Ecological study of the bird community of the broad-leaved deciduous forest of central Japan

抄録

1. The ecological survey of a breeding bird community was carried out in the broad-leaved deciduous forest of Chichibu-Tama National Park in central Japan, and the food consumption of each species population was estimated by a procedure based on the feeding experiments of captive birds.
2. The feeding experiments were carried out on Uroloncha domestica, Cyanopica cyanus japonica and Corvus corone orientalis. The food intake was 2.7 and 2.4gm dry weight per bird per day or 11.1 and 9.8 Kcal per bird per day in female and male Uroloncha, respectively, fed on great millet. It was 11.8 and 15.2gm dry weight per bird per day or 57.2 and 72.8 Kcal per bird per day in Cyanopica fed on a paste food and sikworm, respectively. Corvus fed on horse-mackerel consumed the food averaging 38.2gm dry weight per bird per day or 221.4 Kcal per bird per day.
3. The faeces output was 0.34 and 0.31gm dry weight per bird per day or 1.18 and 1.08 Kcal per bird per day in female and male Uroloncha, 7.18 and 4.25gm dry weight per bird per day or 27.02 and 14.51 Kcal per bird per day in Cyanopica fed on a paste food and sikworms, and 15.3gm dry weight per bird per day or 41.4 Kcal per bird per day in Corvus.
4. The interspecific comparison of digestible energy was made on available data, and the relation between digestible energy and body weight was discussed. It was suggested that the logarithm of digestible energy was roughly proportional to the logarithm of body weight according to the equation Y=2.03W^0.706.
5. The digestive coefficient of various food organisms was also compared and some discusssions were made.
6. The available data on the food consumption of the wild birds were examined with respect to that of captive birds and the relation between food intake and body weight.
7. The breeding bird census was carried out by the method of territory mapping on a belt-shaped plot, which was 2750m long, in 1957 and 1958.
8. Number of species was 28 in 1957 and 29 in 1958. The total density was 505+ pairs per square km in 1957 and 636+ pairs per square km in 1958. The most abundant species was Erithacus cyane, followed by Parus major, Phylloscopus occipitalis and Parus ater (only in 1958).
9. The total biomass was about 45kg per square km in both years, much higher than that of similar forest of eastern North America.
10. The pattern of distribution corresponding with the pattern of physiographic and/or vegetational feature of the habitat in the census area was seen in some species.
11. Accoriding to the feeding niches observed, 26 species were divided into 7 or 8 feeding groups, and the feeding niches of some species were described in some details.
12. The food consumption of every species population in the forest was calculated on the several assumptions. The group which consumed the food organisms most abundantly was "Ground" group and those species that consumed the food much more than others were Phasianus soemmerringii, Erithacus cyane and Garrulus glandarius.
13. Some discussions based on these calculated values were made.