山階鳥類研究所研究報告
Online ISSN : 1883-3659
Print ISSN : 0044-0183
ISSN-L : 0044-0183
都会ハシブトガラスのなわばり繁殖観察(続く)
黒田 長久
著者情報
ジャーナル フリー

1975 年 7 巻 6 号 p. 569-602

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In 1969, a pair of Jungle Crow Corvus macrorhynchos was kept under observation from later incubation period (April 13, five days before hatching) at Akasaka, Tokyo, where I lived in its breeding territory, which was about 45.83 ha, 1000m east to west (200m to west, 750m to east from nest) and 700m north to south (500m to north, 200m to south), thus oval in shape, with the nest situated near the round end. The northern (to the direction of winter roost) and eastern (toward summer roost) territorial boundaries are deliminated by big buildings of TBS television and Parliament respectively.
The territory contains apartments, buildings of various sizes, small shops and private houses, with wooded shrine of Sanno on the hill of north-east border, wooded lawn slope of Prime Minister's official residence at eastern hill, and on the central hill, two big gingko trees, one of which having crow's nest, stand high with a patch of trees. Thus, there are some greens on central and surrounding hills, between which two main roads, one with highway, run crossing at Tameike (Fig. 1).
Main buildings and other objects frequently used by crows, for resting, guarding, food storing and eating places, are numbered on territory map, with distance lines of 50m mesh (Fig. 3) and circles (Fig. 2).
Observations were made on the roof of my home about 40m apart from the nesting gingko tree and I could see all directions of surrounding hills, except some blind area at south western part.
Observation time, usually more than 2 hours for each observation, was selected according to its purpose of following the male's movements in its morning food search commenced as soon as he returns from flock roost to his territory before sunrise, female's attendance rate to nest and her daytime activity in relation to her mate or intruding other crows, feeding rates to chicks by male and female, food storing and hiding, roosting places, sexual and family life, as well as vocal communication.
In the present paper (part 1; to be continued), observation data from April 13 to 30 are given with some tables and figures.
1.The incbation is engaged by female only, but male may visits nest with 20-30 minutes intervals, calls her for confirmation or inviting for food, and if the male doesn't return long time from food search, the female may leave the nest in search of him, in some cases advertising herself by circling flight.
2. Although sitting on nest in the foliage, the female is very keen to outside event or for vocal communication of the male and as soon as she perceives, or notices by male's voice, other crows trespass flying over beyond territorial boundary, the female at once takes off from the nest directly flying, with attack calls, to the intruders to chase them up from below. The male is, however, usually less aggressive, or even indifferent, being occupied by his job of food search for the day (But, when he is less occupied he may lead the defense chase of intruders).
3. Finished the daytime activity of food search toward evening, the male rests on high top or antenna of building more or less 100m apart from the nest, and the female leaves the nest to pass some 15 minutes with the male preening or billing each other, and together return to nest site (to gingko tree adjacent to nesting gingko). Thus ended their activity of the day, the male leaves (with soft 'ka' of roosting signal vocal) to common flock roost about 1km from the nest site and the female gets back to the nest for her night incubation or brooding of early chicks (from 31st day after hatching the female also flew off to roost).
4. Before sunrise, the male comes back to his territory in the dark of twilight, which the female on nest at once notices by his approaching call notes, and answering to him she flies out to adjacent tree to wait his arrival.

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