Abstract. Roost-site preferences of the tree-roosting bat (Myotis ikonnikovi) were examined using radio telemetry. Field investigations were conducted in Nikko, Tochigi, Japan, during the summers of 2001 and 2002. We radio-tracked nine bats, and 16 roost trees were found. Bats actively selected snags, more decayed stages of snags and larger stem diameters, compared to available trees in roost plots and trees in random plots. Bats changed roosts every 1 or 2 days. Low roost fidelity indicated that M. ikonnikovi needed many roosting trees. Of these roost trees, six were determined roost-sites: Four roosts were located under bark, one was in a small cavity of a broken stem, and one was in a narrow space between a climbing vine (liana) and a trunk. To improve conservation of M. ikonnikovi, a substantial number of snags and large trees must be preserved in the bat's habitat.

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