Vallance, Noa Hammes (2022) Physiological ecology of free-living golden-mantled ground squirrels (Callospermophilus laterlias) before and during hibernation. Masters thesis, Northern Arizona University.
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Abstract
To some extent, the annual biological cycle of free-living hibernators reflects local environmental conditions. The golden-mantled ground squirrel (Callospermophilus lateralis, GMGS), an obligate hibernating ground squirrel, is exposed to a range of conditions across its wide range; yet, the majority of studies on this model hibernator have been undertaken under laboratory conditions and there have been far fewer studies of free-living populations. To better understand how behavior and physiology of free-living GMGSs integrates with environmental conditions, I investigated seasonal patterns of above ground presence and body temperature (Tb) in a previously unstudied population in northern Arizona in relation to phase of the annual cycle and environmental conditions. In one chapter, I investigated above ground activity and Tb in the months prior to hibernation and the integration of those patterns with sex, environmental conditions, and survivorship. In another chapter, I characterized the phenology and Tb of the hibernation season in adult females in the context of geographical location.I found that, in the months prior to hibernation, free-living GMGSs structure the timing of above ground presence to certain patterns of light and temperature but modify the duration and timing of above ground presence when the thermal environment is energetically costly, particularly on humid days. As hibernation approaches, animals reduce time spent above ground and decrease mean and minimum Tb. Animals that survived the active season and were able to enter hibernation spent less time above ground and decreased Tb more rapidly and more than animals that died prior to entering hibernation, and these changes began about four weeks prior to hibernation onset. Confirmed survivorship was low (less than 12%) and was possibly related to drought, which likely precluded animals from reaching the adiposity threshold required for hibernation and caused animals to increase time above ground per day extend the duration of the active season. In the animals that survived and entered hibernation, all adult females, I was further able to characterize hibernation phenology and over-winter Tb patterns. I found that adult female GMGSs in northern Arizona exhibit a hibernation season of approximately 7 months, most of which is spent torpid, and resume above ground activity within 1-2 days of terminating heterothermy. Tb generally tracked Tsoil, and animals reached a minimum torpid Tb of 1.5 - 2°C. Seasonal patterns of torpor duration and torpid Tb from the northern Arizona population were comparable to published results of this and other free-living ground squirrel species and reflect geographical trends.
Item Type: | Thesis (Masters) |
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Publisher’s Statement: | © Copyright is held by the author. Digital access to this material is made possible by the Cline Library, Northern Arizona University. Further transmission, reproduction or presentation of protected items is prohibited except with permission of the author. |
Keywords: | activity; behavior; body temperature; Golden-mounted ground squirrel; hibernation; physiology; Arizona |
Subjects: | Q Science > QL Zoology |
NAU Depositing Author Academic Status: | Student |
Department/Unit: | Graduate College > Theses and Dissertations College of the Environment, Forestry, and Natural Sciences > Biological Sciences |
Date Deposited: | 01 Jun 2023 17:00 |
Last Modified: | 01 Jun 2023 17:00 |
URI: | https://openknowledge.nau.edu/id/eprint/5940 |
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