Abstract # 2706 Event # 121:

Scheduled for Sunday, September 20, 2009 05:10 PM-05:30 PM: Session 11 (Mission Bay Ballroom AB) Symposium


HEARING, HOWLING, AND HOLLYWOOD: AUDITORY SENSITIVITY IN ALOUATTA PALLIATA IS ATTUNED TO HIGH-FREQUENCY INFANT DISTRESS CALLS.

M. A. Ramsier1, K. E. Glander2, J. J. Finneran3, A. J. Cunningham1 and N. J. Dominy1
1University of California, Department of Anthropology, Santa Cruz, CA 95064, USA, 2Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, 3U.S. Navy Marine Mammal Program, SSC Pacific, San Diego, California 92152
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     Howling monkeys are celebrated for their low-frequency loud calls or roars. Such vocalizations are hypothesized to be central to the socioecology of howlers; however, data gathered via the auditory brainstem response method indicates that the auditory sensitivity of mantled howling monkeys, Alouatta palliata, is poorly attuned to low frequencies. In fact, among adult howlers (n=8), the frequency region of best auditory sensitivity is unexpectedly high, ca. 8-16 kHz. Interestingly, distress calls emitted from of an infant Alouatta palliata at La Pacifica contain harmonics at and above 14 kHz, which corresponds well to the frequency region of best auditory sensitivity. To explore the significance of relationships between auditory sensitivity, infant vocalizations, and infant-adult interactions in Alouatta, we approached Hollywood special effects artists to construct a lifelike scale model of an infant mantled howler with a speaker imbedded in the abdomen. Field experiments with this model will include exploring the effects of altering the infant call to omit the high or low frequency components. The challenges and benefits of this approach are discussed with an eye toward understanding the evolution of acoustic communication and infant-adult interactions in Alouatta palliata and other species.