Kuwae T.,Port and Airport Research Institute |
Miyoshi E.,Port and Airport Research Institute |
Hosokawa S.,Port and Airport Research Institute |
Ichimi K.,Kagawa University |
And 7 more authors.
Ecology Letters | Year: 2012
Food webs are comprised of a network of trophic interactions and are essential to elucidating ecosystem processes and functions. However, the presence of unknown, but critical networks hampers understanding of complex and dynamic food webs in nature. Here, we empirically demonstrate a missing link, both critical and variable, by revealing that direct predator-prey relationships between shorebirds and biofilm are widespread and mediated by multiple ecological and evolutionary determinants. Food source mixing models and energy budget estimates indicate that the strength of the missing linkage is dependent on predator traits (body mass and foraging action rate) and the environment that determines food density. Morphological analyses, showing that smaller bodied species possess more developed feeding apparatus to consume biofilm, suggest that the linkage is also phylogenetically dependent and affords a compelling re-interpretation of niche differentiation. We contend that exploring missing links is a necessity for revealing true network structure and dynamics. © 2012 Blackwell Publishing Ltd/CNRS.
Katayama N.,Japan National Institute for Agro - Environmental Sciences |
Amano T.,University of Cambridge |
Naoe S.,University of Tokyo |
Yamakita T.,Japan Agency for Marine - Earth Science and Technology |
And 4 more authors.
PLoS ONE | Year: 2014
The importance of landscape heterogeneity to biodiversity may depend on the size of the geographic range of species, which in turn can reflect species traits (such as habitat generalization) and the effects of historical and contemporary land covers. We used nationwide bird survey data from Japan, where heterogeneous landscapes predominate, to test the hypothesis that wide-ranging species are positively associated with landscape heterogeneity in terms of species richness and abundance, whereas narrow-ranging species are positively associated with landscape homogeneity in the form of either open or forest habitats. We used simultaneous autoregressive models to explore the effects of climate, evapotranspiration, and landscape heterogeneity on the richness and abundance of breeding land-bird species. The richness of wide-ranging species and the total species richness were highest in heterogeneous landscapes, where many wide-ranging species showed the highest abundance. In contrast, the richness of narrow-ranging species was not highest in heterogeneous landscapes; most of those species were abundant in either open or forest landscapes. Moreover, in open landscapes, narrow-ranging species increased their species richness with decreasing temperature. These results indicate that heterogeneous landscapes are associated with rich bird diversity but that most narrow-ranging species prefer homogeneous landscapes - particularly open habitats in colder regions, where grasslands have historically predominated. There is a need to reassess the generality of the heterogeneity-biodiversity relationship, with attention to the characteristics of species assemblages determined by environments at large spatiotemporal scales. © 2014 Katayama et al.
Mikami O.K.,Iwate Medical University |
Mikami K.,Japan Bird Research Association
Landscape and Ecological Engineering | Year: 2014
The number of avian species in urban areas throughout the world, particularly in Europe and the USA is low; however, their total density is higher than that observed in surrounding habitats. Nevertheless, it has not been confirmed whether this is true in Japan. Japanese cities have fewer green areas than European and American cities, and Japanese suburbs are likely to face forests on mountain slopes, whereas cities in most other countries face open grasslands, rural areas, or flatlands. These differences could influence the structure of avian diversity from city to native habitat. We compared the number of species and individuals of all species among city centers, suburbs, and forested areas in Japan. Similar to other countries, the structure of avian communities in Japanese cities was dominated by a handful of species, and total abundance was highest among the other environments. This suggests that the underlying mechanism determining the structure of the avian community is the same between Japan and other previously studied countries. However, species richness was not the highest in the intermediate areas, which is typical in Europe and the USA. This is because suburbs face forested areas and moderately urbanized areas are scarce in the study area. The lack of intermediate area is moderately typical in Japan. This difference is important not only for managing avian diversity but also total diversity from the city to native habitats in Japan. © 2012 The Author(s).
Bonisoli-Alquati A.,University of South Carolina |
Koyama K.,Japan Bird Research Association |
Tedeschi D.J.,University of South Carolina |
Kitamura W.,Tokyo City University |
And 5 more authors.
