, and Manitoba, DDE and diel- 

 drin levels were higher in eggs of larids and 

 fish-eating birds than in those of geese and 

 ducks, presumably reflecting different trophic 

 levels between those two groups of birds (Ver- 

 meer and Reynolds 1970). 



On the Niagara Peninsula, an area of On- 

 tario that is intensively developed for agricul- 

 ture and heavy industry and has a large urban 

 population, eggs were collected in 1972 from 

 20 species of birds having a variety of feeding 

 habits (Frank et al. 1975). Representative 

 species were obtained from both the terres- 



trial and aquatic food chains. Highest total 

 DDT residues were in the eggs of aquatic car- 

 nivores, including common tern (22.4 ppm), 

 herring gull (10.4 ppm), black-crowned night 

 heron (Nycticorax nycticorax; 7.8 ppm), and 

 black tern (Chlidonias niger; 7.6 ppm). Herbi- 

 vores and insectivores contained lower total 

 DDT residues regardless of the environment 

 in which they fed. The highest mean residues 

 of PCB's also were in carnivores in the aquatic 

 food chain, including herring gulls (74 ppm), 

 common terns (42 ppm), and black-crowned 

 night herons (27 ppm). 



Eggs of anhingas (Anhinga anhinga), 

 herons, and ibises were collected during the 

 1972 nesting season at coastal and inland lo- 

 calities from Florida to New Jersey (Ohlen- 

 dorf et al. 1974). Measurable residues of DDE 



