Seasonal variations in distribution patterns and movements of bats in relation to habitat characteristics

Abstract: Different types of land use, such as forestry and agriculture, change the distribution and composition of habitats in the landscape. In order to understand the consequences of that for different organisms, and to find methods for combining conservation with production of crops, timber and other products it is important to collect information on distribution pattern, habitat selection and movements of different organisms. By using ultrasound detectors, mist-nets and radio telemetry distribution patterns, abundance and species richness of bats in relation to habitat characteristics among different forest patches in "Lower Dniester" Ramsar Site, Republic of Moldova was studied. The area consists mainly of agricultural lands and highly fragmented inundated and upland forest remnants. In each habitat patch data were collected on forest age, abundance of standing dead and living trees, size of forest patches, occurrence of villages and availability of water. Data were collected during two different periods: July-August and September-October, in order to investigate potential seasonal differences on habitat selection. The result shows that the distribution pattern of bats varies significantly during different seasons. During critical periods (late in autumn), bats are restricted to some specific key habitats and there are movements of bats between key habitats and suboptimal habitats. A multivariate analysis revealed importance of standing dead tree density. From this study, it is obvious that key habitats play an important role for bat populations and that more information on habitat selection and movements of bats during critical periods is needed to improve the conservation of bats.