New Zealand Journal of Zoology abstracts
Influence of winter weather conditions on lesser short-tailed bat (Mystacina tuberculata) activity in Nothofagus forest, Fiordland
J. E. Christie*
Department of Zoology
University of Otago
P.O. Box 56
Dunedin, New Zealand
W. Simpson
Department of Conservation
P.O. Box 29
Te Anau, New Zealand
*Address for correspondence:
Research, Development & Improvement, Department of Conservation,
P.O. Box 13 049, Christchurch, New Zealand.
jchristie@doc.govt.nz
Abstract Winter activity of the New Zealand lesser short-tailed bat (Mystacina tuberculata) was monitored in temperate beech (Nothofagus)
rainforest in Fiordland during winter in 1997 and 1998. Thirty-three
full nights (486 h) were sampled using automatic bat detector
units at 12 sites. Activity was detected on 18 nights (264 bat passes
total, on 54.5% of nights). Index counts (bat passes per night, and
passes per hour) were low and highly variable, implying larger sample
sizes are needed before more precise estimates of activity levels can
be attempted. A logistic regression model indicated that the
probability of bats being active in winter increased with overnight
mean temperature, and if it was raining. Dusk temperature, minimum
overnight temperature, moon visibility, and significant cloud cover
were excluded from the final model. Lesser short-tailed bats were still
active down to –1.6°C, a lower temperature than is tolerated
by many other bat species reliant on flying insects. The observed
winter activity followed a pattern of nights with low or no activity
interspersed with nights of high activity. This is consistent with
patterns observed in other lesser short-tailed bat populations,
although in the Eglinton Valley, they were generally less active over
the winter months. We suggest variation in winter activity levels
between populations is most likely driven by climate, the quality of
foraging habitat, and the physiological constraints of body size on
torpor.
Keywords bats; winter; Mystacinidae; hibernation; activity patterns; foraging; New Zealand
Z06007; Received 15 July 2005; accepted 5 April 2006; Online publication date 19 April 2006
New Zealand Journal of Zoology, 2006, Vol. 33: 133–140
0301–4223/06/3302–0133 © The Royal Society of New Zealand 2006
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