It is commonly thought that Tree Sparrow Passer montanus numbers have decreased in Japan in recent decades. Here, in order to ascertain this surmise, the population decline in the last several decades was estimated based on published articles and data. The analysis shows that the overall population has fallen by at least half since 1990 and by more than 90% since the 1960s. These results indicate the necessity of monitoring and managing this once abundant species in Japan.

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Immigration and flight patterns of the Great Cormorant Phalacrocorax carbo, which migrates widely from large coastal colonies to inland areas, were investigated using detection records of banded individuals in Yamanashi Prefecture, central Japan. A total of 13 banded individuals (eight individuals recovered following shooting; two by hooking; three by resighting) were detected between 2003 and 2008. In the Fuji River basin, an estuary located in Suruga Bay, all five individuals originated in Aichi and Shiga Prefectures. In contrast, in the Sagami and Tama River basins, estuaries located in Sagami and Tokyo Bay, respectively, all eight banded individuals originated in the Metropolis of Tokyo and in Chiba Prefecture. The original banding locations were separated by river basins. In the Fuji River basin, cormorants immigrating or passing through originated in the Chubu and Kinki Regions, whereas in the Sagami and Tama River basins, cormorants originated in the Kanto Region. In Yamanashi Prefecture, as well as in other areas where cormorant banding has never been conducted, existing data on captured (i.e., shot) cormorants should be used to examine migration habits, similar to this study. This approach would allow a more thorough understanding of cormorant migratory patterns through the integration of detection records for banded individuals throughout Japan.

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The range of the Brown-eared Bulbul Hypsipetes amaurotis is mostly restricted to Japan and adjacent areas of East Asia. Although bulbuls are very common, no attempt has previously been made to estimate the numbers or density of bulbuls in Japan. We investigated the distribution of bulbul song-posts in southern Ibaraki Prefecture (648 km²) and with that information estimated their population density. We set 32 survey grids (1 km×1 km) in the study area and confirmed a total of 540 bulbul song-posts during the 2007 breeding season. We then estimated the breeding density of bulbuls with the Poisson regression using a variety of environmental factors. Factors positively influencing breeding density were: the area ratios of ‘forest’, ‘dry-cropland or grassland’ and ‘urban area’. Considering that bulbuls are monogamous and only males sing, we estimated there to be a total of 24,634 breeding bulbuls in the study area and a mean of 38 breeding individuals within 1 km². We then classified the study area into five categories with the cluster analysis based on the proportion of land use within each 1 km grid. The clusters with the highest breeding densities of bulbuls were: (1) forest, (2) urban and (3) dry-cropland or grassland. Because small woodlands are also found in urban areas and dry-croplands or grasslands occur in the study area, our results indicate that the presence of woodlands is important in habitat selection by bulbuls in the breeding season.

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In order to identify the frugivorous bird species with the potential to disperse the seeds of broad-leaved trees and herbaceous plants into conifer plantations, we caught birds with mist nets and sampled their faeces in a Japanese cedar Cryptomeria japonica plantation and neighbouring areas in southern Kyushu, Japan. In the autumn-winter period, intact seeds of six broad-leaved tree species and one herbaceous plant species were recovered from the faeces of nine individuals of five frugivorous bird species: seeds of Maesa japonica and Rubus buergeri from the faeces of the Red-flanked Bluetail Tarsiger cyanurus; Eurya japonica, Callicarpa japonica and the herbaceous plant Tubocapsicum anomalum from the faeces of the Pale Thrush Turudus pallidus, E. japonica from the faeces of the Red-billed Leiothrix Leiothrix lutea, R. buergeri from the faeces of the Japanese Bush Warbler Cettia diphone, and Celastrus orbiculatus from the faeces of the Japanese White-eye Zosterops japonicus. In the spring-summer period, intact seeds of one broad-leaved tree species, Rubus palmatus var. palmatus, were recovered from the faeces of the Eurasian Jay Garrulus glandarius. It has been shown that these six frugivorous bird species at least have a role as the seed dispersers of broad-leaved trees and herbaceous plants into conifer plantations.

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We investigated telomere length of Black-tailed Gull Larus crassirostris (chick and adult) in Rishiri Island, Hokkaido and Kabushima, Aomori in relation to their age. DNAs were extracted from their bloods and detected telomere length. Telomere lengths were significantly decreased with gulls' age. But coefficient value was too small because of large variability of telomere length in both chick and adult. We suggest that it is difficult for Black-tailed Gull to estimate their age by using telomere length.

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Fishery damage caused by Great Cormorants Phalacrocorax carbo has recently become a critical issue in Japan. In our study, we identified the food habits of cormorant based on chick regurgitations, in Unoyama, Chita Peninsula, Aichi Prefecture, and from the stomach contents of legally shot cormorants at Yahagi River, Toyota, Aichi Prefecture. We examined whether the food habits of these two locations varied depending on cormorants' diet, and estimated the extent of damage to the Ayu Plecoglossus altivelis altivelis fishery based on stomach contents from the Yahagi sample, a location where concerns about Ayu fishery damage have arisen. Unoyama is located close to the coast, samples from there consisted mostly of coastal and brackish water fish species (96.5%), whereas the samples from the Yahagi River, which is located inland, were mostly composed of fluvial fish (98.5%). An index of relative importance for Ayu in the Yahagi sample ranked it 6th, and the species represented a wet weight percentage of just 5.18 %, suggesting that Ayu is relatively unimportant in the cormorant's diet. We recommend that in order to understand fishery damage by Great Cormorants it is necessary to estimate damage in each local area.

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To understand the relationship between grazing by wintering geese, the dry mass of the grass Lolium hybridum and soil inorganic nitrogen, we determined the dry mass of young shoots and their nitrogen content, and soil inorganic nitrogen from plots in grazed and un-grazed sites in April and May 2008. The mean dry biomass of un-grazed shoots was 4,500 kg/ha (N53), while that of grazed shoots was 256 kg/ha (N56). Both the nitrogen content of the grass, and the soil inorganic nitrogen, were significantly higher in the grazed site than in the un-grazed sites. It is possible that the accumulation of goose droppings caused the raised levels of soil inorganic nitrogen, which helped the grass to regenerate.

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[in Japanese]

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