Author: Fred LeRoy Knopf
Publisher:
ISBN:
Category :
Languages : en
Pages : 88
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Book Description
This study documents the timing of seasonal events and associated changes in body weights of Uinta ground squirrels (Spermophilus armatus) that live at three different altitudes. The investigation provides detailed field data for biologists investigating circannual rhythms and hibernation in the laboratory. Ground squirrels aroused and subsequently emerged from hibernation in an overlapping sequence: adult males first, followed by adult females, yearling females and yearling males. Within limits some climatic condition(s) delayed emergence and increased the overlap in emergence sequence. The duration of seasonal activities above ground averaged about 90 days for adult and yearling squirrels. Juveniles were active above ground for 60-70 days. Each summer, adult males and adult and yearling females immerged into estivation-hibernation about the same date. Yearling males immerged later and juveniles immerged last. Adult and yearling squirrels gained body weight rapidly except for brief periods during reproduction. Males began to gain weight after the breeding season. Female weights started to increase immediately after emergence but leveled off during lactation. Juveniles gained weight steadily after emergence from the natal burrow. Mean body weights of squirrels leveled off late in the active season. Seasonal activities and changes in body weights of Uinta ground squirrels were shifted back 6 weeks in time at higher elevations. The annual cycle of Uinta ground squirrels appeared to be the result of an interaction between an endogenous timing mechanism and the immediate environmental conditions. Arousal from hibernation occurred about the same date each year and was probably under endogenous control. After arousal, exogenous factors acted to shorten or lengthen subsequent phases in the annual cycle. Later arousal of squirrels at high altitudes indicated that endogenous timing mechanisms of the species are entrained to the environmental conditions encountered at the respective altitudes.
Author: Trixie Nicole Lee
Publisher:
ISBN:
Category : Ecology
Languages : en
Pages : 120
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Book Description
The Artic is home to animals that have taken adaptations to overwintering to extremes. In this dissertation, I have investigated one of these adaptations, hibernation, in two species from the Artic, the Alaska marmot (Marmota broweri) and the artic ground squirrel (Urocitellus parryii). The expression of hibernation under natural conditions in these species was compared by collecting body temperature records of free-living individuals. The Alaska marmot, a highly social species, demonstrated extreme synchrony in body temperature patterns among a family group, indicating a strong reliance on social thermoregulation. In contrast, the artic ground squirrel was confirmed to be a solitary hibernator that reduces body temperature below freezing during torpor. Both species must produce heat when soil temperatures are significantly below freezing for most of the winter. At these subfreezing ambient temperatures, the artic ground squirrel has shown an increasing reliance on nonlipid fuel during torpor, driving a loss of lean mass during hibernation of ~20%. I calibrated deuterium dilation to repeatedly estimate body composition in this species, which dramatically changes adiposity through its annual cycle, and used this technique to quantify lean mass loss throughout hibernation in a study of tissue metabolism. I also developed and applied the natural abundance of nitrogen and carbon stable isotopes as tools for monitoring differential tissue metabolism and differentiating mixed metabolic fuel use in the artic ground squirrel. These data clarified the mechanism of change in nitrogen stable isotopes and indicated that hibernating ground squirrels rebuild organ tissues while breaking down muscle tissue to meet energetic demands. Furthermore, I corroborated a shift in metabolic fuel use toward nonlipid sources during torpor at low ambient temperatures by using the carbon isotope ratio in exhaled breath in combination with respiratory quotient. This dissertation combines studies of hibernation patterns in free-living animals with experimental data on the tissues and fuels being catabolized at very low temperatures to broaden our understanding of how small mammals successfully hibernate in severe weather conditions. It also presents the development and use of stable isotope ratios as physiological tools in hibernating species.
