Japanese Journal of Ornithology
Online ISSN : 1881-9710
Print ISSN : 0913-400X
ISSN-L : 0913-400X
Volume 45, Issue 2
Displaying 1-6 of 6 articles from this issue
  • Masahiko NAKAMURA, Yoshiyuki MATSUZAKI, Hiroaki OOTAKA
    1996 Volume 45 Issue 2 Pages 71-82,119
    Published: September 25, 1996
    Released on J-STAGE: September 28, 2007
    JOURNAL FREE ACCESS
    The breeding unit of the Alpine Accentor Prunella collaris is a territorial group consisting of seven unrelated members. Within the group, cooperative polygynandry is common; females copulate with several male members and the males help to feed the chicks of the several females with whom they have copulated. Do Alpine Accentors, like typical cooperative breeders, maintain the membership of the group throughout the year? The social unit in winter and the wintering ecology were studied at Ashio in 1989-95, Yoshino in 1990-93 and Misaka-Pass in 1992-95. At each site, one or two (total of four) individuals banded at a breeding site, Mt. Norikura, wintered. They exhibited wintering site fidelity within seasons and between years. They were recorded singly or in flocks with less than ten unhanded birds. The unhanded birds were not members of their breeding group, which means that the breeding group was broken' up in winter. We also found no evidence of extended bonds between parents and their offspring in winter flocks. Flocks were less cohesive and their membership often changed day by day. Linear dominance hierarchies were observed within a flock. Individual activities were concentrated in particular areas, but they frequently associated with other conspecifics without aggression. Wintering individuals spent, on average, 78.1% and 17.3% of their total activity foraging and perching, respectively. Information at other wintering sites also shows that Alpine Accentors live in less cohesive small flocks but can readily switch from solitary living to flocking. We conclude that the breeding group and the winter flock in Alpine Accentors are independent of each other because there was no evidence that individual associations (group composition and family bonds) were maintained between breeding and, wintering sites.
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  • Masami HASEGAWA, Masahiko ASADA, Kumi TANIGUCHI, Hiroyuki KURONO
    1996 Volume 45 Issue 2 Pages 83-89
    Published: September 25, 1996
    Released on J-STAGE: September 28, 2007
    JOURNAL FREE ACCESS
    Population of the Gray-faced Buzzard Eagle, Butastur indicus, a top predator of the insular food webs, were surveyed on the northern Izu Islands, central Japan. In 1993-1995 breeding seasons, the home ranges of one, three and seven breeding pairs were found on To-shima (4.2 km2), Nii-jima(22.8 km2) and Kozu-shima (18.4 km2 ), respectively. No home range was found on Shikine-jima (3.7 km2), the smallest and relatively flat island. The home ranges tend to locate on the valleies of each island, and their numbers on each island increase with the area and topographic complexity.
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  • Yoshinori OHNO
    1996 Volume 45 Issue 2 Pages 91-99,121
    Published: September 25, 1996
    Released on J-STAGE: September 28, 2007
    JOURNAL FREE ACCESS
    This study investigated the effects of nesting Gray-headed Lapwings Microsarcops cinereus on the intensity of the predation by Carrion Crows Corvus corone on eggs in artificial nests at the Nabeta reclaimed land in 1990 and 1991. The survival rate of the eggs in artificial nests increased during the Gray-headed Lapwings' breeding season because of their nestdefense behavior. Among the artificial nests placed in their territory the number of survivors for 24 hours was larger during the incubating and fledging period than during the territory-making period. The number of Carrion Crows that intruded in the defendedd area during the breeding season of Gray-headed Lapwings was significantly smaller than that during the pre-breeding period. These findings suggest that the nestdefense behavior of Gray-headed Lapwings inhibits the opportunities of nest predation by Carrion Crows.
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  • Kazuhiro EGUCHI
    1996 Volume 45 Issue 2 Pages 101-107,122
    Published: September 25, 1996
    Released on J-STAGE: September 28, 2007
    JOURNAL FREE ACCESS
    A study on the nest-site preference of the Black-billed Magpie Pica pica sericea was conducted in northeastern Saga City, northern Kyushu, Japan. In first nesting, the proportion of magpie nests on utility poles was significantly greater than expected from random nesting. However, the proportion of nests on utility poles in repeat nesting decreased in comparison to first nesting. Incomplete nests occurred more frequently in trees than on utility poles, suggesting that, if they selected trees, magpies carried nest material to more locations before settling on a suitable nest site. Pairs nesting on utility poles achieved higher nesting success than those nesting in trees. The percentage of complete magpie nests on utility poles increased from 41% in 1991 to 55% in 1994. Nesting on utility poles may be among the possible reasons for the recent geographic expansion of magpies in Japan.
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  • Keisuke UEDA, Ayako YAMAOKA
    1996 Volume 45 Issue 2 Pages 109-113
    Published: September 25, 1996
    Released on J-STAGE: September 28, 2007
    JOURNAL FREE ACCESS
  • Navjot S. SODHI, Gordon F. BENNETT, Hisashi NAGATA
    1996 Volume 45 Issue 2 Pages 115-117
    Published: September 25, 1996
    Released on J-STAGE: September 28, 2007
    JOURNAL FREE ACCESS
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