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

Bioaccumulation and metabolism of PCBs and DDE in Short-tailed Shearwater Puffinus tenuirostris during its transequatorial migration and in the wintering and breeding grounds

PCBs and p, p\u27-DDE in Short-tailed Shearwater (Puffinus tenuirostris) from Tasmania, Japan and the northern North Pacific were measured. The mean concentrations of PCBs and p, p\u27-DDE found in the bind from Tasmania were 14 and 20ng/g in chicks and 150 and 89ng/g in adults respectively, on wet weight basis. The values of both the chemicals were found to be lower in chicks than in adults, and the degree of disparity in chemical levels between chicks and adults is greater in PCBs than in p, p\u27-DDE. Reflecting this, the DDE/PCB ratios were higher in chicks (1.3) than in adults (0.60). This is likely due to the greater accumulation of PCBs during the period of stay in the northern North Pacific feeding ground than in the southern South Pacific ones. The shearwaters from Japan and the northern North Pacific seem to be post-fledgling or yearlings, since their DDE/PCB ratios (1.1 and 1.2) were found to be nearly the same as those in chicks (1.3) from Tasmania. It is known that two types of metabolic enzymes (PB and MC type) are mainly associated with the PCB metabolism in higher animals. When compared the PCB compositions in the shearwaters from Japan and Tasmania, some members of PCBs metabolized mainly by the MC type enzyme systems were found to decrease or disappear in the bird from Japan, indicating that the activity of the MC type enzyme systems in the shearwater increased more than that of the PB type enzyme systems during the transequatorial migration of the bird