
Highest concentrations of DDD (0.157 ppm), DDT 
(0.140 ppm), and toxaphene (0.101 ppm) were in fork- 
tailed storm-petrel eggs from Buldir Island, and the 
highest concentration of mirex (0.044 ppm) was in fork- 
tailed storm-petrel eggs from the Barren Islands (Appendix 
III). The concentration of DDD was 0.155 ppm in fork- 
tailed storm-petrel eggs from the Barren Islands, and the 
single common loon egg from Kodiak Island contained 
0.120 ppm toxaphene. 
Geographic Differences 
Frequency of Residue Occurrence by Regions and 
Collection Sites 
Considering all chemicals and all species, organo- 
chlorine residues occurred more frequently in eggs from 
the Pribilof Islands (frequency index 0.559) than in eggs 
from any other region; however, only three species were 
represented in the collection from the Pribilofs. (The fre- 
quency index represents the actual number of residue 
occurrences as a proportion of the possible occurrences, 
computed as shown in footnote c of Table 2.) Detectable 
residues also were more frequent in eggs from the Gulf of 
Alaska colonies (0.547) than in all regions combined 
(0.540). Frequency of residues was lowest in eggs from the 
Seward Peninsula (0.477). 
Residues of DDE were detected in every egg we ana- 
lyzed. The frequency of DDD was relatively high in eggs 
from the Seward Peninsula (Table 2), and it was found in 
more than 60% of the eggs (all species combined) at six 
widely separated sites divided among three regions. It was 
not detected in samples from Amalik Bay (Gulf of Alaska) 
and Round Island (Bristol Bay). Residues of DDT were 
not detected in Seward Peninsula samples; they were 
found most frequently in eggs from the Pribilof Islands. 
DDT occurred in more than 40 % of the eggs from Middle- 
ton Island, the Barren Islands, and Semidi Islands (Gulf of 
Alaska); Buldir Island (Aleutian Islands); and St. George 
Island (Pribilofs), but it was not detected in any of the 
samples from Attu Island (Aleutians), Round Island, St. 
Paul Island (Pribilofs), or the Bluff Seabird Cliffs or King 
Island (Seward Peninsula). The difference in frequency of 
DDD and DDT in samples from the Pribilof Islands of St. 
George (88% and 94%) and St. Paul (56% and 0%) was 
readily apparent. 
Dieldrin, mirex, and cis-nonachlor occurred most often 
in the samples from Bristol Bay (Table 2). Dieldrin was 
detected in 90% of the total samples from Bogoslof Island 
(Aleutians) and Shaiak Island (Bristol Bay) and in all 
samples from the Barren Islands, Amalik Bay, Attu Island, 
—-and- Round-Island. It was detected in at least 15% of the 
samples from every site at which eggs were collected. 
Mirex occurred in more than 35 % of the samples from five 
sites, but was not detected in any of the samples from 
Middleton Island, Amalik Bay, Attu Island, or St. Paul Is- 
land. Cis-nonachlor was found in at least 40% of the eggs 
from six sites, and in at least 10% of those from all others 
except Attu Island, where it was not detected. 
Heptachlor epoxide was found in more than 80% of the 
eggs from Hinchinbrook Island (Gulf of Alaska) and St. 
George Island, and in about 70% of those from six other 
sites (Table 2). The lowest frequency was in samples from 
the Copper River Delta (Gulf of Alaska). 
Oxychlordane was detected in all of the eggs from the 
Pribilof Islands and Seward Peninsula, but the frequency 
of cis-chlordane in those samples was lower than the over- 
all average for this chemical (Table 2). Oxychlordane was 
detected in every sample from three widely separated sites 
(Hinchinbrook Island, Barren Islands, and Attu Island; 
Table 2), and in those from the Pribilof Islands (St. George 
and St. Paul islands) or Seward Peninsula (Bluff Seabird 
Cliffs, King Island). The lowest frequency was in eggs 
from the Copper River Delta. Cis-chlordane occurred in 
at least 60% of the eggs from six sites, all of which are in 
the Gulf of Alaska and Aleutian Islands (Table 2). Round 
Island was the only site at which it was not detected in any 
samples. 
Residues of HCB were less common in eggs from the 
Gulf of Alaska than the overall average for all regions 
combined (Table 2). However, HCB was detected in all of 
the eggs from the Pribilof Islands and Seward Peninsula. 
HCB occurred in all of the samples from Attu Island and 
in all of those from the two sites in the Pribilof Islands and 
the two in Seward Peninsula. 
The frequency of toxaphene was highest in samples 
from the Pribilof Islands and the Aleutian Islands (Table 2). 
Toxaphene was found in more than 40% of the eggs from 
seven sites. It was not detected at seven others. 
Endrin was found only in one egg of black-legged kitti- 
wake from Middleton Island (Appendix III). PCB’s were 
found in all of the samples we analyzed except for five of 
the glaucous-winged gull eggs from the Copper River Delta. 
In certain species, the frequency of residue occurrence 
by regions was substantially different from the overall pat- 
tern for all species combined (Table 3). For example, the 
frequencies of mirex in glaucous-winged gull eggs from the 
Aleutian Islands (100%) was much higher than in those 
from the Gulf of Alaska (16.8% ); for all species combined, 
the frequency of mirex was about the same in these two re- 
gions. The pattern was the same for oxychlordane, but the 
differences were not as great. Although only three clutches 
of eggs of black-legged kittiwake were collected in the 
Aleutian Islands, the frequency of most chemicals in the 
eggs that were analyzed was usually higher (often 100%) 
than in eggs from other regions. In the common murre, 
unlike most other species, the frequency of organochlorines 
in eggs from the Aleutian Islands and Bristol Bay was less 
than in eggs from the Seward Peninsula. In thick-billed 
murres, the frequency of residues was higher in eggs from 
the Seward Peninsula than in those from the Gulf of 
Alaska or the Aleutian Islands. 
Among the individual sites with two or more species 
represented, the frequency of organochlorine residue oc- 
