Roost selection by the long-tailed bat, Chalinolobus tuberculatus, in temperate New Zealand rainforest and its implications for the conservation of bats in managed forests

Abstract

Roost selection by the threatened New Zealand long-tailed bat (Chalinolobus tuberculatus) was examined in temperate beech (Nothofagus) rainforest in New Zealand. Seventy-three bats were radio-tracked during the summers of 1993–1997 to 304 roost cavities in 291 different trees. Roost tree and site characteristics were compared with those of 593 randomly selected trees. Bats selected roosts on the basis of topography, forest composition and tree characteristics. Ninety-five percent of roost trees were in mature, open-structured lowland forest on the relatively flat valley floor within 500 m of the forest edge. Four tree species (including dead trees) were used as day roosts. C. tuberculatus did not discriminate between tree species per se, but selected roost trees on the basis of functional characteristics associated with these trees. Bats actively selected taller trees which had relatively low canopy closure, larger stem diameters, larger trunk surface areas and greater numbers of cavities than random trees. Red beech (Nothofagus fusca) and dead trees were most likely to provide these preferred characteristics. Seventy-four percent of roost trees were c. 100–>600 years of age. Such trees are targeted for removal under most forest management practices. Selection of specialised roosts, high roost lability and low levels of roost re-use indicate that C. tuberculatus need large areas of mature forest. We predict that outside protected areas, the low availability of suitable roost trees may limit bat populations. ©