Contrasting habitat use of morphologically similar bat species with differing conservation status in south-eastern Australia
The east-coast free-tailed bat Mormopterus norfolkensis Gray, 1839 is a threatened insectivorous bat that is poorly known and as such conservation management strategies are only broadly prescribed. Insectivorous bats that use human-modified landscapes are often adapted to foraging in open microhabitats. However, few studies have explored whether open-adapted bats select landscapes with more of these microhabitat features. We compared three morphologically similar and sympatric, molossid bats (genus Mormopterus) with different conservation status in terms of their association with vegetation, climate, landform and land-use attributes at landscape and local habitat element scales. We predicted that these species would use similar landscape types, with semi-cleared and low density urban landscapes used more than forested and heavily cleared landscapes. Additionally, we explored which environmental variables best explained the occurrence of each species by constructing post-hoc models and habitat suitability maps. Contrary to predictions, we found that the three species varied in their habitat use with no one landscape type used more extensively than other types. Overall, M. norfolkensis was more likely to occur in low-lying, non-urban, riparian habitats with little vegetation cover. Mormopterus species 2 occupied similar habitats, but was more tolerant of urban landscapes. In contrast, Mormopterus species 4 occurred more often in cleared than forested landscapes, particularly dry landscapes with little vegetation cover. The extensive use of coastal floodplains by the threatened M. norfolkensis is significant because these habitats are under increasing pressure from human land-uses and the predicted increase in urbanization is likely to further reduce the amount of suitable habitat.
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