Habitat use and nocturnal activity of lesser short‐tailed bats (Mystacina tuberculata) in comparison with long‐tailed bats (Chalinolobus tuberculatus) in temperate rainforest

Abstract

Habitat use and nocturnal activity patterns of the threatened lesser short‐tailed bat (Mystacina tuberculata) were sampled during late spring and early summer using automatic bat detector units in temperate beech (Nothofagus) rainforest in Fiord‐land, New Zealand. Detector units recorded the number of bats passing per hour as an index of activity. Habitat use patterns were compared with long‐tailed bats (Chalinolobus tuberculatus) sampled concurrently. Activity levels in lesser short‐tailed bats varied significantly among five habitat types and amongst hours of the night. Of the total activity recorded, most passes (82.6% of n = 657 bat passes) were in red beech forest >200 m from the forest edge; 13.7% were in silver beech within 100 m of forest edges, 2.6% were along roads through forest, 0.9% were on the forest‐grassland edge, and 0.2% were in the open grassland. Lesser short‐tailed bats were active throughout the night but especially at dawn and dusk. There was no correlation between levels of activity by lesser short‐tailed bats and overnight minimum or dusk temperatures. Patterns of habitat use and activity in long‐tailed bats were significantly different from those of lesser short‐tailed bats. Of the total activity recorded, most (56.0% of n = 2929 bat passes) was along forest‐grassland edges; 15.7% of passes were in open grassland, 13.1% were along roads through forest, 11.0% were in silver beech forest within 100 m of forest edges, and 4.2% within red beech forest. The implications of these findings for conservation and for improving survey techniques are discussed. For example, lack of use of open and edge habitats by lesser short‐tailed bats suggests they would not adapt to highly fragmented and cleared forest habitats. The two species of New Zealand bat used available habitats differently while inhabiting the same sites. Therefore, a range of habitats, including forest interior, forest edges and grasslands, are required to sustain both species within reserves and management areas. Surveys for lesser short‐tailed bats should focus on mature forest stands >200 m into the forest to maximise the chance of encountering this species, whereas surveys for long‐tailed bats would best focus on forest edges.