Feeding ecology and body size dependence on diet of the Sooty Shearwater, Puffinus griseus, in the North Pacific

The diet of the Sooty Shearwater (Puffinus gnseus) was examined by using a total of 1139 stomachs of the bird sampled during April-October, 1982, 1985-1989. Of all stomachs, 586 were empty. Predominant prey species was the Japanese sardine (Sardmops melanostictd), the wet weight percentage of which was 57.9% in the Confluence Zone, April-May, and 55.8% in the Subarctic Current, June-September. Other identified prey species were the Pacific saury (Cololabis saira), squid (Berryteuthis anonychus), pelagic barnacle (Lepas fasciculans), and jellyfish (Vellela laid). In the Subtropical Zone, June-July and the Transition Domain, June-October, the relative importance of squid and pelagic barnacle as prey items for the bird increased in both frequency of occurrence and weight. The importance of fish in the diet increased with body weight increment of the bird, while that of squid and barnacle decreased. This trend was remarkably observed in the Subtropical Zone and the Transition Domain. It is, therefore, suggested that the diet of the bird changes with their growth

Evaluation of bill furrows as age indicator in the Tufted Puffin Lunda cirrhata

Tufted Puffins (Lunda cirrhata) were divided into six stages (F(Y), F(0)-F(4)) according to the number of bill furrows formed in the reddish outer part of the upper bill. To clarify the morphological difference between sexes and among stages, eleven morphological measurements of the bills were made. Males were significantly larger than females in most of the measurements. For example, if Tufted Puffins had a gape length longer than 44.0mm there was a 72.5 percent chance that these birds would be male. The variations of these measurements among the six stages of bill furrows were recognized to have three patterns; two measurements along the gape did not vary despite the stages, five measurements, two of which were connected with lower bill, found to be changed between F(Y) and F(0), and four measurements in terms of upper bill were found to be altered between F(Y) and F(0), and F(2) and F(3). The number of bill furrows of the Tufted Puffin corresponded to six age groups on the analogy of the relationship reported between the number of bill furrows and the age in the Atlantic Puffin (Fratercula arctica) (A. PETERSEN : Ornis Scand., 7,185,1976; M. P. HARRIS : Br. Birds, 74,246,1981). The bill furrows of F(Y), F(0), F(1), F(2), and F(3) and F(4) would correspond to the age of 0 to 1,1 to 2,2 to 3,3 to 4,and 5 or older, respectively

The occurrence of Mottled Petrels in the Bering Sea

We summarized seabird census data from five research cruises, 1979 to 1985,in order to clarify the distribution of Mottled Petrels (Pterodroma inexpectata) in the Bering Sea. The northward incursion of Mottled Petrels into the Bering Sea occurred during the period from late June to mid-July. Most petrels were restricted to the central Aleutian Basin, where surface water temperatures were about 5.0-10.9℃. The number of Mottled Petrels in the Bering Sea was estimated to be about 1500000 birds