Use of roosts by the long-tailed bat, Chalinolobus tuberculatus, in temperate rainforest in New Zealand

Abstract

Patterns of roost-switching behavior and roost reuse were investigated in the threatened New Zealand long-tailed bat (Chalinolobus tuberculatus) in temperate rainforest. A total of 371 roosts was monitored for 503 roost-days after radiotracking 58 bats. Bats were solitary (37.3%) or communal (62.7%). Colonies were small, averaging 34.7 bats ± 23.4 SD. Reproductive females dominated colonies, and males roosted more often by themselves. C. tuberculatus differed from other species of bats because roost-site lability was extremely high (70% of sites occupied for only 1 night), bats did not cycle around a small number of preferred roosts, females carried their young to a new roost each day, and individuals abandoned each roost simultaneously as a group. Rates of reuse were low, with 301 new roost trees found >3 years of study. All sex and age classes switched frequently between solitary and communal roosts. Solitary roosts were occupied for longer times than colonial roosts. Reproductive females predominately (although not exclusively) used colonies during pregnancy and lactation but were more often solitary during post-lactation. Ratio of communal to solitary roosts in nonreproductive bats remained the same throughout summer, but adult males switched to communal roosts more often during post-lactation, presumably to mate. We suggest that suitable roosts were abundant allowing C. tuberculatus to move frequently in response to social and thermoregulatory requirements. If the pool of suitable trees were reduced, population viability may be affected.