. The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder . 20 30 40 50 n 1 1 1 r- 10 20 30 40 50 I J ^ I I I I 10 20 30 40 50 % of pollock found in sample Figure 38-1. Changes in size of walleye pollock (Theragra chalcogramma) taken by Black-legged Kittiwakes on the Pribilof Islands. smaller clutches (p. 267), and had lower chick sur- vival (p. 262). Thus, although Black-legged Kitti- wakes may take a great variety of foods, there may be some important restrictions on the types of foods they must have if they are to reproduce suc- cessfully. Bid
. The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder . 20 30 40 50 n 1 1 1 r- 10 20 30 40 50 I J ^ I I I I 10 20 30 40 50 % of pollock found in sample Figure 38-1. Changes in size of walleye pollock (Theragra chalcogramma) taken by Black-legged Kittiwakes on the Pribilof Islands. smaller clutches (p. 267), and had lower chick sur- vival (p. 262). Thus, although Black-legged Kitti- wakes may take a great variety of foods, there may be some important restrictions on the types of foods they must have if they are to reproduce suc- cessfully. Biderman et al. (1978) and Drury and Biderman (1978) provide qualitative information on Black- legged Kittiwake foraging in the Bering Strait and along the south side of the Seward Peninsula. At Little Diomede Island, Black-legged Kittiwakes rarely foraged near land until late June, when large flocks (4,000-8,000) foraged over a shallow bar, presumably on Crustacea. Nearshore melees of foraging kitti- wakes were also seen near Bluff on the Seward Penin- sula. Foraging patterns there suggest a seasonal change in food habits similar to that seen in the Prib- ilofs. In early and mid-June, small fish were taken; in July, Crustacea seemed to be the principal prey. In August, prey fed to Black-legged Kittiwake chicks were small (3-5 cm) sand lance (Ammodytes sp.). The availability of abundant shoals of these fish may be critical to kittiwake reproductive success in the north- em Bering Sea (Drury and Biderman 1978, Ramsdell and Drury 1979). At Cape Thompson, Swartz obtained samples from both Black-legged Kittiwake adults and chicks (Table 38-5); he did not specify whether adult foods were sampled before or during the chick phase. Fish were clearly most important to this population, particu- larly sand lance and Arctic cod (Boreogadus saida), which appear to replace walleye pollock at this high latitude. Significantly more invertebrates were taken at Cape Thompson than in the Pribilofs,
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