The following articles are in the current issue of the Journal of
Mammalogy. I've downloaded PDFs of the articles described in this
e-mail, and will save them for a few weeks. If list members need
copies, feel free to e-mail me a request.
Magle, Seth, Jun Zhu and Kevin R. Crooks. 2005. Behavioral responses
to repeated human intrusion by black-tailed prairie dogs (Cynomys
ludovicianus). Journal of Mammalogy 86(3):524-530.
Abstract: This study addressed behavioral responses by black-tailed
prairie dogs (Cynomys ludovicianus) to human intrusion in urban and
rural environments in Boulder, Colorado. We expected that if prairie
dogs habituate to repeated disturbances, they should allow a recurring
human intruder to approach closer over time before sounding an alarm
bark or initiating concealment. We also predicted that urban colonies
could be approached more closely than rural colonies before displaying
an avoidance response. Four colonies (2 rural and 2 urban) were
approached >100 times over a 7-month period. Rather than exhibiting
habituation, prairie dogs demonstrated increased responsiveness in
concealment behavior, retreating to their burrows earlier, with
recurring disturbances. Barking distances did not change consistently
with repeated intrusion, but, over time, prairie dogs barked less
frequently when performing their avoidance response, a result with
implications for prairie dog management. Rural colonies had higher
initial concealment distances, and these distances increased more
rapidly with repeated intrusion than did concealment distances in
urban colonies. Thus, rural prairie dogs may be more sensitive to
human intrusion than urban prairie dogs.
Morisaka, Tadamichi, Masanori Shinohara, Fumio Nakahara, and Tomonari
Akamatsu. 2005. Effects of ambient noise on the whistles of
Indo-Pacific bottlenose dolphin populations. Journal of Mammalogy
86(3):541-546.
Abstract: Communication among animals should use signals that are most
efficient in their particular habitat. Here, we report data from 3
populations of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in
Japan that produce whistles transmitted efficiently through
environmental ambient noise. We compared the characteristics of the
ambient noise in the dolphins' habitats and the whistles produced. In
habitats with less ambient noise, dolphins produced whistles at
varying frequencies with greater modulations; when ambient noise was
greater, dolphins produced whistles of lower frequencies with fewer
frequency modulations. Examination of our results suggests that
communication signals are adaptive and are selected to avoid the
masking of signals and the attenuation of higher-frequency
signals. Thus, ambient noise may drive the variation in whistles of
Indo-Pacific bottlenose dolphin populations.
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Brian R. Mitchell
Post-Doctoral Associate
University of Vermont
The Rubenstein School of Environment and Natural Resources
81 Carrigan Drive
Burlington, VT 05405-0088
(802) 656-2496
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