Multiple scan tomography to assess bat roost cavities

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I request funds to purchase a PiCUS Sonic Tomograph (PiCUS 10 Bluetooth unit) made by Argus Electronic GMBH.  Tomography represents the most accurate way to acquire three dimensional images of the internal structure of live or dead trees, specifically tree cavities used by roosting bats and birds. Tomography assesses the structure of trees quantitatively and most importantly for our studies, non-destructively. The data collected will be used to quantify the volume and structure of cavities used by bats and birds. We predict that cavity-specific features, with attributes more subtle than we have been able to assess, form the basis for roost site selection by bats. This hypothesis is being tested by a current MSc student but given that our work occurs in a park and there are a limited number of trees used by bats, destructive sampling is not possible. The purpose of a subsequent MSc project will be to measure metabolism by free-ranging bats.  While telemetry enables us to assess when individuals use torpor, precise estimates of the actual energy savings are not possible without field metabolic measurements.  By knowing the volume of cavities and the number of individuals in them on any given day, we can use air samples from cavities to make precise measurements of oxygen turnover and hence metabolism. The tomograph will also be used to make annual measurements on known cavities to assess decay rate.  This coupled with data on cavity use by bats between years will allow for predictions about the longevity of cavities as resources for bats and thus the rate at which new cavities must be recruited to maintain stable bat populations.