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. ---------------------------------------------------------- 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 [EMAIL PROTECTED] ----------------------------------------------------------
