scholarly journals Influence of Habitat on Behavior of Townsend's Ground Squirrels (Spermophilus townsendii)

1998 ◽  
Vol 79 (3) ◽  
pp. 906 ◽  
Author(s):  
Peter B. Sharpe ◽  
Beatrice van Horne
Keyword(s):  
Ground Squirrels ◽  
Spermophilus Townsendii

scholarly journals Two New Species and Temporal Changes in the Prevalence of Eimerians in a Free-Living Population of Townsend's Ground Squirrels (Spermophilus townsendii) in Idaho

1994 ◽  
Vol 80 (2) ◽  
pp. 251 ◽  
Author(s):  
P. G. Wilber ◽  
B. Hanelt ◽  
B. Van Horne ◽  
D. W. Duszynski
Keyword(s):  
New Species ◽  
Temporal Changes ◽  
Ground Squirrels ◽  
Free Living ◽  
Two New Species ◽  
Spermophilus Townsendii

Dispersal patterns of juvenile Townsend's ground squirrels in southwestern Idaho

1998 ◽  
Vol 76 (11) ◽  
pp. 2084-2089 ◽  
Author(s):  
Gail S Olson ◽  
Beatrice Van Horne
Keyword(s):  
Survival Rates ◽  
Habitat Type ◽  
Dispersal Distance ◽  
Ground Squirrels ◽  
Short Term ◽  
Dispersal Patterns ◽  
Conservation Area ◽  
Spermophilus Townsendii ◽  
Dispersal Distances ◽  
Two Parameter

Understanding the effects of habitat reduction or fragmentation on animals requires some knowledge of their dispersal patterns. We used radiotelemetry to examine dispersal characteristics of 59 (37 male and 22 female) juvenile Townsend's ground squirrels (Spermophilus townsendii) on the Snake River Birds of Prey National Conservation Area in southwestern Idaho from April to June in 1993 and 1994. We tested for differences between years, sexes, and habitats in the rates and distances of dispersal. We compared the fates of dispersers and nondispersers and tested whether the direction of dispersal differed from random and whether the distribution of dispersal distances could be fitted to a two-parameter exponential function. Of the 38 animals for which dispersal status could be determined, 16 dispersed. The proportion of dispersers was greater for males than for females, but these rates did not differ by year or habitat type. We found no differences between habitats in dispersal distance. Survival rates through immergence into estivation did not differ between dispersers and nondispersers, suggesting that dispersal is not risky over the short term. Direction of dispersal did not differ from random, and the distribution of dispersal distances was adequately fitted to a truncated exponential distribution with a truncation distance of 118 m. Dispersers tended to end up in the habitat type that they started in, suggesting the possibility of habitat imprinting.

Can shrub cover increase predation risk for a desert rodent?

1996 ◽  
Vol 74 (1) ◽  
pp. 157-163 ◽  
Author(s):  
Robert L. Schooley ◽  
Peter B. Sharpe ◽  
Beatrice Van Horne
Keyword(s):  
Predation Risk ◽  
Activity Patterns ◽  
Ground Squirrels ◽  
Shrub Cover ◽  
Vegetative Cover ◽  
Predator Detection ◽  
Desert Rodents ◽  
Spermophilus Townsendii ◽  
Ceratoides Lanata ◽  
One Year

Previous research indicates that predation risk may influence activity patterns, habitat partitioning, and community structure of nocturnal desert rodents. Shrub microhabitat is typically considered safer than open microhabitat for these small mammals. We investigated predation risk for Townsend's ground squirrels (Spermophilus townsendii), which are diurnal desert rodents that detect predators visually and use burrows for refuge. Our results suggested that shrub cover may increase risk for these squirrels by decreasing their ability to escape from predators. Our field experiment indicated that running speeds of juvenile squirrels were lower in shrub (Ceratoides lanata) habitat than in open areas. Shrub cover was also associated with shorter predator-detection distances (mammalian and avian) and fewer refuges (burrow entrances per hectare) than in open areas in one year but not in another. Our study demonstrated that the visual and locomotive obstruction of vegetative cover may increase predation risk for diurnal desert rodents and that elements of habitat-dependent risk may be temporally dynamic.

scholarly journals Bottlenecks and rescue effects in a fluctuating population of golden-mantled ground squirrels (Spermophilus lateralis)

2010 ◽  
Vol 12 (1) ◽  
pp. 285-296 ◽  
Author(s):  
Mary Brooke McEachern ◽  
Dirk H. Van Vuren ◽  
Chris H. Floyd ◽  
Bernie May ◽  
John M. Eadie
Keyword(s):  
Ground Squirrels ◽  
Spermophilus Lateralis

scholarly journals Suprachiasmatic Nucleus and Photic Entrainment of Circannual Rhythms in Ground Squirrels

1991 ◽  
Vol 6 (4) ◽  
pp. 315-330 ◽  
Author(s):  
Theresa M. Lee ◽  
Irving Zucker
Keyword(s):  
Suprachiasmatic Nucleus ◽  
Ground Squirrels ◽  
Photic Entrainment

Sleep after arousal from hibernation is not homeostatically regulated

1999 ◽  
Vol 276 (2) ◽  
pp. R522-R529 ◽  
Author(s):  
Jennie E. Larkin ◽  
H. Craig Heller
Keyword(s):  
Sleep Deprivation ◽  
Brain Function ◽  
Extended Period ◽  
Nrem Sleep ◽  
Wave Activity ◽  
Ground Squirrels ◽  
Recovery Sleep ◽  
Sleep Homeostasis ◽  
Homeostatic Response ◽  
Periodic Arousals

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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