Sex and individual variations in the diet of Slaty-backed Gulls Larus schistisagus were studied on Teuri Island (44°25′N, 141°19′E), Haboro, Hokkaido, during 1984 and 1985 breeding seasons. Overall, these gulls were dietary generalists, feeding on pelagic fish, bottom-living fish wasted by fishermen, marine invertebrates, garbage and seabird chicks. However, especially individual males showed marked individual diet difference within this array of food type.
Part of the diet variation may be due to sexual differences. On average, males fed their offspring with more seabird chicks and bottom-living fish than did females. Females fed with more pelagic fish and marine invertebrates than did males, and rarely provided seabird prey. Males were larger than females. However, although relatively more variation in body size occurs between sexes than within sexes, relatively more diet variation occurs within sexes than between sexes; indicating that intrapopulation competition for food had not been a main ultimate factor contributing to sexual dimorphism.
Males preying on seabirds ('hunting-biased males') frequently took gull chicks, but others killed mostly chicks of Rhinoceros Auklets Cerorhinca monocerata. Gull chicks were more difficult prey than the auklet chicks for Slaty-backed Gulls. Cannibal hunting-biased pairs preying upon conspecific chicks also frequently killed chicks of Black-tailed Gulls L. crassirostris. This suggests basic individual difference in predatory skills among males, since different skills are required for killing gull vs. auklet chicks.

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1) Flock organization, dispersion and terriorial behaviour of the wintering Hooded Cranes Grus monacha were studied in Izumi and Akune, southwestern Kyushu from 1980 to 1984.
2) Most of the cranes spent the daytime at a feeding site adjacent to their roost, but about 10% of them flew out in the early morning and returned in the evening. All cranes gathered in two communal roosts at night.
3) A total of 83 different units (solitary birds and flocks) was observed by line censuses outside the feeding site.One solitary bird was observed(1.2%)and flocks(98.8%)ranged from two to 102birds. The flock sizes of less than ten birds in order of frequency were three(36.1%), two (16.9%), four(14.5%), six(3.6%), five(2.4%), eight(1.2%), and nine(1.2%). The two-bird flocks consisting of adults were thought to be pairs, and three-bird flocks with one juvenile and four-bird flocks with two juveniles were thought to be families. Large-size flocks consisted of solitary immature birds, solitary adults, pairs and families.
4) Territorial, resident and wandering units were observed outside the feeding site. In the territorial units, semi-territorial units which were subordinate to the neighbouring units but excluded other units, were observed. The territorial and resident units were pairs or families. The wandering units were solitary birds, pairs, families or mixed flocks. Excluding units which had hostility towards other units and little site attachment, were obserded at the feeding site.
5) Alert, threat-approaching, attacking and confronting were described as territorial behaviour. Both sexes defended their territory, while a male took the active role in direct attacks on intruders. Territory size was 54, 790 m². One territory was kept by the same flock throughout several winters.
6)Immature birds and solitary adults are thought to join the mixed flocks, forming pairs with the members of the flocks. Such pairs may leave the mixed flocks to establish their own territories.
7) The number of territorial cranes was less than 8.4%, which is thought that cranes gathered at the feeding site and did not hold territories outside the site because the food was short. However, pair and family territories are the most stable in term of efficiency in defense when they maintain territories.

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The growth and development of known-age, nine Black-eared Kite nestlings from four nests were investigated in the vicinity of the Wakimisaki fishing-port, situated at the southern edge of the Nagasaki peninsula, Nagasaki Prefecture, in 1984. The results obtained are summarized as follows.
1) The second down appeared on the body by 9-12 days after hatching, and the body feathers emerged at 18-22 days. The nestlings began standing on both legs at 17-19 days and flapping their wings at 27-31 days. They began to eat prey animals by themselves at 45-47 days.
2) Some diurnal raptors rear a young each brood (Bl species) and some others raise two or more young (B2 species). Of the four nests examined, three nests each contained two nestlings, and a nest had three. Therefore, the Black-eared kite belongs to the B2 species. At one nest the younger and elder nestlings increased their body weight at the same growth rate; at two nests the younger sibling(s) gained slower their body weight than did the elder. At the other nest, the younger chick died of starvation. Judging from the uniformity of the environmental condition in relation to food availability among the four nests, it seemed that the foraging ability of the parent kites varied with the individual and influenced the survival and growth of younger sibling(s).
3) The growth rate constant of the logistic equation fitted to weight data for each nestling averaged 0.133. This value did not differ significantly from the expected value of 0.169, which was calculated by the equation correlating the growth rate constant with the asymptotic body weight for 27 species of the B2 diurnal raptors.
4) The emergence of body feathers and the initiation of standing on both legs tended to occur at an earlier growth stage in large raptors than in small ones. In this connection, it was concluded that the Black-eared Kite, in spite of being a medium-sized raptor, possesses about the same developmental pattern as that of the large raptors rather than that of small or other medium-sized ones.

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Food storing behaviour in birds can be divided into two components: food caching behavior and food recovering behavior. In this study we investigated on the food recovering behavior of the Varied Tit Parus varius, which has a food storing habit, by using a psychological procedure of learning. Three individuals of Varied Tits from the same clutch were used for testing. After they have learned the maked place of hidden seeds, six types of tests were conducted: two tests were done.by, moving the mark place to another place.(Tost I and II), two tests by adding extra marks around the original place (Test III and IV), a test with a mark on every door (Test V), and a test without any mark (Test VI). In test I and II, 78.5% of the 144 responses were directed to the place where the mark was moved.
In Test III and IV, 97.2% of the 35 responses were directed to the places with marks. In Test V and VI, the responses were scattered to many places and no preference to the original place was observed. These results suggest that marks play an important role in Varied Tits to remember the place where food was stored.

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