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An
Original Method for Remotely Recording Bat Activity in the Field
Using Automated Ultrasound Recorders: Applications in Research
and Conservation.
DPhil
research degree.
Effective
bat conservation relies in part, on being able to identify species,
quantify their distributions and patterns of habitat use. Many
bats emit species-specific echolocation calls with distinctive
frequency parameters. Therefore, one way of monitoring bats in
the field is by recording their echolocation calls. Previous research
on bats has often involved the use of many people, walking transects
for a few hours after sunset with hand-held bat detectors. Frequently,
identification of bats relies on the experience of the observer.
Some habitats, particularly those dangerous or impossible to traverse
at night are under sampled. Furthermore, unless the whole night
is sampled, activity is also likely to be under sampled.
This
thesis describes the Automated
Ultrasound Recorder (AUR), a method for automatically recording
bat vocalisations and the time at which they were recorded, without
the need for human presence. Therefore, the bat's natural behaviour
is not affected. The recorded calls can be assigned to species
by analysis of their call parameters, and provide measures of
bat activity. The system can be operated and maintained by one
person. By using several AURs, different areas can be sampled
simultaneously. The AUR can also be positioned during the day
in places that are impossible to reach in the dark (e.g. dense
woodland, or just below the canopy).
The
applications for the AUR in bat research and conservation were
tested at Ebernoe
Common in West Sussex. AURs were used to quantify differences
in bat activity in various woodland habitat types, assess differences
in bat activity at different heights in the canopy, to record
calls outside Myotis bechsteinii maternity roosts. Evidence for
spatial and temporal differences in bat activity between habitat
types and sampling heights were found. Previously unreported calls
were recorded for Myotis bechsteinii.
Links
to various chapters will appear here for those interested.
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