Influence of vegetation and abiotic factors on habitat use by insectivorous bats in subtropical mountain forests

Abstract

Forest structure and abiotic factors influence the habitat use of many mammals. For insectivorous bats, characteristics such as plant density, canopy cover, temperature, relative humidity and other seasonal changes over the course of the year can be important as regulators of food resource accessibility, and consequently of their nutritional health. The aim of this study was to determine the influence of the structure in two different forest types and of two abiotic factors, temperature and relative humidity, on habitat use by insectivorous bats in forests that present relatively small seasonal phenological changes. Sampling was conducted with ultrasonic detectors and the resulting recordings were used to analyse bat calls for identification of species and determination of bat activity. We found significant differences among the relative activities of the study species in both vegetation types. There was a tendency towards a greater increase in activity throughout the year in forests with either greater canopy cover or higher plant density. We found a positive correlation between temperature and activity in most of the recorded species, and a negative correlation between relative humidity and this activity. Our results show that relative humidity seems to be more influential than temperature on the activity patterns of insectivorous bats. Attenuation and its consequences could be more important to habitat use than heat loss in temperate subtropical forests (both cloud forest and pine forest).