Hello Bioacoustics-L
The following articles appeared in the most recent issue if the Journal
of Mammalogy, and can be downloaded at
http://www.uvm.edu/~bmitchel/Bioacoustics.html:
Gorresen, Marcos P., Adam C. Miles, Christopher M. Todd, Frank J.
Bonnaccorso, and Theodore J. Weller. 2008. Assessing bat detectability
and occupancy with multiple automated echolocation detectors. Journal of
Mammalogy, 89(1):11-17.
Abstract: Occupancy analysis and its ability to account for differential
detection probabilities is important for studies in which detecting
echolocation calls is used as a measure of bat occurrence and activity.
We examined the feasibility of remotely acquiring bat encounter
histories to estimate detection probability and occupancy. We used
echolocation detectors coupled to digital recorders operating at a
series of proximate sites on consecutive nights in 2 trial surveys for
the Hawaiian hoary bat (Lasiurus cinereus semotus). Our results
confirmed that the technique is readily amenable for use in occupancy
analysis. We also conducted a simulation exercise to assess the effects
of sampling effort on parameter estimation. The results indicated that
the precision and bias of parameter estimation were often more
influenced by the number of sites sampled than number of visits.
Acceptable accuracy often was not attained until at least 15 sites or 15
visits were used to estimate detection probability and occupancy. The
method has significant potential for use in monitoring trends in bat
activity and in comparative studies of habitat use.
Kazial, Karry A., Sarah Pacheco, and Kristen N. Zielinski. 2008.
Inforamtion content of sonar calls of little brown bats (Myotis
lucifugus): Potential for communication.
Abstract: We examined variability in bat sonar calls related to
characteristics of the caller (i.e., individual identity, sex, state of
lactation, age category, and colony membership) in 2 situations. If
variation in call features reliably reflects characteristics of
individuals, then there is potential for information transfer to
conspecifics. Thus, sonar calls, in addition to their use in orientation
and prey location, may function for communication. We obtained
recordings of sonar calls from 66 little brown bats (Myotis lucifugus)
captured from buildings at Chautauqua Institution, State University of
New York at Fredonia campus, and surrounding areas in 2003–2005. Calls
were recorded using a laptop computer, digitizing card, connector box,
amplifier, and U30 bat detector while the bat crawled from hand to hand
and while in flight. Calls were extracted and analyzed using custom
computer programs to generate measurements for variables describing each
call, which were then analyzed statistically. Our analysis revealed
individual identity, state of lactation, and age category are reliably
indicated by call variation of crawling bats, and individual identity
information is contained in calls of bats in flight. To our knowledge
these results are the 1st report of differences between sonar calls of
lactating and nonlactating individuals for any bat species and
individual differences in sonar calls for M. lucifugus. Individual
identity information is available in calls produced within a situation;
however, this information does not transfer well to the calls of the
same bats produced in different situations. Our results suggest that the
potential for communication of information via sonar calls depends on
calling situation.
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