We investigated the feeding ecology of the Black-faced Spoonbill in the Yatsushiro Sea, Japan. These birds typically arrive for the winter in late October and remain until early April; however, seven young birds spent the summer of 2009 in the Yatsushiro Sea, Kyushu. As with other spoonbill species, Black-faced Spoonbills perform tactile feeding by immersing their bills in water and sweeping them from side to side. Fish, shrimps and crabs were all recognized as prey, but most prey items were too small to be identified. Tidal flat pools and streams near their loafing sites were important foraging areas. Birds used many different feeding sites during winter, but most foraged in only one river during summer. The birds ate many small prey items in marine areas whereas they ate fewer, larger prey in riverine areas. The low catch rate in riverine areas may be the result of the long handling time required for large prey. Birds may make most effective use of shallow water areas by shifting feeding sites or environments periodically. The preservation of shallow water estuarine areas close to established loafing sites is essential for the conservation of the highly restricted and endangered Black-faced Spoonbill.
We satellite-tracked Whooper Swans Cygnus cygnus wintering in northern Japan to document their migration routes and timing, and to identify breeding areas. From 47 swans that we marked at Lake Izunuma-Uchinuma, Miyagi Prefecture, northeast Honshu, and at Lake Kussharo, east Hokkaido, we observed 57 spring and 33 autumn migrations from 2009-2012. In spring, swans migrated north along Sakhalin Island from eastern Hokkaido using stopovers in Sakhalin, at the mouth of the Amur River and in northern coastal areas of the Sea of Okhotsk. They ultimately reached molting/breeding areas along the Indigirka River and the lower Kolyma River in northern Russia. In autumn, the swans basically reversed the spring migration routes. We identified northern Honshu, eastern Hokkaido, coastal areas in Sakhalin, the lower Amur River and northern coastal areas of the Sea of Okhotsk as the most frequent stopover sites, and the middle reaches of the Indigirka and the lower Kolyma River as presumed breeding sites. Our results are helpful in understanding the distribution of the breeding and stopover sites of Whooper Swans wintering in Japan and in identifying their major migration habitats. Our findings contribute to understanding the potential transmission process of avian influenza viruses potentially carried by swans, and provide information necessary to conserve Whooper Swans in East Asia.
Population fluctuations and habitat preferences of Ijima's Copper Pheasant Syrmaticus soemmerringii ijimae were investigated using a line transect method at two locations in southern Kyushu from 2002 to 2013. During the 12 years of the survey, transects were walked a total of 536 times (representing approximately 2,150 hours and a walking distance of around 3,590 km). The total number of encounters was only 127 birds, which represents one bird every 16.9 hours or 28.3 km. The number of birds encountered appeared to decrease steadily throughout the study period. The frequency of encounters was higher in evergreen and deciduous broad-leaved forests, and lower in mature cedar and cypress plantations. Therefore, it is suggested that increasing their preferred broad-leaved forest habitat would be an appropriate strategy for the recovery of the declining Ijima's Copper Pheasant population.
Many vagrant passerines from the Western Palearctic have been documented in Japan. In the present study, I tested the following two hypotheses: (1) the vagrancy of continental passerines migrating to Japan is affected by migratory distance and migratory direction, rather than distance from the normal distributional range; and (2) the vagrancy of continental passerines migrating to Japan is related to migratory restlessness. Data on vagrants were collected from various sources, and the effects of migratory distance, distance from the normal distributional range, migratory restlessness, migratory direction, and normal distribution size were examined. The results revealed significant positive effects of migratory distance and migratory restlessness, with these effects being significant even when the effects of other variables were controlled. The normal distribution size had a marginally significant positive effect, but none of the remaining variables predicted the occurrence of vagrants. The vicinity of the normal distributional range of continental passerines was not a predictor of vagrancy. These findings indicate that the endogenous migratory program of individuals is responsible for the occurrence of vagrants in Japan, and that sufficiently restless birds may reach the Far East.
The Izu Islands of Japan are a geographically young volcanic archipelago nearer to the mainland than other islands used in speciation studies, such as the Galapagos Islands of Ecuador. On the Izu Islands, birds are likely to have undergone recent colonization and trait diversification. Three morphological groups of Varied Tits, Poecile varius, breed on the islands. The varius group, which has the smallest body size and is the same as that found on the mainland, breeds on the northernmost island (closest to the mainland). The namiyei group, which has an intermediate body size, breeds on two or three central islands, and the owstoni group, which has the largest body size, is found on several southern islands. To infer the gene flow ranges and colonization processes of Varied Tits with such obvious trait polymorphisms among the Izu Islands, we analyzed the genetic population structures of these three morphological groups. In genetic analysis of all samples, individuals were first divided into cluster A, which was composed of individuals from Kohzu Island (a central island) from the namiyei group, and cluster B, which was composed of individuals from mainland sites and other islands (excluding Kohzu and Niijima). The genetic characteristics of individuals from Niijima may indicate a recent gene flow event between clusters A and B. Individuals from the owstoni group were genetically similar to varius group individuals, despite the large distance between the breeding areas of these two groups. The second step of our analysis used samples from cluster B. These samples were grouped into three clusters, one of which was further classified into two clusters in our third-step analysis. In conclusion, we detected a hierarchical structure among Varied Tits breeding on the Izu Islands and inferred that ancestors of the owstoni group colonized from the mainland more recently than those of the namiyei group.
Although avian basal metabolic rate (BMR) has been widely used in interspecific comparative studies, the sources of within-species variation in this parameter are still relatively poorly understood. Individually differing levels of activity and stress responsiveness have been proposed as potential sources for such variation in BMR. Here, I used an open flow-through respirometry system to examine the possible correlates of the time it takes individual Laughing Doves Spilopelia senegalensis to reach lowest oxygen consumption level in a metabolic chamber (‘BMR time’). Also, the association between individual response to handling stress and BMR was studied. Breath rate, measured while holding the bird in hand, was used as a measure of stress response to handling. It was found that ‘BMR time’ was not related to BMR or breath rate. However, its values were positively predicted by individuals' hematocrit. This indicates the potential importance of ‘BMR time’ as an indicator of activity. It was also found that breath rate was individually repeatable when two measurements were taken 12 hours apart. Breath rate was also positively related to BMR; however, the effect disappeared when mass-specific residuals of BMR were used. These results suggest that individual differences in response to standard handling stress probably do not affect BMR measurements.
The White-tailed Eagle breeds and winters on Hokkaido, the northern island of Japan. It is not known whether wintering eagles occasionally observed in southern Japan migrate there from the Hokkaido population or arrive from an Asian continental population. To further our understanding of their migration, we examined a nucleotide sequence of mitochondrial DNA and a multilocus genotype from the nuclear DNA of an eagle found wintering on Tsushima Island, southern Japan. Our results revealed that the eagle had originated from a continental population.