The Living World/People and Society

Tohru Ikeda

Thinking about Environmental Conservation from the Perspective of the Relationship between Humans and Wildlife

Tohru Ikeda , Professor

Graduate School of Letters (Department of Humanities and Human Sciences, Faculty of Letters)

High school : Hokkaido Sapporo Minami High School

Academic background : Graduate School of Letters, Hokkaido University

Research areas
Conservation ecology, wildlife management, regional science
Research keywords
Ecology, biodiversity, alien species, environmental conservation, fieldwork

Why are you engaged in ecological research in the Faculty of Letters?

Figure 1. Research fields related to the issue of alien species

Environmental issues are among the many serious issues that we face. Everyone knows how important it is to protect the environment around us, but because it takes so long for us to recognize changes in the environment and how they affect us, understanding the causal relationships involved can be extremely difficult. They say that Homo sapiens is the lord of all creation. However, we are just another species inhabiting this planet, and even in the present age with all the advances we have made in science and technology, our lives are still bound by our relationship to other organisms. It is high time we recognized how we impact on the environment and think about how to strike a balance between development and environmental conservation.
The focus of my current research is on the ecology of alien raccoons and other alien species, and on measures for dealing with the problems they cause. Alien species are species that, as a result of human activities, have been introduced into a habitat in which they were not originally present. Those alien species deemed to pose a threat to the biodiversity of the habitat in which they establish themselves are also called invasive alien species. Since the study of alien species and the problems they cause is concerned with animals, no one could be blamed for thinking of it as an area of natural scientific research, but it is people who are the root cause of alien species issues, which accordingly need to be tackled from various perspectives. Taking the raccoon problem as an example, studying raccoon ecology is of course essential to any control measures, but in addition to damage to ecosystems, we also need to investigate crop damage as a result of predation by pests in general, and issues related to the management of pets and other domestic animals from which alien species are derived. We also need to think about bioethical aspects regarding disposal of captured animals and consider risk management along with local culture, religion, and history in order to implement effective measures. In other words, alien species are indeed a broad social issue requiring multifaceted analysis and treatment spanning both the sciences and humanities, including consideration of evolutionary and other aspects of the long-term relationship between mankind and other organisms (Figure 1).


What kinds of devices and methods do you use in your research?

My chief research method is fieldwork. When studying animal ecology, in addition to field observations, we use devices such as motion detection-equipped infrared cameras (Photo 1) to check on conditions, such as animal presence and damage, and radio telemetry (transmitters attached to animals) to track movements within home ranges. When implementing control measures, we not only draw up control plans, but also use box traps and other capture devices to collect field data aimed at developing effective and efficient control techniques. My fieldwork involves more than just studying animals. I also interview farmers, who have suffered damage caused by invasive alien species, and people involved in control measures so as to identify issues and demands, and improve control measures accordingly. As an example of technology that combines such aspects, we leveraged the habit of raccoons to den in hollow trees to develop nest-box traps that do not require bait and are designed to automatically send text messages when an animal has been trapped. This eliminates the need to go around and inspect traps every day, thus addressing demand for low-cost raccoon control technology that does not consume a lot of time. We enlisted the help of a zoo, and I conducted repeated experiments with my students to test various prototypes (Photo 2) until we finally succeeded in capturing raccoons in the field. 

Photo 1. Raccoon filmed by a motion detection infrared camera

Photo 2. Experiment using zoo raccoons to develop a box trap

  Although invasive alien species control measures tend to be focused on agricultural damage, we are also developing control measures aimed at local environmental conservation that involve public/private sector cooperation between local government, environmental NPOs, local residents and university researchers like me, and we cooperate with local residents in the study area to conduct our research. We are also building a nationwide network of people involved in raccoon control, and seek to ensure that our research results are put to use for the benefit of society.


What do you plan to do next?

I started studying alien species at a time when they had not become a big issue in Japan, and having seen the way my research has been applied to actual control measures and policies, I feel that I have been able to contribute to society through raising public awareness of the issue of alien species. I want to continue focusing on research aimed at developing effective control measures in Japan, but I’m also hoping to broaden research perspectives by building closer ties with overseas researchers, particularly those in New Zealand, which is currently the world leader in alien species research and control measures.
Also, insofar as the prime objective of alien species control is the conservation of local environments and biodiversity, our research would be incomplete unless it goes beyond the elimination of invasive alien species to address the recovery of native species that have been adversely impacted by invasive alien species. As such, I am also eager to conduct research that contributes to the restoration of ecosystems and native species disturbed by the introduction of alien species.



(1) Tohru Ikeda (ed.), Living Organisms as Culture: The Diverse Interrelationships between Humans and Other Life Forms (Seibutsu to iu bunka: hito to seibutsu no tayou na kakawari) Hokkaido University Press (2013)
(2) Fumio Yamada, Tohru Ikeda, Go Ogura Alien Mammals of Japan: Management Strategies and Ecosystem Conservation (Nihon no gairai honyurui: kanri senryaku to seitaikei hozen) University of Tokyo Press (2011)