Abstract
The number and species of small mammals that drown after falling into road-side gutters (45 cm in width and 45 cm in depth) with flowing water (10–25 cm in water depth and 1.3–1.6 m/s in velocity) were investigated. A field survey was conducted along an approximately 1.5 km stretch of gutters in Fujinomiya, Shizuoka Prefecture in Japan from June 2001 to September 2004. Data were collected from 132 observations (days). A total of 152 drowning animals, consisting of 13 small mammal species, were collected, including the nearly threatened mole, Euroscaptor mizura. Drowning animals comprised 81 percent of the species of small mammals in the study area. The average frequency of drowning was 1.16 animals per day. Microtus montebelli drowned mostly around pasture areas, which is probably due to habitat differences around gutters. Drowning of small mammals in side gutters occurred between March and November, while no drowned animals were observed between December and February. The seasonality of occurrence could be related to the breeding season of small mammals. Our study demonstrated that side gutters without cover were lethal for small mammals, and thus, it is necessary to take preventive measures when constructing side gutters.
