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.
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 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).
Okahisa Y.,Rikkyo University |
Morimoto G.,Rikkyo University |
Morimoto G.,Toho University |
Takagi K.,Japan Bird Research Association |
Ueda K.,Rikkyo University
Bird Study | Year: 2013
Capsule Moult of greater coverts in the wintering area is correlated with a decrease in spring arrival condition but not arrival time of yearling male Narcissus Flycatchers. © 2013 British Trust for Ornithology.
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.