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Predicting the future expansion of the distribution of Blakiston’s fish owl


Article title

Projecting range expansions of Blakiston’s fish owl under conservation activities using dynamic distribution model

Author (affiliation)

Chiaki Yoshii (a&b) ,Yuichi Yamaura (c), Yoshiko Kobayashi (a&d), Takeshi Takenaka (e), Takumi Akasaka (a&f), Futoshi Nakamura (a)

 (a) Hokkaido University
 (b) CTI Engineering Co., Ltd.
 (c) Department of Forest Vegetation, FFPRI
 (d) National Institute for Environmental Studies
 (e) FILIN
 (f) Obihiro University of Agriculture and Veterinary Medicine

Publication Journal

Japanese Journal of Conservation Ecology, 22(1): 105-120, May 2017

Content introduction

Blakiston’s fish owl (Ketupa blakistoni) is a large, piscivorous owl; its distribution is restricted to Hokkaido, Japan and eastern parts of China and Russia. This species used to be distributed throughout Hokkaido; however, its population has dwindled considerably due to widespread logging of riparian forests and changes in river hydrologic regimes. As a result, the species is currently designated as an endangered species in Japan. Although the population of the owl has been gradually recovering in recent years, particularly in eastern Hokkaido, further conservation efforts are required.

We estimate an expansion in the distribution of Blakiston’s fish owl based on a statistical model that predicts areas of suitable habitat. Consequently, the most favorable environment for the owl is the riparian ecosystem, where natural vegetation is abundant. Results also indicate the importance of encouraging reproduction in such areas to expand the owl’s distribution. Furthermore, Blakiston’s fish owl is predicted to expand into parts of the Yubari Mountains, thereby increasing its distribution. Due to multiple potential routes of dispersal, however, a great deal of uncertainty remains regarding predicting its future distribution. Our results underscore the need for continuous monitoring conducted in parallel with conservation activities.



Areas predicted to be suitable for the inhabitation of Blakiston

Figure1. Areas predicted to be suitable for the inhabitation of Blakiston’s fish owl under present environmental conditions based on the statistical model.


Predicted distribution of Blakiston’s fish owls in the next 50 

Figure2. Predicted distribution of Blakiston’s fish owls in the next 50 years based on the assumption that there will be no changes in land use over this period.

The figure shows areas with a high probability of distribution based on 1000 sessions of future predictions (simulations). This suggests that the owls may make inroads into the Yubari Mountains (circled in red), which they currently do not inhabit. High-altitude and urban areas are regarded to be barriers for their distribution.