Barbary ground squirrels do not have a sentinel system but instead synchronize vigilance

Electroencephalographic slow-wave activity (SWA) in non-rapid eye movement (NREM) sleep is directly related to prior sleep/wake history, with high levels of SWA following extended periods of wake. Therefore, SWA has been thought to reflect the level of accumulated sleep need. The discovery that euthermic intervals between hibernation bouts are spent primarily in sleep and that this sleep is characterized by high and monotonically declining SWA has led to speculation that sleep homeostasis may play a fundamental role in the regulation of the timing of bouts of hibernation and periodic arousals to euthermia. It was proposed that because the SWA profile seen after arousal from hibernation is strikingly similar to what is seen in nonhibernating mammals after extended periods of wakefulness, that hibernating mammals may arouse from hibernation with significant accumulated sleep need. This sleep need may accumulate during hibernation because the low brain temperatures during hibernation may not be compatible with sleep restorative processes. In the present study, golden-mantled ground squirrels were sleep deprived during the first 4 h of interbout euthermia by injection of caffeine (20 mg/kg ip). We predicted that if the SWA peaks after bouts of hibernation reflected a homeostatic response to an accumulated sleep need, sleep deprivation should simply have displaced and possibly augmented the SWA to subsequent recovery sleep. Instead we found that after caffeine-induced sleep deprivation of animals just aroused from hibernation, the anticipated high SWA typical of recovery sleep did not occur. Similar results were found in a study that induced sleep deprivation by gentle handling (19). These findings indicate that the SWA peak immediately after hibernation does not represent homeostatic regulation of NREM sleep, as it normally does after prolonged wakefulness during euthermia, but instead may reflect some other neurological process in the recovery of brain function from an extended period at low temperature.

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Subtle short-term physiological costs of an experimental augmentation of fleas in wild Columbian ground squirrels

Journal of Experimental Biology ◽

10.1242/jeb.203588 ◽

2019 ◽

Vol 222 (12) ◽

pp. jeb203588

Author(s):

Jeffrey D. Roth ◽

F. Stephen Dobson ◽

François Criscuolo ◽

Pierre Uhlrich ◽

Alexandre Zahariev ◽

...

Keyword(s):

Ground Squirrels ◽

Short Term ◽

Columbian Ground Squirrels

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Effect of climatic conditions on the annual activity and hibernation cycle of Richardson's ground squirrels and Columbian ground squirrels

Canadian Journal of Zoology ◽

10.1139/z77-091 ◽

1977 ◽

Vol 55 (4) ◽

pp. 693-703 ◽

Cited By ~ 34

Author(s):

Gail R. Michener

Keyword(s):

Rocky Mountains ◽

Climatic Conditions ◽

Ground Squirrels ◽

Active Season ◽

Southern Alberta ◽

Annual Activity ◽

The Times ◽

Columbian Ground Squirrels ◽

Spring Emergence ◽

Species Ecology

In 1975 and 1976 the times of spring emergence, breeding, and entry into hibernation were compared for Spermophilus richardsonii and S. columbianus in an area of sympatry in the foothills of the southern Alberta Rocky Mountains. Both species emerged earlier in 1976, which had a warmer than normal spring, than in 1975, which had a cooler than normal spring. In both years S. richardsonii emerged earlier than S. columbianus and remained active longer. Juvenile S. richardsonii entered hibernation when 17–20 weeks old whereas juvenile S. columbianus were 10–11 weeks old. Yearling S. richardsonii bred, whereas yearling S. columbianus did not. Breeding success affected the time of entry into hibernation but not the time of emergence from hibernation in the next spring. A possible relationship between the periodic arousals during hibernation and the emergence pattern of squirrels in spring is discussed. The significance of flexibility of spring emergence, length of the active season, and age at breeding to survival and species ecology is considered.

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The effects of capital on an income breeder: evidence from female Columbian ground squirrels

Canadian Journal of Zoology ◽

10.1139/z05-044 ◽

2005 ◽

Vol 83 (4) ◽

pp. 546-552 ◽

Cited By ~ 25

Author(s):

David R Broussard ◽

F Stephen Dobson ◽

J O Murie

Keyword(s):

Path Analysis ◽

Observational Data ◽

Life Histories ◽

Reproductive Investment ◽

Ground Squirrels ◽

Initial Capital ◽

Spermophilus Columbianus ◽

Live Trapping ◽

Investment In Reproduction ◽

Columbian Ground Squirrels

To maximize fitness, organisms must optimally allocate resources to reproduction, daily metabolic maintenance, and survival. We examined multiple years of live-trapping and observational data from a known-aged population of female Columbian ground squirrels, Spermophilus columbianus (Ord, 1815), to determine the influences of stored resources and daily resource income on the reproductive investments of females. We predicted that because yearling females were not fully grown structurally while producing their first litter, they would rely exclusively on income for reproduction, while reproductive investment in older females (≥2 years of age) would be influenced by both stored resources (capital) and daily income. Results from path analysis indicated that both yearlings and older females were income breeders. However, initial capital indirectly influenced investment in reproduction of yearling and older females. Females with the greatest initial capital maintained high body masses while investing relatively more income in reproduction. By considering influences of both capital and income, important relationships can be revealed between these resources and their influence on life histories.

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