Butterflies are very sensitive to changes in their environment and are good “environmental indicator organisms” for looking at the relationship between the environment and fauna. Therefore, by comparing the habitat status of specific butterflies with the past, it is possible to estimate changes in regional biodiversity, which can be used for future nature conservation. Butterflies are sensitive to rapid environmental change. Even a relatively simple survey of butterfly habitat can reveal changes in the environment around us. It is an effective way for local residents to gain direct insight into the effects of recent climate change and urbanization.

The description of the survey by the Ministry of the Environment and the Monitoring Sites 1000 Satoyama Survey states that butterflies have a close relationship with certain plants throughout their life history, and thus are an indicator to assess the status of vegetation in the area. It is also pointed out that butterflies are excellent research targets because “they have an appropriate number of species, have sufficient taxonomic and ecological information, and are diurnal” (Table 1). It has been reported that changes in land use and the surrounding environment have led to changes in the number and species of butterflies recorded. In Japan, the use of firewood forests and grassland management were once practiced, and many butterflies used to live in grasslands, but changes in butterflies are attracting attention as indicator species for rural areas, which are rapidly decreasing due to changes in lifestyle.

In 2004 Science Magazine, it was reported that “a comparison of historical decline trends for butterflies, birds, and plants, using the same methods and conditions, showed that butterflies had declined the most.” Butterflies are clearly the most sensitive to environmental changes, even when compared to other organisms (Thomas et al., 2004). Butterflies are suitable survey targets as environmental indicator organisms to monitor changes in the local natural environment, and are used as a variety of environmental indicator organisms at both the national and regional levels.

The UK is the most advanced in the use of butterflies as environmental indicator organisms. A nationwide effort began in 1976, and now, more than 40 years later, there are over 4,000 observation sites, and regular observations are conducted every year. A system has been realized whereby the results are also reflected in national environmental conservation policies.

In Japan, there are nationwide efforts by the Japan Butterfly Conservation Society and the Ministry of the Environment. At the regional level, the North Fuji Foothills region is representative of such efforts. The advantages of using butterflies as environmental indicator organisms are that they are sensitive to environmental changes, they are familiar organisms that are easy to count, and it is possible to learn about local environmental changes without conducting a large-scale survey. Surveys can quickly detect changes that are difficult to notice at first glance, such as forest degradation and loss of biodiversity due to environmental changes (Table 1). These are likely to be effective tools in developing countries where climate change and forest degradation are rapidly progressing, but where technology and funds to accurately measure their impacts are lacking.

The Ministry of the Environment has set up approximately 1,000 monitoring sites throughout Japan regarding the terrestrial, freshwater and marine ecosystems of the Japanese archipelago, and is continuously conducting basic environmental information surveys (Monitoring Site 1000). Among these, butterflies are surveyed at sites in alpine zones and rural areas, and citizen researchers are responsible for monitoring the rural areas. The “Monitoring Sites 1000 Satoyama Survey” has 18 “core sites” and approximately 220 “general sites” throughout Japan, and observations are being continued. The former core sites are evenly distributed across a variety of climatic zones, while the latter general sites are places where cooperation areas have been registered by volunteers (Figure 1).

A commonly used method for surveying butterfly communities is the line transect method. The line transect method involves setting up a survey route and walking along the route to record butterflies seen within a certain width on either side.

A simple monitoring method is the “field monitoring schemes for butterflies in the garden” conducted by the NPO of Japan Butterfly Conservation Society. Volunteers from all over Japan observe butterflies for about 30 minutes at least once a month at a designated spot such as a garden, balcony, or neighborhood park, record the species and number of butterflies, and report the results to the society. The results are published online by the society (Butterflies in the Garden: Enjoy the Butterflies Around You). The unique feature of this survey method is that it conducts observations in everyday living spaces such as gardens and balconies, and the survey sheet has an extremely simple format, so the barrier to participation is low and many citizen volunteers can participate.

Which method is suitable for developing countries depends on the situation and size of the local forest, the number of participants in the study, and the availability of budget. What is important is to continue the research over the long term, and it is important to establish a system for conducting the study in a sustainable manner.

