Increasing Deer Population Causes Serious Damage due to Overgrazing throughout Japan
Japanese sika deer, distributed over a wide area from Hokkaido to Kyushu, are familiar animals for Japanese people. Recently, the population of sika deer has been rapidly increasing in Japan. There are various reasons for the increase, including an increase in the abandoned cultivated land, a decrease in and the aging of hunting rifle holders, and sika deer living longer due to mild winters. According to a survey by the Ministry of the Environment, the sika deer habitat shows an increasing trend in most of the prefectures in Japan. The results of “Increase in Geographical Distribution of Sika Deer” show that the sika deer distribution has expanded by about 2.5 times during the 36 years from 1978 to 2014. (*1)
With an increase in the deer population, damage caused by overgrazing is also becoming more and more serious year by year. Deer destroy forests by eating nursery trees as well as branches, leaves, and barks of trees. Deer also eat flowers of rare alpine plants in the Minami Alps, causing a significant blow to nature conservation and tourism. As deer eat up the undergrowth in woodlands, the surface soil slides into rivers and contaminates the river water. It also weakens the ground and leads to landslides and related disasters. Therefore, overgrazing by deer causes environmental damage as well as human and economic damage.
Against this backdrop, in May 2015, the Ministry of the Environment designated sika deer as a “specified managed animal” before the enforcement of the amended Protection and Control of Wild Birds and Mammals and Hunting Management Law because the number of sika deer has increased rapidly and caused a significant impact on agricultural crops and ecosystems. As a result, in addition to the national government, Japan’s local prefectures have been a driving force behind moving forward on implementing countermeasures against overgrazing.
So far, the Ministry of the Environment and local prefectures have directly sent researchers into target areas and conducted habitat surveys to effectively implement measures against sika deer. However, with the expansion of habitable areas of sika deer, it has become necessary to expand the survey area, and accordingly, the time needed and the number of researchers must also increase. Moreover, there were existing issues with how to conduct a survey of the areas that were difficult for researchers to enter and investigate.
(*1) Source: Website of the Ministry of the Environment
Developed a Software Technology for Predicting the Maximum Possible Animal Populations without Having to Conduct Field Surveys
Fujitsu Laboratories Ltd. announced the development of software technology to predict the maximum population of mammals that can inhabit an area from information such as the average weight of an animal and public data on vegetation and land use, and predicted the maximum population of sika deer in a 10-square kilometer area in Kofu in Yamanashi Prefecture (Figure 2). Using vegetation and land-use maps and topographic maps, as well as assumptions about sika deer biology, the area was divided into i) habitable areas that are suitable for deer to live, ii) uninhabitable areas that are unsuited for deer, and iii) corridors that are not suited for habitation but that could be used to move through the district. The habitable areas connected by corridors were then extracted, and, by applying the relational expression between sika deer population density and their weight, the maximum possible population number for each square kilometer area was calculated.
Improving Accuracy through the Technology Trial in Yamanashi
With this technology, Fujitsu will conduct trials in more than eight areas, each of which is 100 square kilometers, in Yamanashi Prefecture from January to September 2016 with the cooperation of the Yamanashi Forest Research Institute, which is researching the status of the forests and the biology and population of sika deer.
To improve the accuracy of this technology, Fujitsu will compare the population estimates obtained from the Yamanashi Forest Research Institute’s field survey data on the sika deer population based on the frequency of sightings by field researchers and analysis of droppings with the numbers predicted by this technology and analyze the results.
Efforts for Contributing to Preserving Biodiversity
This series of trials makes it possible to predict sika deer populations in areas where survey data have not been collected and regions that are difficult for researchers to actually go to and investigate. The estimates of habitats and corridors based on the prediction results for a broader region will also make it possible to implement effective countermeasures, such as putting up fences to restrict their behavioral range. This will help resolve existing issues.
Fujitsu will also broaden the scope of the technology’s applications to mammals other than sika deer. Through these efforts, Fujitsu will contribute to preserving biodiversity using its information and communication technology.
Fujitsu established its Biodiversity Action Principles (*2) in 2009, and in addition to its business efforts, it will proactively work to use its information and communication technology to conserve biodiversity and achieve sustainability.