20 
et al. 1978b) were, in general, similar to those in eggs from 
Alaska. The most frequent difference was that concentra- 
tions of PCB’s in the eggs from British Columbia were 
slightly higher than in those from Alaska. 
White and Risebrough (1977) analyzed eggs and tissues 
of several seabird species from Amchitka and Agattu 
(Aleutian Islands); however, because of variations in the 
manner of reporting residue concentrations and the small 
sample sizes, it is difficult to make direct comparisons 
between our results and theirs. They suggested that local 
sources of PCB contamination (including the disposal of 
PCB-containing refuse on beaches) appeared to be a more 
plausible source of PCB’s in Alaskan birds than did atmos- 
pheric or oceanic transport of these chemicals from Japan. 
In a small sample of representative prey species of pere- 
grine falcons (Falco peregrinus) from Amchitka, concen- 
trations of DDE in the migrant prey species averaged 2.8 
times greater than in resident species sampled (White 
et al. 1973). 
Eggs of eleven species of marine and estuarine birds 
were collected in Oregon during 1979 (C. J. Henny et al., 
unpublished data). Seven species showed geometric mean 
concentrations of DDE that were less than 1 ppm, and 
mean concentrations of PCB’s in eight species were below 
1 ppm. 
Concentrations of DDE (about 41 ppm, converted from 
concentrations reported on a lipid-weight basis) and PCB’s 
(about 23 ppm) in eggs of common murre from the Faral- 
lon Islands, California (Gress et al. 1971) were about two 
orders of magnitude higher than in eggs of either species of 
murre from Alaska. Coulter and Risebrough (1973) re- 
ported that eggs of the ashy storm-petrel (Oceanodroma 
homochroa) from that site also contained higher concen- 
trations of DDE (about 62 ppm) and PCB’s (about 38 ppm) 
than did eggs of either species of storm-petrel from Alaska. 
The Farallon Islands are relatively near local sources of 
pollution that may have contributed some of the organo- 
chlorines found in eggs of these seabirds, 
A comparison of DDE and PCB concentrations in eggs 
of several species of seabirds from Iceland (J. A. Sproul 
et al., unpublished data) and our samples from Alaska 
suggests somewhat higher concentrations of residues— 
especially PCB’s—in the Icelandic birds. Concentrations 
of PCB’s in the eggs from Iceland were sometimes an order 
of magnitude higher than in those from our study and the 
ratio of PCB to DDE was often two to four times that in 
Alaskan eggs of the same or comparable species. In eggs 
from Iceland, as in our samples from Alaska, the ratio of 
PCB to DDE was higher in the black-legged kittiwake 
than in any other species. 
Organochlorine concentrations in eggs of Leach’s storm- 
petrel, double-crested cormorant, common murre, and 
Atlantic puffin (Fratercula arctica) collected in eastern 
Canadian coastal waters in 1970-76 (Pearce et al. 1979) 
were almost always higher—frequently by at least an 
order of magnitude —than in the eggs of these or related 

species we analyzed. However, the ratios of PCB to DDE 
were similar to those for eggs from Alaska. 
Concentrations of DDE and PCB’s in eggs of black- 
legged kittiwake and common murre were considerably 
higher along the coasts of the British Isles (Parslow 1973) 
than in Alaska. The ratio of PCB to DDE in murre eggs 
ranged from 5.0 to 8.9. In kittiwakes the concentration of 
PCB’s was 18 to 50 times that of DDE in the eggs. The 
mean concentration of PCB’s was usually higher in kitti- 
wake than in murre eggs, but DDE concentrations were 
much higher in murre eggs at all colonies. Parslow (1973) 
suggested that these differences were related to differences 
in the birds’ feeding ecology and consequently to different 
levels of exposure to each of these organochlorines. In 
Britain, murres seemingly feed on small fish in the inshore 
marine zone throughout the year, whereas kittiwakes feed 
mainly on macrozooplankton living on or near the surface 
in offshore and pelagic zones. 
Among more than 100 birds collected from the open 
North Atlantic between Scotland and the Arctic (Bogan 
and Bourne 1972; Bourne and Bogan 1972), the total 
organochlorine content in muscle and liver of the auks and 
the few shearwaters examined was generally low—0.1- 
1.0 ppm (wet weight?). Concentrations were higher (gen- 
erally 1-10 ppm) in the more pelagic species, including the 
black-legged kittiwake, northern fulmar, and British 
storm-petrel (Hydrobates pelagicus). The highest concen- 
trations, often above 10 ppm, were found in large gulls 
and skuas feeding largely around trawlers in the winter 
and seabird breeding colonies in the summer. The highest 
concentrations were found in glaucous gulls (Larus hyper- 
boreus) breeding near other seabird colonies, where they 
apparently fed largely on eggs of other seabirds. 
The ratio of PCB to DDE was usually between 2 and 10 
to 1 in all species except black-legged kittiwake, in which 
the ratio was always higher (sometimes at least 60 to 1). 
This finding suggested to Bogan and Bourne (1972) that 
kittiwakes have a food source higher in PCB’s than the 
food of the other species, that winter distribution of the 
species is different, or (less likely) that kittiwakes metabo- 
lize or excrete DDE more rapidly than the other species. 
The concentration of DDE in five Atlantic puffin eggs 
collected on St. Kilda (Outer Hebrides, Scotland) in 1969 
averaged 0.18 ppm —about one-third the concentration 
(0.47 ppm) in whole birds (Parslow et al. 1972). PCB’s in 
these eggs apparently did not exceed 0.5 ppm. These con- 
centrations are similar to those we found in eggs of puffins 
from Alaska. 
Residues of DDE and PCB’s occurred in each of 203 sea- 
bird eggs collected from 10 localities along the coast of 
Norway by Fimreite et al. (1977). Although some varia- 
tion in DDE concentrations among sampling sites was 
noted, there was no south-north gradient. DDE concen- 
trations were highest in herring gull (Larus argentatus), 
lower in common murre and razorbill (Alca torda), and 
lowest in black-legged kittiwake. Within sites and species, 

