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Journal of Comparative Physiology A

, Volume 186, Issue 2, pp 169–180 | Cite as

A circadian pacemaker in free-living chipmunks: essential for survival?

  • P. J. DeCoursey
  • J. K. Walker
  • S. A. Smith
ORIGINAL PAPER

Abstract

The importance of circadian timing was evaluated for 18 months from late-April 1997 through October 1998 in a high-density population of free-living eastern chipmunks, Tamias striatus, at a 4-ha forest site in the Allegheny Mountains. Included in the radio-collared field group were 30 chipmunks with supra-chiasmatic nucleus-targeted lesions, 24 surgical controls, and 20 intact controls. An additional 17 chipmunks were used in a laboratory study as lesion-calibration controls to correlate degree of circadian arrhythmicity with extent of supra-chiasmatic nucleus deletion. Survival was documented in the field by daily radio tracking and by regular trapping censuses except during winter hibernation. A significantly higher proportion of supra-chiasmatic nucleus-lesioned than surgical control chipmunks or intact controls were killed by weasel predation during the first 80 days after repatriation. A 28-h continuous census found no surface activity of any chipmunks during hours of darkness. However, episodes of nocturnal movement were detected within the permanent dens by radio telemetric data logging, especially in supra-chiasmatic nucleus-lesioned animals. Excavation and mapping of six chipmunk burrow systems aided in the interpretation of the telemetric activity data. Nighttime restlessness of supra-chiasmatic nucleus-lesioned animals may have acted as a clue to the predator for locating its prey.

Key words Circadian Rhythms Chipmunk Predation Radio telemetry SCN 

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Copyright information

© Springer-Verlag Berlin Heidelberg 2000

Authors and Affiliations

  • P. J. DeCoursey
    • 1
  • J. K. Walker
    • 1
  • S. A. Smith
    • 2
  1. 1.Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA e-mail: dcoursey@mail.biol.sc.edu Fax: +1-803-777-4002US
  2. 2.Bridgewater College, Bridgewater, VA 22812, USAUS

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