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Volume 36 (1987 - 198･･･
- Issue 4 Pages 137-
- Issue 2-3 Pages 71-
- Issue 1 Pages 1-
Predecessor
Volume 36, Issue 2-3
Displaying 1-6 of 6 articles from this issue
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Yukihiko KOJIMA1987 Volume 36 Issue 2-3 Pages 71-78
Published: December 25, 1987
Released on J-STAGE: September 28, 2007
JOURNAL FREE ACCESS1) The breeding of the Grey-faced Buzzard Eagle Butastur indices was studied in a mountainious region of central Japan during 1977-1980.
2) Mean laying and hatching dates of the first egg were 29 April and 31 May, respectively. The clutch size averaged 2.7 with a range of 2-4. Hatching success was 83%.
3) The initial and final brood sizes averaged 2.5 and 2.4, respectively. The average number of fledglings per active nest was 1.9. Mean fledging date of the first young was 5 July. The length of the nestling period averaged 36 days. Fledging success was 78%.
4) Of 66 nests examined, at least 64 (97%) contained eggs, 60 (91%) contained hatchlings, and 52 (79%) produced fledglings.
5) 21% of nests failed to produce fledglings. Predation and nest collapse caused by breakage of dead branches supporting the nest were the most important factors.
6) There were no apparent differences in laying date, clutch and brood sizes, and nest success between years. This suggests a stable food supply during the study period. The rare occurrence of unhatched eggs and of nestling mortality through sibling aggression may indicate a favourable food condition in the study area.View full abstractDownload PDF (6687K) -
Frank KUHLMAN1987 Volume 36 Issue 2-3 Pages 79-86
Published: December 25, 1987
Released on J-STAGE: September 28, 2007
JOURNAL FREE ACCESSFrom spring 1975 through early summer 1987 (except for springs 1980 and 1984) a population study of the Black-eared Kite Milvus migrans was conducted on the wooded slopes immediately adjoining a residential portion of Chuo Ward, Kobe, Japan. The study area, about 4 km by 2 km, consists of a dozen roughly parallel NW-SE valleys sloping toward the city and the sea beyond it.
Observations in the non-breeding season (October to February) around sunset time revealed an uneven pattern in the number of gathering kites. A westward shift in the location of the main roosting area might have been related to competition for the roosting sites from crows, especially the Thick-billed Crow Corvus macrorynchos.
Black-eared Kite pairs built nests in 65 trees (29 of them conifers) at an average height of 10 m. Some nests were used 2-4 times, so research was conducted at 94 nests. From a high of 15 nests in 1978, the number of nests gradually decreased to a low of only 3 nests in 1987.
During the last 5 years of the study, eggs disappeared from at least 18 of the 34 nests, and a half eaten nestling was found in another nest. At most 4 fledglings were raised in the 34 nests. It is considered that predtion by the Thick-billed Crow is the major cause of nest failure and population decline of the Black-eared Kite.View full abstractDownload PDF (4709K) -
Kimiya KOGA, Satoshi SHRAISHI1987 Volume 36 Issue 2-3 Pages 87-97
Published: December 25, 1987
Released on J-STAGE: September 28, 2007
JOURNAL FREE ACCESSThe brooding and feeding behavior of the Black-eared Kite Milvus migrans was investigated in the vicinity of Wakimisaki fishing-port, stituated at the southern edge of Nagasaki Peninsula, Nagasaki Pref., in 1983 and 1984. The results obtained are summarized as follows:
1) The brooding was mainly conducted by the female, but the male also occasionally took a part of brooding during the early nestling period.
2) Both the brooding time and the brooding period were influenced by weather and microhabitat conditions around nests, and also by the developmental phase of the nestlings. The female usually ceased to brood at about 40 days after hatching, when the nestlings were feathered.
3) The female played the greater part in feeding, and most of the foods brought to the nests were composed of fish. The parents provided the nestlings with enough food for theirr demands.
4) The sibling competition was chiefly observed in the first half of the nestling period, but pieces of foods swallowed by each nestling were approximately equal in number.View full abstractDownload PDF (8925K) -
Mark A. BRAZIL1987 Volume 36 Issue 2-3 Pages 99
Published: December 25, 1987
Released on J-STAGE: September 28, 2007
JOURNAL FREE ACCESS -
Mark A. BRAZIL1987 Volume 36 Issue 2-3 Pages 100
Published: December 25, 1987
Released on J-STAGE: September 28, 2007
JOURNAL FREE ACCESS -
Yuzo FUJIMAKI1987 Volume 36 Issue 2-3 Pages 101-103
Published: December 25, 1987
Released on J-STAGE: September 28, 2007
JOURNAL FREE ACCESSDuring the period between 1968 and 1987 there were 27 records of Nyctea scandiaca from Hokkaido, northerhmost island of Japan. Some of them were observed in summers. More birds were recorded in 1977 and 1983-84 than in other years. In 198344 more owls wintered also in Kamchatska. These facts suggest that a part of owls wintering in Kamchatska and Hokkaido in 1983-84 remained there in 1984.View full abstractDownload PDF (2721K)
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