Ecology of long-tailed bats Chalinolobus tuberculatus (Forster, 1844) in the Waitakere Ranges : implications for monitoring
Creators: name: Alexander, Jane
Publisher: name: Zenodo
Year: 2001
Subjects: Biodiversity
Mammalia
Chiroptera
Chordata
Animalia
bats
bat

description: (Uploaded by Plazi for the Bat Literature Project) The long-tailed bat (Chalinolobus tuberculatus) is a threatened species endemic to New Zealand.  Historical anecdotes indicate that long-tailed bat populations have declined. However, it is  unknown if all populations have declined and if declines are historical or ongoing. Thus, the  development and implementation of a national network of long-tailed bat monitoring sites is a  priority of the Department of Conservation's Bat Recovery Plan. Potentially, information gained  from a national monitoring programme would assist conservation managers to target resources  towards those areas where bat populations are declining and provide baseline information to  assist managers to gauge the impact of management techniques on bat populations. Of critical  importance is that unless it can be demonstrated that long-tailed bat populations have declined  and that, that decline is real, management will not be initiated.  The aim of this research was to investigate aspects of the ecology of long-tailed bats that would  influence the development of a monitoring programme. The distribution, roost selection, habitat  use, and activity patterns of a long-tailed bat population that persisted in the Waitakere Ranges,  Auckland, were investigated. A study of the Waitakere Ranges long-tailed bat population was  significant because (1) the Waitakere Ranges is the northern most location at which long-tailed  bats have been researched; (2) the study was the first to be conducted on a long-tailed bat  population that persisted in kauri Agathis australis dominated forest remnants; (3) the long-tailed  bat population in the Waitakere Ranges is the only known extant population in close proximity to  a major urban area; and (4) the factors that are attributed to long-tailed bat population declines  (i.e., forest clearance, predation and urbanisation; O'Donnell, 2000) are likely to be ongoing and  intensified in the Waitakere Ranges. 4  Twenty roosts were located. Most roosts (85%) were in kauri, 2 were in mature rimu (Dacrydium  cupressinum) and 1 was in a kahikatea (Dacrycarpus dacrydioides). All roosts were in large,  live, emergent trees. Mean height of roost trees was 38.4 ± 1.3 m and average DBH was 186 ±  12 cm. The entrances of six roost cavities were identified all were located in minor lateral  branches in the crown of the tree and were primarily near the tip of branches. Roosts were a  mean height of 24.6 ± 3.7 m above ground level. It was argued that roosts in the crowns of kauri  were inaccessible to terrestrial mammalian predators.  Twenty-eight roost watches were conducted. The average number of bats counted leaving roosts  was 10.0 ± 1.5 (maximum = 24). Roosts were occupied by radio-tagged bats for an average of  2.0 ± 0.4 days, and 11 (55 %) were occupied for only one day. Roost size was the lowest  reported for long-tailed bats. Roost switching also appeared higher than in other populations that  have been studied. It was argued that morepork predation may have a significant impact on the  population viability of the population.  As in other studies long-tailed bats were found to forage over modified habitats including over  farmland, dwellings, orchards and along streams and roads with little vehicular traffic. Longtailed bats foraged throughout the Waitakere Ranges and their foothills. Bat activity was highly  variable. Of the environmental variables analysed, temperature was found to have the greatest  influence on bat activity. There were seasonal and habitat influences on bat activity. The  relationship between sample sizes, variation in bat detection rates and desired statistical power  using automatic bat detectors to monitor populations of bats was explored. A power analysis on  activity data collected with automatic bat detectors indicated that declines in bat populations  would need to be reflected in declines of greater than fifty percent in bat activity before  monitoring programmes would have sufficient power to detect declines in activity. It was  recommended that monitoring programmes should concentrate on intensive presence – absence  surveys rather than long-term studies at a few sites.