As mentioned above, the Ministry of the Environment’s “Monitoring Sites 1000 Satoyama Survey” and the Butterfly Conservation Society’s “field monitoring schemes for butterflies in the garden” are two examples of efforts that use butterflies as environmental indicator organisms.

The “Monitoring Sites 1000 Satoyama Survey” is a project that continues to study the growth and habitat of plants and animals in the same way for 100 years. The purpose of this survey is to locate survey points all over the country to capture changes in the natural environment throughout Japan, and butterflies are included in one of the survey items. Currently, about 200 locations are being observed mainly by citizen surveyors.

The “field monitoring schemes for butterflies in the garden” is similarly designed to monitor changes in the natural environment by observing butterflies in various regions of Japan. The “field monitoring schemes for butterflies in the garden” provides a platform for butterfly lovers across the country to conduct regular observations of butterflies in their “gardens” and share the results online (google map).

The first site for the “Monitoring Sites 1000 Satoyama Survey” was established in 2008, while the “field monitoring schemes for butterflies in the garden” began in 2013. Both have a short history, and it is hoped that meaningful information will be derived through continued observation. Furthermore, both surveys are carried out by local citizen volunteers, and by making the system open to everyone, it is hoped that this will improve the environmental awareness of participants.

As a regionally specific example, the Mount Fuji Research Institute, Yamanashi Prefecture Government has a history of understanding changes in the natural environment around the forests at the northern foot of Mt. Fuji through observations of butterfly habitat and ecology. Similar efforts are being carried out by the NPO Mt. Fuji Nature Conservation Center, and the survey results are being reflected in local conservation activities such as Satoyama (rural landscape) burning and the installation of deer fences (Figure 2). What has been confirmed through these observations is that the number of butterflies has decreased dramatically over the past 30 years, and that in recent years new southern butterflies have been discovered almost every year. On the other hand, valuable data has been obtained, including that the numbers of northern and alpine butterflies are decreasing every year, and that the altitude of the spawning sites of certain butterflies is increasing every year. The results clearly reflect the effects of global warming due to climate change and a decrease in edible plants due to deer damage.

In many developing countries, including Cambodia, forest monitoring is rarely conducted on a national scale, and there are few opportunities to understand forest environmental changes (Figure 3). Environmental assessment using butterflies requires little technology or equipment and can be conducted with the participation of local residents. The effects of recent climate change and forest development have a significant impact on the environment and health of forests. Using butterfly monitoring methods to conduct regional-level observations can help prevent serious impacts and take early countermeasures. This will also lead to climate change mitigation and adaptation measures.

In Japan, there is no system to ensure that environmental monitoring efforts at the national level are reflected in policy. However, at the regional level, there are examples where long-term observation results have contributed to regional policies and conservation activities (Figure 4). For example, there are many butterfly enthusiasts in Japan, who have continued to observe butterflies on an individual level for many years, and some of them have become academically valuable records. Based on this, we can see the changes in the environment. There are many examples of volunteer activities leading to local environmental conservation activities. Even in its simplest form, long-term observation provides valuable data. When applied to developing countries, it is important to set up the survey methodology from the viewpoint of whether residents are comfortable with the approach.

The Japan Butterfly Conservation Society and the Nature Conservation Society of Japan are known for butterflies in Japan. English websites include Butterfly Conservation (UK) and North American Butterfly Association (NABA) (USA). Wikipedia’s Butterflies by country has information on butterfly species and ecology by country.

• Butterflies in the garden https://butterfly-garden.jp/
• Monitoring Sites 1000 Satoyama Survey https://www.nacsj.or.jp/activities/guardians/moni1000/
• United Kingdom Butterfly Monitoring Scheme https://www.ukbms.org/

• Thomas, J. A., Telfer, M. G., Preston, C. D., Greenwood, J. J. D., Asher, J., Fox, R., Clarke, R. T. and Lawton, J. H., 2004. Comparative Losses of British Butterflies, Birds, and Plants and the Global Extinction Crisis. Science, 303 (5665): 1879-1881.