Bird Research Vol. 13(2017)

We have engaged in acoustic monitoring inside and outside of the evacuation zone suffered the impact of the Fukushima Daiichi nuclear power plant accident since 2014. Not only to promote communication between researchers and local community but also to improve transparency of the research processes, we held an event, “Bird Data Challenge in Fukushima”, in 2015. In the event, we listened to the audio data and made the identified species list of birds with participants using a newly-developed web-based interface for acoustic identification, “SONO-TORI”, and a semi-real-time visualization system, “SONO-TORI VIS”. In the event, 30 participants were divided into five small groups, and listened to the audio data of 63 minutes and succeeded to identify 23 bird species in total. The results of questionnaires on the participants showed that the level of satisfaction and willingness to revisit was substantially high. We also found that mutual communication between participants and improvement of identification skill had significant effects on the level of satisfaction. Although there are several things to be improved in the way to share the result with participants and to assign the appropriate tasks, our attempt showed a potential of identification of birds from recorded birdsongs as an event format of citizen-participating survey.

We observed the flight behavior of white-tailed sea eagles Haliaeetus albicilla at the town of Tomamae in northern Hokkaido from 2009 to 2016, to determine how the eagles’ flight behavior was affected by updrafts created by the topography of coastal cliffs. The frequency, location, direction and speed of eagle flights were recorded by theodolite, along with weather conditions and topographic variables. Based on those variables, a statistical model of flight behavior was created. The eagles flew in the study area most frequently when the wind blew in the west-northwesterly direction (29.5%), and in the westerly direction (23.5%). The statistical model, based on the flight frequency of the eagles and the terrain variables in the 10m grid, indicated that slope degree, slope direction (east-northeast and west-northwest), number of cliffs, and presence of coastline had a positive effect on the flight frequency. Based on this model, we performed a numerical simulation of airflow in the survey area. As a result, it was determined that as the wind velocity increased, the resulting updraft generated by the coastal cliff developed farther away from the cliff. The eagles were observed flying farther out to sea when the wind blew stronger, apparently to make use of the updraft located further from the shore. The observed flight speed of eagles flying along the cliffs was less than the minimum flight speed required to maintain their altitude, as estimated by the general lift model. In this case, eagles would be expected to lose altitude and descend. However, the result of the simulation showed that the updraft at the particular position of the eagles’ flights were stronger than the estimated subsidence force. We conclude that updrafts occurring in the vicinity of the cliffs overcome the subsidence.