15 



occurred in all 209 eggs. The highest mean 

 value (4.0 ppm) was found in great egrets 

 from New Jersey. Among the coastal locali- 

 ties, levels of DDE as well as total DDT pro- 

 gressively declined toward the south. The 

 PCB's occurred second most frequently and 

 also reached their highest mean level 

 (4.2 ppm) in the great egret eggs from New 

 Jersey. Other pollutants occurred less fre- 

 quently and at lower levels. 



In Great Britain, where the presence of or- 

 ganochlorine pollutants in seabird eggs was 

 first demonstrated (Moore and Tatton 1965), 

 organochlorine residues in seabird eggs from 

 a number of colonies have been monitored. 

 Populations of common puffin (Fratercula arc- 

 tica) in Great Britain declined (Flegg 1971, 

 1972), but those birds analyzed have not 

 shown excessively high contamination levels. 

 Birds from Saint Kilda contained 7.6 ppm of 

 PCB (61 ppm in fat), but seven other puffins 

 contained lower concentrations. Five eggs ob- 

 tained from Saint Kilda in 1969 contained 

 lower residues of PCB's, DDE, and dieldrin 

 than did eggs of either the common murre or 

 the razorbill (Par slow et al. 1972). Eggs of the 

 murre from Lundy, Skomer, and Berry Head 

 contained lower PCB levels than did eggs of 

 the kittiwakes from the same location, but 

 DDE levels were lower in the kittiwakes 

 (Parslow 1973). In some localities on the Brit- 

 ish coast, eggs of murres contained levels of 

 PCB's that were as high as those reported 

 from California and the Baltic, but DDE 

 levels were lowest in Britain. 



Biological Effects of 

 Organochlorines on Marine Birds 



Although there is a considerable amount of 

 information on residue concentration and re- 

 productive effects of organochlorines in ma- 

 rine birds, there is relatively little information 

 on toxicology, physiology, and pathology in 

 these species. Therefore, it is particularly rele- 

 vant to consider also such effects in the more 

 frequently studied terrestrial species. 



Toxicology, Physiology, and Pathology 



Evidence is substantial that PCB's may 

 have contributed to the mortality of contami- 

 nated birds. Great cormorants found dead in 



the Netherlands may have died of PCB 

 poisoning (Koeman et al. 1973). Residues in 

 the brain and liver were equivalent to those in 

 birds poisoned through feeding of the PCB 

 preparation Clophen A60. Chlorinated diben- 

 zofurans, however, were present in the com- 

 mercial PCB mixture (Vos et al. 1970) and 

 may have contributed to the mortality of the 

 experimental birds. Therefore, the residue 

 levels in tissues may not be equivalent in the 

 toxicological sense. 



The occasional "wrecks" of seabirds, par- 

 ticularly of common murres, are usually asso- 

 ciated with storms. In 1970 more than 

 100,000 murres died in Bristol Bay, Alaska, 

 following stormy weather (Bailey and Daven- 

 port 1972). There had been no oil spills in the 

 area. The birds were emaciated and appar- 

 ently had starved as a result of an inability to 

 find food during the prolonged storm, but 

 they were not analyzed for organochlorines. 



In Great Britain, PCB concentrations in the 

 livers of gannets (Moms bassanus) that died 

 during large-scale mortality incidents in 1972 

 ranged from 3,300-9,600 ppm, lipid weight; 

 DDE concentrations ranged from 260- 

 520 ppm, lipid weight (Parslow et al. 1973). 

 Organochlorine concentrations of this magni- 

 tude might contribute to the death of marine 

 birds either through direct poisoning follow- 

 ing mobilization of fat or through more subtle 

 sublethal effects on the birds at a time of en- 

 vironmental stress. 



Because concentrations of chemicals in the 

 body are greatly affected by weight gains and 

 losses, it is sometimes more useful to compare 

 total body loads. Estimated body contents of 

 PCB's and DDE in five murres found dead 

 during a 1969 wreck in the Irish Sea were 

 2,700 /xg (range 800-8,900) and 673 /ig (314- 

 1,535) (Holdgate 1971). Five birds that were 

 shot in the same general area had 3,500 jig 

 (800-7,200) of PCB's and 1,484 /*g (468-3,211) 

 of DDE. However, eight other murres that 

 died in the wreck had an average estimated 

 body burden of 4,660 /*g of PCB, twice as 

 much as in nine other apparently healthy 

 birds that were collected (Parslow and Jef- 

 feries 1973). Depletion of body fat during 

 times of hunger could be expected to mobilize 

 chlorinated hydrocarbons, providing addi- 

 tional stress when the birds are poorly 

 equipped to cope with it. The overall contribu- 

 tion of chlorinated hydrocarbons, particularly 



