中標津町におけるショウドウツバメのコロニーの個体数推定

抄録

Sand Martins Riparia riparia ijimae were banded at Nakashibetus (43°32′N, 144°54′), eastern Hokkaido, in June and August, 1992. 312 birds captured in June were adults. Of 115 birds captured in August, all but one were juveniles. This suggests that adults leave the colony just after breeding, while juveniles remain longer.
The population size of breeding adults, estimated by Petersen's method, was 1,259 on June 22. This indicates that about 630 pairs were breeding at this colony, and that an estimated 66% of the nest holes were being utilized. These results were checked by a direct survey of nest holes after breeding was over. This showed that about 60% of the holes (28-53cm in depth), had been utilized. This figure agrees well with the estimated percentage of active nest holes, 66%.