著者

蝋山 朋雄

出版者

The Ornithological Society of Japan

雑誌

鳥 (ISSN:00409480)

巻号頁・発行日

vol.15, no.71, pp.40-44, 1958-09-30 (Released:2009-02-26)

参考文献数

5

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Many studies on the spatial distribution of insect populations have been made by various workers. But in bird populations as well as other higher animals it is not easy to determine their spatial distribution by fitting them to a theoretical distribution. The territory mapping method, however, makes this possible.If all individual birds seen or heard in a sample area are plotted on a map and several census trips are repeatedly made, number of groups of spots which indicate the location of the individuals and their territories will appear on a composite map. If the population density is so high that the territories are distributed all over the sample area, Neyman's type A contageous distribution with two parameters theoretically seem to realize in the spatial distribution of these spots. The observed distribu-tion obtained with respect to Emberiza spodocephala and Anthus hodgsoni apparently fitted the theoretical one.The mean area occupied by a group of spots which is equivalent to the mean size of a territory was obtained by calculating one of the three biological constants of Neyman's type A distribution.When, again, the population density is high and, accordingly, the distance between the nearest neighbouring territories is very short, the distribution of the territories in a sample area will be expected to be even, not random. This expectation was justified by the fact that the Poisson index of dispersion in the distribution of the geometrical centres of territories was always smaller than 1. The index, however, was not always significantly different from 1. This means that the distribution of territories in high population density would be essentially even, but, in some cases, the Poisson type apparently appeared as a result of unevenness of the environment which probably disturbed the even distribution of the territories.