Scientific Reports | Year: 2015
A number of studies have assessed or modeled the distribution of the radionuclides released by the accident at the Fukushima-Daiichi Nuclear Power Plant (FDNPP). Few studies however have investigated its consequences for the local biota. We tested whether exposure of barn swallow (Hirundo rustica) nestlings to low dose ionizing radiation increased genetic damage to their peripheral erythrocytes. We estimated external radiation exposure by using thermoluminescent dosimeters, and by measuring radioactivity of the nest material. We then assessed DNA damage by means of the neutral comet assay. In addition, we conducted standard point-count censuses of barn swallows across environmental radiation levels, and estimated their abundance and local age ratio. Radioactivity of nest samples was in the range 479-143,349 Bq kg-1, while external exposure varied between 0.15 and 4.9 mGy. Exposure to radioactive contamination did not correlate with higher genetic damage in nestlings. However, at higher levels of radioactive contamination the number of barn swallows declined and the fraction of juveniles decreased, indicating lower survival and lower reproduction and/or fledging rate. Thus, genetic damage to nestlings does not explain the decline of barn swallows in contaminated areas, and a proximate mechanism for the demographic effects documented here remains to be clarified.
Kazuo K.,Japan Bird Research Association |
Satoe K.,Japan Bird Research Association |
Seiichi A.,43 1 Odaira cho Mutsu shi
Ornithological Science | Year: 2013
We studied the effects of climatic conditions on the number of juvenile Whooper Swans wintering in Aomori Prefecture, northern Japan, from 1983 to 2009. We analyzed the relationship between the abundance of wintering juveniles and eight climatic variables using generalized linear models; (May and June temperatures recorded in Cokurdah, Yakutia, Russia within their breeding range, the temperature in Nikolayevsk-na-Amure within their migratory stopover range, snowfall in Obihiro, Hokkaido, a stopover site, and temperature and snowfall of the previous and present years in Nobechi, Aomori Prefecture, where they winter. The models with good fit showed that the mean highest daily temperatures in May on the breeding grounds had a positive effect on the abundance of wintering juveniles, while the total snowfall of both previous and present years in the wintering range had a negative effect on juvenile abundance. © The Ornithological Society of Japan 2013.
Saito K.,University of Tokyo |
Nakamura K.,University of Tokyo |
Ueta M.,Japan Bird Research Association |
Kurosawa R.,Japan Bird Research Association |
And 5 more authors.
Ambio | Year: 2015
We have developed a system that streams and archives live sound from remote areas across Japan via an unmanned automatic camera. The system was used to carry out pilot bird censuses in woodland; this allowed us to examine the use of live sound transmission and the role of social media as a mediator in remote scientific monitoring. The system has been streaming sounds 8 h per day for more than five years. We demonstrated that: (1) the transmission of live sound from a remote woodland could be used effectively to monitor birds in a remote location; (2) the simultaneous involvement of several participants via Internet Relay Chat to listen to live sound transmissions could enhance the accuracy of census data collection; and (3) interactions through Twitter allowed members of the public to engage or help with the remote monitoring of birds and experience inaccessible nature through the use of novel technologies. © 2015, The Author(s).
Amano T.,Japan National Institute for Agro - Environmental Sciences |
Amano T.,University of Cambridge |
Szekely T.,University of Bath |
Koyama K.,Japan Bird Research Association |
And 3 more authors.
