Phalacrocorax capillatus as a breeding bird on Iwate coast, Honshiu
1967 Volume 5 Issue 1 Pages 48-60_4
Details
1967 Volume 5 Issue 1 Pages 48-60_4
1. First detailed observation on the breeding biology of Phalacrocorax capillatus has been made by the author chiefly in 1962 and 1963. About 1, 000 photographs, taken using 750mm astronomical telescope from a distance of about 100 meters, were analysed.
2. The breeding colonies were on the top of coastal rocky islands, about 60m in height, which could be observed only from a cliff point of mainland of the same height, difficult to access.
3. The arrival to the colony, in April, is irregular and if the former site were found disturbed by man, other place is selected, although the same colony has been used for some years under predation by sea-eagle Haliaeetus albicilla. Thus the shift of colony site by year was not unusual, and the disturbance by man during a breeding season seems to cause the shift in the next year.
4. Nest material is collected from nearby and the amount of nest-pile differed by site. Nest may be completed in about 10 days but material is brought in by male until after laying.
5. Clutch size was unclear, and it might be that eggs are covered by material on leaving, since eggs were shown in no photograph. Change of incubation was made after a short ceremony and is initiated by returned bird, but in other cases, the latter (male ?) fed the sitting bird and remained standing nearby. The female usually has more white neck plumes and the male broader black area around the bare face.
6. Incubation period was estimated as 34 days based on various photograph series of the same pair. The brood size was 3 in all cases observed.
7. Usual feeding method by both parents is described and their ceremonial behaviour was still observed during this period. On one hot day, a parent was observed to disgorge water which was poured on the chicks: two times per chick, the parent returning with water four times with the intervals of 5 minutes.
8. Chicks may move out of the nest by about 40 days. In this period a returned parent pretended to feed the begging chick and flew off, but the chick did not follow. A chick was observed to flap down possibly to the water and after the flying of chicks no family bond was confirmed, each individual acting entirely at their will.
9. The growth of chicks is described by stages, their plumage is totally black first and becomes white below later.
