PCB concentrations were significantly correlated with 
those of DDE in practically all groups. The PCB concen- 
trations, however, exceeded the DDE concentrations in all 
species by a factor that varied from 2.7 in murres to 7.8 for 
kittiwakes. 
Food of Species Samples 
Differing food of the species we sampled may account 
for some of the differences in residue concentrations. Ain- 
ley and Sanger (1979) reviewed the literature published 
through early 1975 on diets of seabirds of the northeastern 
North Pacific Ocean and Bering Sea, and diets of several 
species have been studied more recently at certain sites 
within the region. We briefly summarize here what is 
known about food in relation to organochlorine contami- 
nants for the principal species in our study. Information is 
often based on food brought to the chicks before they 
fledge, but some adults and winter specimens have been 
collected for study. Most seabirds feed as secondary and 
tertiary carnivores and eat more than one type of prey 
(Ainley and Sanger 1979). The major prey species for most 
seabirds vary by season and location, but there is little in- 
formation about the diets of seabirds while they are 
nomadic (Shuntov 1972). 
Northern Fulmar and Storm-petrels 
The northern fulmar and fork-tailed and Leach’s storm- 
petrels appear to be medium-sized and small surface-feed- 
ing generalists (opportunists) that eat whatever they can 
find (Palmer 1962; Ainley and Sanger 1979). They are 
principally secondary and tertiary carnivores and scaven- 
gers, feeding over outer portions of the continental shelf 
and in oceanic waters beyond. Typical foods include live 
and dead fish, squid, coelenterates, crustaceans (especially 
Euphausiidae), other organisms, and floating oil or 
blubber from wounded or dead marine mammals. Pearce 
et al. (1979) suggested that eggs of Leach’s storm-petrel 
from eastern Canada contained high concentrations of 
organochlorines because petrels feed at the interface of the 
air and water where these chemicals first reach the oceans 
and where they may be held on the surface by a thin oily 
film. 
Cormorants 
Cormorants are secondary and tertiary carnivores and 
feed relatively close to shore (Ainley and Sanger 1979). 
Double-crested cormorants are primarily piscivorous, 
feeding particularly on schooling fishes that occur at 
moderate to great depths. Pelagic and red-faced cor- 
morants feed more heavily on benthic fish and decapod 
crustaceans (see also Palmer 1962 and Hunt 1977). 
Glaucous-winged Gull 
Glaucous-winged gulls are secondary, tertiary, and 
upper-level carnivores and scavengers in nearshore habi- 
21 
tats (Ainley and Sanger 1979). This species, like other 
gulls, is an omnivorous opportunist (Trapp 1979). At four 
locations in the western Aleutian Islands glaucous-winged 
gulls fed on a large variety of organisms, but at any given 
site they specialized on the species that were most abun- 
dant and vulnerable. Inter-island differences in diet 
seemed related to island physiography, the available food 
source, and the effects of sea otters (Enhydra lutris) on the 
structure of the nearshore community. At Alaid-Nizki and 
Agattu, glaucous-winged gulls fed primarily on intertidal 
invertebrates; at Buldir and Semisopochnoi the principal 
food was birds; and at Little Kiska the primary prey was 
fish, Glaucous-winged gulls have also been observed eat- 
ing the eggs and young of murres at Bogoslof Island 
(Gabrielson and Lincoln 1959: Murie 1959; G. V. Byrd, 
personal communication cited in Trapp 1979). (However, 
at certain times they feed heavily on walleye pollock 
[ Theragra chalcogramma] at Bogoslof Island, as observed 
by G. J. Divoky and G. V. Byrd [unpublished data].) 
These locality differences — particularly the high propor- 
tion of birds in the diet of gulls at Buldir and Bogoslof 
islands— may account for the higher concentrations of 
organochlorine residues in gull eggs from those sites. 
Moe and Day (1979) reported that in the Shumagin Is- 
lands, birds (or their eggs) and marine invertebrates 
(mainly intertidal) were the predominant items in food 
pellets regurgitated by glaucous-winged gulls. These 
authors believed that fish might have been under-repre- 
sented in the pellets because they were more readily di- 
gested and therefore not cast in pellets. 
At Kodiak Island, glaucous-winged gulls ate a greater 
variety of prey than did black-legged kittiwakes or tufted 
puffins (Baird and Hatch 1979). Capelin (Mallotus villo- 
sus) and Pacific sand lance (Ammodytes hexapterus) were 
predominant prey species, and their relative abundance in 
the area apparently was reflected in the diet. At 
Ugaiushak Island, glaucous-winged gulls fed primarily on 
sand lance in July and August in 1977 (Wehle 1978). 
Black-legged Kittiwake 
Black-legged kittiwakes evidently feed opportunisti- 
cally, but become specialists if suitable prey is abundant 
(Drury 1978). Kittiwakes feed at or near the surface; their 
food varies among the regions of Alaska where studies 
have been conducted. 
In the northwestern Gulf of Alaska, kittiwakes are pri- 
marily piscivorous. At Kodiak Island they feed heavily on 
capelin early in the summer, but sand lance replace cape- 
lin as the principal food before the young have fledged 
(Baird and Moe 1978; Sanger et al. 1978a, 1978b; Baird 
and Hatch 1979; Krasnow et al. 1979). Euphausiid crus- 
taceans (especially Thysanoessa inermis) are important 
prey early in the nesting seasons. At Middleton Island, fish 
(predominantly sand lance) composed almost 80% of the 
diet in 1978 (Hatch et al. 1979); euphausiids made up most 
