
22 
of the rest of it. Kittiwakes nesting in lower Cook Inlet in 
1978 fed their chicks almost exclusively fish (Jones and 
Petersen 1979). Sand lance was the predominant prey 
species and capelin was secondary in importance. 
Kittiwakes in the southern Bering Sea have a varied diet 
and do not feed heavily on any single species. In the north- 
ern Bering Sea and Chukchi Sea, birds of different colonies 
eat different foods, but capelin is not usually an important 
prey species (Hunt 1977; Biderman et al. 1978; Divoky 
1978; Drury 1978; Springer and Roseneau 1978; Ramsdell 
and Drury 1979; Springer et al. 1979). For some colonies, 
sand lance become an important food source in early 
August while the young are still in the nest. In the north- 
ern Chukchi Sea and in Beaufort Sea, kittiwakes eat pri- 
marily arctic cod, Boreogadus saida (G. J. Divoky, unpub- 
lished data). 
Kittiwakes wintering in Monterey Bay, California, and 
which probably breed in Alaska, feed heavily on squid 
(Loligo opalescens) during the winter, but they also eat 
anchovies (Engraulis mordax) and euphausiid crustaceans 
(Morejohn et al. 1978). 
We found no apparent dietary differences in kittiwakes 
(compared with the other species we studied) that would 
account for the much higher PCB to DDE ratio we have 
reported. (As we noted previously, kittiwakes have low 
concentrations of DDE, rather than high concentrations 
of PCB’s, that cause the ratio to be higher than in other 
species.) Perhaps physiological differences or other factors, 
such as concentrations of organochlorines in their winter 
prey, may be involved. 
Murres and Puffins 
Murres and puffins feed heavily on fish, mainly species 
that school in midwater (Ainley and Sanger 1979). Like 
many other species, these birds are opportunistic, feeding 
rather heavily at times on cephalopods and crustaceans, 
particularly nektonic forms. Morphological differences 
between the two murre species suggest that thick-billed 
murres feed on benthic organisms much more than do 
common murres, and that the common murre is the more 
piscivorous (Bedard 1969; Spring 1971; see also Hunt 1977 
and Springer and Roseneau 1978). However, when the 
two murres feed together along the Bering Sea ice “front,” 
their diets are similar (Divoky 1978); both then feed pri- 
marily on walleye pollock, capelin, hyperiid amphipods 
(Parathemisto libellula), and euphausiid crustaceans that 
are among the more abundant potential prey available in 
the area. 
In the Kodiak Island area and on Ugaiushak Island, 
common murres were exclusively piscivorous and tufted 
puffins were largely so during the summer of 1977 (Sanger 
et al. 1978b; Wehle 1978). Capelin was the most impor- 
tant prey species; euphausiid crustaceans and squid were 
taken seasonally. The following year both species fed 
largely on fish in the Kodiak area; capelin and sand lance 
were the principal forage fishes for each species (Krasnow 

et al. 1979). Common murres also fed extensively on wall- 
eye pollock; fish made up 98% of the diet. 
Common murres in Kachemak Bay, Alaska, fed much 
less extensively on fish (from November 1977 to April 
1978) than they did in the Kodiak area or at other sites 
where their food has been studied (Sanger and Jones 1981), 
Crustaceans made up 84% of the diet in the Bay; shrimp 
(Pandalidae) and mysids (Neomysis rayii) were the most 
important prey. In marked contrast, fish were the most 
important prey at other locations. However, these findings 
may reflect seasonal differences in diet: in summer, 
murres are almost exclusively piscivorous in the Kodiak 
area (Sanger et al. 1978b; Krasnow et al. 1979) and in the 
Bering Sea (Hunt 1976; Ogi and Tsujita 1973). 
Thick-billed murres in the northern North Pacific 
Ocean feed primarily on squid and euphausiids (Ogi 1978). 
Squid are the most important prey, and fish are less impor- 
tant than invertebrates. 
Tufted puffins feed primarily on capelin and sand lance 
in the Kodiak area during summer (Baird and Moe 1978; 
Moe and Baird 1978; Baird and Hatch 1979). Capelin was 
the most important prey species in 1977 but the puffins ate 
more sand lance in 1978, apparently because capelin were 
less abundant. Other species of fish made up most of the 
rest of the diet, but some cephalopods (less than 5% of the 
diet) and euphausiids were eaten. 
Although tufted puffins at Middleton Island in 1978 ate 
principally sand lance, they also fed extensively on squid 
and octopus, which made up 36% of the diet (Hatch et al. 
1979). These cephalopods were probably obtained in 
deepwater foraging areas beyond the continental slope, 
some 15 to 25 km from the nesting area. 
In 1978, horned puffins nesting in lower Cook: Inlet 
apparently fed their chicks only sand lance (Jones and 
Petersen 1979). Sand lance also was the predominant food 
for horned puffin chicks in the Shumagin Islands in 1976, 
constituting 70% of the diet; capelin made up 20% (Moe 
and Day 1979). The relative importance of these two 
species shifted during the two and one-half week sampling 
period in August; consumption of sand lance increased 
and that of capelin decreased. 
Both tufted and horned puffins on Buldir Island during 
the summer of 1975 fed primarily on squid and sand lance 
(D. H. S. Wehle, personal communication). In the Barren 
Islands they both feed primarily on capelin and sand lance 
(Amaral and Manuwal 1978; Manuwal and Boersma 
1978); several other fish species compose most of the rest of 
the diet. 
Although the diets of murres (especially common 
murres) and puffins consist primarily of fish, the specific 
prey species and their relative importance in the diet 
change seasonally and geographically. Murres and puffins 
also eat invertebrates in large numbers when they are 
available. However, the diets of these birds are not known 
in sufficient detail to enable us to determine whether they 
might account for differences we found in organochlorine 
residue content in their eggs. 