Author: Trixie Nicole Lee
Publisher:
ISBN:
Category : Marmots
Languages : en
Pages : 240
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Book Description
The Arctic is home to animals that have taken adaptations to overwintering to extremes. In this dissertation, I have investigated one of these adaptations, hibernation, in two species from the Arctic, the Alaska marmot (Marmota broweri) and the arctic ground squirrel (Urocitellus parryii). The expression of hibernation under natural conditions in these species was compared by collecting body temperature records of free-living individuals. The Alaska marmot, a highly social species, demonstrated extreme synchrony in body temperature patterns among a family group, indicating a strong reliance on social thermoregulation. In contrast, the arctic ground squirrel was confirmed to be a solitary hibernator that reduces body temperature below freezing during torpor. Both species must produce heat when soil temperatures are significantly below freezing for most of the winter. At these subfreezing ambient temperatures, the arctic ground squirrel has shown an increasing reliance on nonlipid fuel during torpor, driving a loss of lean mass during hibernation of ~20%. I calibrated deuterium dilution to repeatedly estimate body composition in this species, which dramatically changes adiposity through its annual cycle, and used this technique to quantify lean mass loss throughout hibernation in a study of tissue metabolism. I also developed and applied the natural abundance of nitrogen and carbon stable isotopes as tools for monitoring differential tissue metabolism and differentiating mixed metabolic fuel use in the arctic ground squirrel. These data clarified the mechanism of change in nitrogen stable isotopes andd, indicated that hibernating ground squirrels rebuild organ tissues while breaking down muscle tissue to meet energetic demands. Furthermore, I corroborated a shift in metabolic fuel use toward nonlipid sources during torpor at low ambient temperatures by using the carbon isotope ratio in exhaled breath in combination with respiratory quotient. This dissertation combines studies of hibernation patterns in free-living animals with experimental data on the tissues and fuels being catabolized at very low temperatures to broaden our understanding of how small mammals successfully hibernate in severe winter conditions. It also presents the development and use of stable isotope ratios as physiological tools in hibernating species.
Author: Jennie Elizabeth Larkin
Publisher:
ISBN:
Category : Callospermophilus lateralis
Languages : en
Pages : 284
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Author: T. Dic Charge
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
I studied free-living Richardson's ground squirrels (Spermophilus richardsonii) using telemetry and total body electrical conductivity (TOBEC) to evaluate overwinter energy utilization and the impact of seed caching on body composition of males. I excavated 51 hibernation systems and found that 66% of 35 males cached 1 to 4 species of seed in the hivernaculum. Pre-emergent euthermy was shorter for 3 non-caching (0.7 = 0.2 days) than for 13 caching males (4.0 = 2.8 days), and metabolic predictions of overwinter mass loss approximated actual loss for non-caching males, but over-estimated mass loss for caching males. I concluded that caching males recouped some of the mass lost during hibernation by eating the cache during the longer period of pre-emergence euthermy. Based on TOBEC, the recouped mass included both fat and lean tissue. I suggest that caching in one year is a cost of reproduction that offsets the energetic demands of mating the following year.
Author: Jonathan P. Secter
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Author: Robert L. Ruff
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 250
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Author: Steve F. Johnson
Publisher:
ISBN:
Category : Ground squirrels
Languages : en
Pages : 86
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Book Description
Author: David J. Hafner
Publisher: IUCN
ISBN: 9782831704630
Category : Nature
Languages : en
Pages : 188
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Book Description
The first comprehensive treatment of North American rodents of conservation concern. This action plan summarizes the rodent fauna of North America and provides available information on every rodent taxon that has been considered to be of conservation concern by state, provincial and private conservation agencies and regional experts. It is hoped that the survey provided in this action plan will serve as a common ground for all these parties in drawing up conservation strategies for rodents.
Author: Gerhard Heldmaier
Publisher: Springer Science & Business Media
ISBN: 9783540674108
Category : Medical
Languages : en
Pages : 568
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Book Description
This book gives an up-to-date account of the current knowledge of cold adaptation in animals, including phenomena like hibernation, daily torpor, thermoregulation and thermogenesis, metabolic regulation, freeze tolerance, anaerobiosis, metabolic depression and related processes. For the next four years - until the 12th International Hibernation Symposium - it will serve as a state-of-the-art reference source for every scientist and graduate student working in these areas of physiology and zoology.