Biological Conservation | Year: 2010
The loss of biodiversity is an ongoing problem and it is essential that a framework is established for revealing the status, identifying threats and monitoring future changes of populations. This study focuses on wader populations in the East Asian-Australasian flyway, and aims to develop a three-step framework for monitoring the status of populations. First, population changes of waders are quantified by estimating population indices from nationwide survey data in Japan between 1975 and 2008. Second, species characteristics shared by declining waders are identified using a phylogenetic comparative method. Finally, based on the revealed characteristics of declining species, composite indices are created for monitoring changes in wader communities in the East Asian-Australasian flyway. The estimated population indices revealed that 12 species out of 41, and 16 out of 42 have declined significantly during spring and autumn migration, respectively, in at least one of the past 10, 20 or 30 year-periods. Phylogenetic comparative analysis revealed that both the use of rice fields and dependence on the Yellow Sea negatively affected the population trends of waders. These results are consistent with the hypothesized negative impact of agricultural intensification caused by land consolidation in Japanese rice fields, and habitat loss and/or degradation in the Yellow Sea caused by the rapid growth of populations and economies in China and South Korea. The framework developed in this study can be applied to a wide range of species, and should play an important role in monitoring population trends and identifying threats to those species in future. © 2010 Elsevier Ltd.
PubMed | Toyo University, Tokyo University of Technology, Japan Bird Research Association and University of Tokyo
Type: | Journal: Ambio | Year: 2015
We have developed a system that streams and archives live sound from remote areas across Japan via an unmanned automatic camera. The system was used to carry out pilot bird censuses in woodland; this allowed us to examine the use of live sound transmission and the role of social media as a mediator in remote scientific monitoring. The system has been streaming sounds 8h per day for more than fiveyears. We demonstrated that: (1) the transmission of live sound from a remote woodland could be used effectively to monitor birds in a remote location; (2) the simultaneous involvement of several participants via Internet Relay Chat to listen to live sound transmissions could enhance the accuracy of census data collection; and (3) interactions through Twitter allowed members of the public to engage or help with the remote monitoring of birds and experience inaccessible nature through the use of novel technologies.
Arakida H.,Tokushima University |
Mitsuhashi H.,Museum of Nature and Human Activities |
Kamada M.,Tokushima University |
Koyama K.,Japan Bird Research Association
Aquatic Conservation: Marine and Freshwater Ecosystems | Year: 2011
Several recent studies have predicted potential habitats along coastal areas using large-scale physical environmental variables to identify target areas for conservation. However, no indices or methodologies for predicting tidal-flat habitats at a large spatial scale have been developed. Tidal flats supporting large populations of shorebirds have been identified in semi-enclosed seas. Thus, bays are probably important topographic units for evaluating the locations of shorebirds' non-breeding habitats. A GIS-based methodology was developed to extract 'bay units' at any scale from coastline data. Using three environment variables (the area of the bay units at three spatial scales, the percentage of shallow water area in each bay unit, and the spring-tide range), it was possible to predict tidal-flat habitats for six shorebird species with high accuracy (AUC>0.95, sensitivity >90%). Results showed that the percentage of shallow water area in small- and medium-scale bays was the best predictor of tidal-flat habitats, followed by the area of bays at a large spatial scale. This indicates that the size (scale) of a bay and the percentage of shallow water present are highly related to the presence of tidal-flat habitats. The prediction maps for individual species of shorebirds clearly showed differences in the distribution patterns of species. These maps were overlaid to identify potentially species-rich areas and thus where conservation and restoration of the tidal flats in these bays would be important. The model, which uses simple coastal data, is a useful, resource-efficient method for identifying target conservation and restoration areas across broad scales. © 2011 John Wiley & Sons, Ltd.
Mikami K.,Japan Bird Research Association
Ornithological Science | Year: 2016
The status of the two taxa of Pericrocotus minivets recorded in northeast Asia (divaricatus and tegimae) is controversial, with some authorities considering them subspecies but most considering them full species. Therefore, in order to further understand the status of these taxa and to elucidate geographic patterns of morphometric variation in their populations, I examined 85 museum specimens col-lected from Japan and neighbouring territories. The results confirm that morphometric differences exist between the two taxa, the northern migratory divaricatus and the southern sedentary tegimae, and that these differences are statistically significant. However, the results also reveal that there is considerable geographic variation, in terms of wing length, between populations within each taxon. In particular, the population of tegimae resident in Kyushu, Japan, has significantly longer wings than populations further south in the Nansei Shoto; and populations of divaricatus from the Korean Peninsula and adjacent regions have smaller beaks and shorter wings than the population in Honshu, Japan. © The Ornithological Society of Japan 2016.