Habitat selection, foraging behaviour and prey items of five species of herons were studied at an estuary in Chiba Prefecture, central Japan. The two largest species, the Grey Heron Ardea cinerea and the Great White Egret Egretta alba modesta fed mainly on the tidal flat and in the river. The three smaller species, the Intermediate Egret E.intermedia, the Little Egret E.garzetta and the Cattle Egret Bubulcus ibis fed mainly on farmland. The Great White Egret and Little Egret were habitat generalists using all types of habitat, whilst the three other species seemed to be habitat specialists. Grey Herons fed only in large bodies of water; Cattle Egrets were highly terrestrial feeders; Intermediate Egrets preferred farmlands or wet habitats but avoided both large bodies of water and dry habitats. The primary foraging behaviour of Grey Herons was Standing by which method they captured large prey. Great White Egrets adopted a Walking Slowly method as well as Standing, and they took significantly smaller prey than Grey Herons. Intermediate Egrets adopted mainly Walking Slowly, Standing and slow foraging behaviours, in contrast to Little Egrets that used Walking Quickly and very active foraging behaviours. Cattle Egrets foraged mainly by Walking Slowly, but also adopted active foraging behaviours. In their feeding ecology, the Grey Heron, Intermediate Egret and Little Egret in Japan seemed to be, respectively, ecological counterparts to the Great Blue Heron A.herodias, Little Blue Heron E. caerulea and Snowy Egret E.thula in North America. Recent population declines of the Intermediate Egret may be related to deterioration of the farmland habitats upon which this species depends.

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Fecal androgen levels of migratory reed bunting Emberiza schoeniclus and non-migratory meadow bunting Emberiza cioides males were measured by radioimmunoassay after extraction with ether.When the photoperiod conditions were changed stepwise from 10 h light/14 h darkness (LD 10:14) to LD 15:9, in the migratory reed bunting the fecal androgen contents increased significantly at LD 12:12, and these relative high levels were maintained at LD 14:10.The photoperiod conditions resulting in high fecal androgen contents were similar to those resulting in nocturnal migratory restlessness.On the other hand, no significant change was observed in the non-migratory meadow bunting.The fecal androgen content would reflect the levels circulating in the plasma, as has been reported for the Japanese Quail.It has been suggested that androgen may be an endocrine regulator of vernal migration.Thus, androgen may be involved in the control of the vernal migration in the reed bunting.

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Seasonal changes in nesting vegetation, nest height, and nest success of the Bull-headed Shrike Lanius bucephalus were studied in Hokkaido, northern Japan from 1992 to 1995.Bull-headed Shrikes nested in dwarf bamboo and vine bushes in early breeding season; however, as the season progressed they moved their nest sites to a variety of deciduous shrubs as the foliage of these nesting plants increased.Nest height gradually increased throughout the breeding season, an observation that was attributed to seasonal changes in the use of nesting vegetation types.Bullheaded Shrikes showed a seasonal change of nest sites with the progress of plant phenology, and the change decreased the probability of predation.

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Diurnal changes in number within five species of understory birds captured were investigated during three spring migratory seasons (1993-1995) in a low mountain zone in western Hokkaido. Diurnal time periods were divided into three, that is 4:00-9:00 (A), 9:00-14:00 (B) and 14:00-19:00 (C). Four species (Tarsiger cyanurus, Cettia squameiceps, C.diphone and Emberiza spodocephala) showed a significant decrease in number from A to B or C. But one species (Phylloscopus occipitalis) had no significant difference in numbers in each time period.Correlation coefficients were calculated for the relationship between the number of birds of each species captured and time period (A-B, A-C, B-C). Nine statistically significant correlations were shown between specific time periods and species (see Table 3, which also includes regression formulas) As a result, we can estimate not only the number of birds in other time periods by applying data in one time period to these regression lines, but with, even a limited amount of data obtained from captured birds we can also estimate the seasonal changes in number of migartory birds.

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[in Japanese]

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[in Japanese]

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A total of 5, 305 Proccellariiform birds were counted at the Pacific off N. E. Japan (36-41°N, 142- 152°E) during 23 days of observation from fishing vessels, July-August in 1982-1989. Calonectris leucomelas was abundant where surface water temperature ranged from 20.3 to 26.5°C from coastal water to 600 km offshore. Pterodroma longirostris was common in pelagic area (24.4-26.6°C). Pt. solandri was observed up to 39°N while Pt. externa occured up to 36°30′N.

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