体脂質を中心とする鳥類の渡りに関する生理生態学的研究

抄録

Body weights in E. r. latifascia and A. a. orientalis increase in premigration periods. Body weights in E. r. latifascia and P. m. saturatus also increase in winter. Body weight and lipid in L. fasciolata do not differ significantly in both periods of spring and autumnal migration.
Liver weights in A. a. orientalis and E. r. latifascia increase in premigration period. Thus the high metabolism of lipid in liver appears in premigration period.
Melting point of lipids in A. a. orientalis and E. r. latifascia decrease in premigration periods which suggests the increase of unsaturated fatty acids in lipid. Iodine values in A. a. orientalis and E. r. latifascia increase in molting period and slightly decrease in premigration period. Saponification values in A. a. orientalis and E. r. latifascia gradually increase in premigration period. Saponification values in E. r. latifascia and P. m. saturatus increase in winter. The value of subcutaneous lipid in E. r. latifascia is higher than that of the body lipid, while in P. m. saturatus does not differ significantly.
Fatty acid composition of lipid in several passerine birds mainly consist of oleic acid and palmitic acid. Fatty acid composition in E. r. latifascia tends to increase in unsaturated fatty acid from midwinter to premigration period.
Food intake in caged E. r. latifascia increases in winter and becomes more intense in spring, while it increases in winter and breeding season in P. m. saturatus.
Zugunruhe in E. r. latifascia appears in late April and early May and lasts approximately one and a half month or slightly longer. The duration of Zugunruhe may not be fixed in the species, but may be changeable to the physiological and ecological conditions.
A working hypothesis can be proposed for the spring migration.