Characterization of the Temperature Conditions of Inside Narrow Rocky Outcrops that Serve as a Habitat for Semi-Fossorial Mammals

Masahiro A Iwasa,Mayuh Tabata

doi:10.4236/ojas.2016.64030

Abstract

We characterized the temperature conditions inside narrow rocky outcrops that served as habitats for semi-fossorial small mammals in a mountainous locality on the Japanese Islands. Usually, it is considered that the narrow rocky outcrops have poorer resources than the soil ground of forest floors, which have rich vegetation and nutrition. On the basis of this tendency, it is considered that ecologically dominant species occupy the rich soil habitats and subordinate species are chased away to the narrow rocky outcrops by ecological species competitions, resulting in habitat segregation. However, the present temperature data revealed that the temperatures inside rocky terrains were more stable than the shaded ambient temperatures in the forest. The rocky habitats were apparently colder in summer and warmer in winter, in both daily maximum and minimum temperatures, than the ambient temperatures in the forest during the research period. In addition, the daily difference between maximum and minimum temperatures in the rocky habitats was apparently smaller than that of the ambient ones. These temperature conditions in the narrow rocky outcrops are advantageous to the small mammalian metabolic system. Namely, we estimate that the semi-fossorial small mammals are not chased out by the dominant species through ecological competitions and that the semi-fossorial small mammals may occupy the narrow rocky outcrops as a more advantageous habitat than the forest floor.

Highlights

Of the several environmental elements for the habitat preferences of the terrestrial and semi-fossorial mammals, we focused on the temperature of the habitat and evaluated the temperature conditions in narrow rocky outcrops as an ecological habitat advantage for these species
A. speciosus, A. argenteus, and U. talpoides were collected from forest floors in site A
In the present trapping results, a few species of terrestrial and semi-fossorial small mammals were collected at the rocky outcrops irrespective of capturing only three species of terrestrial small mammals at forest floors in site A (Figure 2)

Summary

Introduction

In natural conditions of Honshu of the Japanese Islands, the red-toothed shrews, Sorex. Tabata shinto and S. hosonoi, the Japanese shrew-moles, Dymecodon pilirostris and Urotrichus talpoides, the red-backed voles, Eothenomys andersoni and E. smithii, and the Japanese field mice, Apodemus argenteus and A. speciosus, are recognized in rock outcrops as small mammalian species [1]-[4]. The Sorex shrews, D. pilirostris, U. talpoides, E. andersoni and E. smithii use incomplete burrows and rock crevices as well as ground, and are considered to be typically semi-fossorial species [1]-[4]. The Apodemus species widely occur on forest floors, grass fields, and cultivated fields as terrestrial species, and A. argenteus shows spatial usage of trees as a semi-arboreal species [4]-[7]

Methods

Results

Conclusion