Computer-Aided Development of Wildlife Conservation Plans

Hiroshi Momose

Recent development of technologies such as GIS (Geographic Information System), GPS (Global Positioning System), and remote sensing has facilitated the analysis of complicated three-dimensional data on animal distributions, their habitats, and so forth. Software to process such data have also become easily available on PCs. In this article, an analysis on rare raptor habitats based on the field studies conducted in Tochigi Prefecture is introduced. By describing how data are collected in the field and how they are processed by computers, it attempts to examine technological possibilities that allow GIS-supported analysis of the environment that could be linked to wildlife conservation plans.

At the Landscape and Ecology Division in the Environment Department of the National Institute for Land and Infrastructure Management, in the Ministry of National Land and Transport (formerly called the Public Works Research Institute of the Ministry of Construction), we are now working on a project called the "Study of Integration and Utilization of Ecological Information." The purpose of the project is to develop the system such as captures of the general nature outlook of the area using remote sensing and other technologies and prepares the information we got as a GIS database, from which the necessary information at every step of the assessment could be provided.

Selected as the model site for the study was an area of 11.0 km (in a north-south direction) by 24.6 km (in a east-west direction) located across Utsunomiya to Haga, in Tochigi. Environmental information of that area such as vegetation, geography, land use, and climate was collected to build a GIS database. [See fig. 01.]

In the same area, habitat condition of raptors such as Goshawks and Grey-faced Buzzards was also investigated, so that the results could be linked to the vegetation, geography, and other environments. In response to recent calls for measures to conserve rare raptors in implementing various development projects, the study intends to acquire fundamental knowledge concerning the conservation of raptors. In the following paragraphs, the Grey-faced Buzzard, a middle-size migratory raptor species, is taken as an example to discuss and analyze rare raptor¡Çs preference for habitat and environments by using GIS.

The Grey-faced Buzzard is a species of hawk for which a decline in population has been pointed out in recent years, and conservation measures are expected to be needed in the future. The survey on Grey-faced Buzzards was conducted three to five times during their breeding season from mid-April through July 1999, by searching the forest edge throughout the survey area to determine how their nesting places are distributed.

The results revealed that there were 116 nesting places of Grey-faced Buzzards in the area, out of which actual nests were spotted at 33 sites [fig. 02]. The entire survey area was divided into square blocks of approximately 2 x 2 kilometers and a multiple linear regression analysis was used for each of them, where the population of Grey-faced Buzzards within the block was used as the objective variable. The predictor variables were: the area of woods, the length of the boundary between woods and paddy fields, the ratio of paddy field area to its perimeter, the area of woods in the surrounding blocks, and human population.

The analyses stated above yielded a determinant coefficient figured out as r2 = 0.812 between the population of Grey-faced Buzzards and the variables representing the environment, indicating significant relationship thereof [fig. 03]. The variables that showed highest contribution ratios were the length of the boundary between woods and paddy fields and the area of woods in the surrounding blocks. It suggests Grey-faced Buzzards favor a habitat where there is a longer string of area with abundant.

The results show that more than 80% of the variation in population (density) of Grey-faced Buzzards can be explained by environmental factors such as vegetation, although there is room for improvement in this model. Such a model completed for every species of rare raptors as well as for other species that need to be conserved would allow, for instance, estimation of latent populations of rare raptors for a certain area and evaluation of the quantitative effects of a planned project (comparison of the impact of two development plans, each based on a different scenario, and so on). [See fig. 04.]

When applying these models, there are indeed a number of aspects that should be taken into account, such as regional differences and the accuracy of environmental data. While improving applicability of the Grey-faced Buzzard habitat prediction model by adding survey results from other areas, we will continue our studies to develop similar habitat models for other rare raptor species too.

References

1. Hiroshi Momose, Nobuo Fujiwara, Naomi Kibe, Yuko Takeda, Hitomi Oguri, and Katsuhide Yoshikawa, "Development of the Environmental Impact Assessment Support System Using an Information Infrastructure," Civil Engineering Journal 43 (8), 2001, pp. 32-37.

2. Hiroshi Momose, Ueda, Nobuo Fujiwara, and Takehiko Ishizaka, "Occurrence and Habitat Preference of Butastur Indicus around Utsunomiya, Tochigi" The Speech Abstract for the 2000 Annual Meeting of the Ornithological Society of Japan, 2000, pp. 16.

3. Hiroshi Momose, "GIS-supported Analysis of Animal Habitats," Japanese Journal of Ecology 51, 2001 (forthcoming).