Abstract
(1) Field observations of the Oriental Greenfinch, Carduelis sinica, were made from 1972 through 1977 at Momoyama Mausolea (34°56′N, 135°47′E), Ogura, and their surrounding areas (about 30 km2) in Kyoto Prefecture. The birds are resident in the study areas and breed along the edge of forests. During August and September they move from the breeding area to the place of summer concentration. Three concentrating areas were found in the study areas.
(2) These summer concentration areas were always located outside the breeding area and without exception they were adjoined by both a reed bed and a land development area covered with abundant weeds. The reed bed was used as roosting and resting site, whereas the nearby land development area supplied food. The land development area used as feeding site was situated within the range of 1 km from the reed bed where the birds roosted in concentration.
(3) Observations of ringed birds have shown that the adults leave their breeding area in early July when the juveniles of the last brood become independent. They stay at the summer concentration area until early October and then return to the breeding area. On the other hand, juveniles occurred within 2.5 km from forests in any suitable place where food was available. In July some of them concentratedd at area m, and then most of these juveniles moved to the summer concentration area p in late August and returned to the breeding area in early or middle October.
(4) Of the birds gathering at a summer concentration area, 86% of adults were from the breeding areas within 3 km from the concentration area, whereas most juveniles were from more distant breeding areas. In October, 95% of adults returned to the area where they bred in the preceeding season, while most juveniles dispersed over the wide area. Of the adults whose summer concentration area was known for two successive years, 95% of them gathered at the same concentration area. It was, however, only 67% with juveniles.
(5) The sequence of moult in both juvenile and adult was described. The juveniles that fledged before late April started the post juvenile moult of non-flight feathers (body feathers and wing-coverts) about 30 days after fledging. They ceased, however, to moult in June and started again in late July. Those that fledged after mid-May did not moult until late July. The moult of flight feathers did not start until mid-July even for those that fledged very early. In adults, the post-nuptial moult of flight and non-flight feathers started in early July.
(6) The timing and duration of moult were examined by 'regression analyses' (NEWTON, 1966) of primary moult. The complete post-nuptial moult of adults, started in early July and lasted for 90 days. Complete post juvenile moult was found in 27% of juveniles, whereas the moult was incomplete (especially primary coverts were retained) in the rest of the juveniles. The primary moult of juveniles started one to three weeks later than that of adults and lasted for 90-94 days.
(7) It was evident that adults started their post-nuptial moult as they left their breeding area and completed it by the time they returned to their breeding area. The juveniles showed some delay both in the time of concentration and of return corresponding to their delay in moult. 'aggedness values' (Haukioja, 1971a) and actual observations of fligt indicate that the flight ability of Japanes Greenfinches reduces in the period from middle August to late September in adults and that from late August to early October in juveniles.During that period both adults and juveniles showed a marked sedentary tendency at summer concentration areas.
(8) From these observations it was argued that the local concentration of Japanese Greenfinches in moult season is closely correlated with the reduction of their flight ability.
