The Use of Road Crossing Structures in Japan by Mammals and Factors Influencing their Usage

Abstract

To enable mitigation and overcome the problems of road-kill and barrier effects, road-crossing structures (RCSs) are being installed worldwide. Previous research has shown that the structure of RCSs and the surrounding landscape pattern affect their traverse by wild animals. This article examined the factors influencing the usage of RCSs by wild mammals on the Toyotomi Bypass (TTB) in Hokkaido and the Higashi Fujigoko Expressway (HFGE) in Yamanashi. The utilization of RCSs by wild mammals was monitored using infrared sensor cameras, and the effects of structural and environmental parameters were analyzed. The structural parameters were 1) volume of RCSs, 2) openness, 3) presence or absence of drainage, 4) presence or absence of shelves, and 5) distance between the RCSs. The environmental parameters were the proportions of 1) bush, 2) non-bush, 3) anthropogenic land use, and 4) the presence or absence of existing vegetation clusters using canonical correspondence analysis (CCA). The study found that the common factor affecting the utilization of RCSs was the presence or absence of drainage. Other influential factors were the effects of structural and environmental parameters.