Citizen science is a powerful tool for collecting large volumes of observational data on various species. These data are used to estimate distributions using environmental factors with Species Distribution Models (SDM). However, if citizens are inexperienced in recognizing organisms, they may report different species as the subject species. Here we show nation-wide bumblebee distributions using photographs taken by citizens in our project, and estimated distributions for six bumblebee species using land use, climate, and altitude data with SDM. We identified species from photographic images, and took their locations from GPS data of photographs or the text in e-mails. When we compared our data with conventional data for specimens in the Global Biodiversity Information Facility (GBIF), we found that the volume and the number of species were larger, and the bias of spatial range was lower, than those of GBIF. Our estimated distributions were more consistent with bumblebee distributions reported in previous studies than with those of GBIF. Our method was effective for collecting distribution data, and estimating distributions with SDM. The estimated SDM allows us to predict the previous and future species distributions, and to develop conservation policies taking account of future city planning and/or global climate changes.

When the nutrient content of food is limited, herbivores often increase their feeding rates. Such an increase in the feeding rate is called 'compensatory feeding'. Although it has a number of implications for herbivore population and plant-forager dynamics, the compensatory feeding is not yet functionally formulated especially in relation with ecological stoichiometry. Therefore, we constructed a simple mathematical model by incorporating the optimal feeding rate into the type II functional response to maximize a forager's growth rate under constraints of carbon or nutritionally important element like phosphorus (P). We used the planktonic herbivore Daphnia as a model herbivore. The model revealed that the optimal feeding rate increased by using excess carbon when relative P content of food was less than a certain level, which is known as the threshold elemental ratio. This level changed with the change of food abundance. It also showed that whether or not foragers should exhibit compensatory feeding depends on their stoichiometric characteristics and digestive traits, and also on the assimilability of a given food. These findings are helpful to test the feeding conditions under which compensatory feeding is advantageous for a given animal. Our model can be easily incorporated into forager population dynamics and prey-consumer interaction models because the optimal feeding rate can be analytically given.

We study coupled socioeconomical and ecological dynamics for lake water pollution. Players choose between cooperative (but costly) option and economical option, and their decision is affected by the fraction of cooperators in the community and by the importance of water pollution problem. When an opportunity for choice arrives, players take the option with the higher utility (best response dynamics). This social dynamics is coupled with the dynamics of lake water pollution. First, oscillation of large amplitude is generated if social change occurs faster than ecosystem responses. Second, the model can show "paradox of nutrient removal". If phosphorus is removed more effectively either from the inflow or from the lake water, the pollution level may increase (rather than decrease) due to the decline in people's willingness to cooperate. Third, we compare the effectiveness of alternative methods in improving water quality: to reduce the cooperation cost by subsidy, to enhance people's concern to water pollution problem, and to promote the conformity among people.

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Wild bee decline has been reported worldwide. Some bumblebee species (Bombus spp.) have declined in Europe and North America, and their ranges have shrunk due to climate and land cover changes. In countries with limited historical and current occurrence data, it is often difficult to investigate bumblebee range shifts. Here we estimated the past/present distributions of six major bumblebee species in Japan with species distribution modeling using current occurrence data and past/present climate and land cover data. The differences identified between estimated past and present distributions indicate possible range shifts. The estimated ranges of B. diversus, B. hypocrita, B. ignitus, B. honshuensis, and B. beaticola shrank over the past 26 years, but that of B. ardens expanded. The lower altitudinal limits of the estimated ranges became higher as temperature increased. When focusing on the effects of land cover change, the estimated range of B. diversus slightly shrank due to an increase in forest area. Such increase in forest area may result from the abandonment of agricultural lands and the extension of the rotation time of planted coniferous forests and secondary forests. Managing old planted coniferous forests and secondary forests will be key to bumblebee conservation for adaptation to climate change.