Abstract
The National Science Museum's project of biological field survey for 1967 included the avifaunal investigation of Mt. Hayachine in Iwate of which no report is published yet. The author was appointed to this and made field studies during 29 June and 4 July.
The mountain, 1913m at the summit, is the highest peak of the east-west ridge. The north side foot zone is at the elevation of 600m of altitude, ascending as an extensive gradual and then steeper slope, grading from the oak zone, mixed desciduous forest, needle-leaved forest, dwarf forest, Pinus pumila to rocky zones. The south side is very abrupt near the summit and beech forest is developed on the foot zone, the lower part merging to the oak zone with some deforested parts down to 500m of altitude.
Bird censuses by line transect method were made on both sides, except for the steep upper south slope (owing to rainy days) and a comparative avifaunal analyses were made. Forty four species, 42 on the north side, 28 on the south side, were recorded, and 8 species were added to Mr. Kuzu's unpublished bird list which includes winter birds. These make an total of 85 species recorded from this mountain.
The north side avifauna shows a fine vertical distribution of bird species according to the forest types and was richer than on the south side where upper vertical forest divisions were lacking. The results are compared in tables and relative densities were calculated by number of birds per 1km, 1 ha, (also 40 ha for total) and 1 hour. For calculation, the highest number recorded for a same route was used, except for density per hour in which the total of numbers recorded in total census time was used. Breeding pair density was calculated for several species recorded by territory songs. Some discussions are given on factors influencing the census records. The efficiency was much better in some morning and with slow pace censuses than those of afternoon or with faster pace.
Only a few birds were collected for food analysis, and a wren specimen was so distinctly darker and fully barred as to be readily distinguished from typical Honshu birds. The observation of a Turdus pallidus suggests its possible breeding unreported from Honshu. These points are left for future.
