The Relationship of Body Weight to Overwinter Survival in Columbian Ground Squirrels

Murie, Jan O.; Boag, D. A.

doi:10.2307/1380854

Cited by 126 publications

(88 citation statements)

References 8 publications

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“…Two subclasses of this age class in S. columbianus were found to have different chances of overwinter survival by Murie and Boag (1984). We too found that heavier mass class 2 female young sur vived better than did mass class 1 young (Table 5).…”

Section: The Roles Of Body Mass and Age In Affecting Fecundity And Sumentioning

confidence: 57%

“…Body mass is most often discussed in ground squirrels with regard to timing of immergence into hibernation (Michener 1984b), and body mass can affect squirrel survival. Murie and Boag (1984) found that Columbian ground squirrels (Spermophilus columbianus) with larger fat reserves survived better than lighter animals with smaller fat reserves. This result could be attrib uted to age as well because heavier (and older) S. co lumbianus build deeper and more complex burrows (Shaw 1926).…”

Section: Introductionmentioning

confidence: 98%

“…Body mass correlates with ges tation period, age of maturity, and litter size among North American species of ground squirrels (Armitage 1981), but relationships among life-history characters and body mass within species are only beginning to be examined (Michener 1984a, Murie andBoag 1984). Body mass is most often discussed in ground squirrels with regard to timing of immergence into hibernation (Michener 1984b), and body mass can affect squirrel survival.…”

Section: Introductionmentioning

confidence: 99%

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Uinta Ground Squirrel Demography: Is Body Mass a Better Categorical Variable Than Age?

Sauer¹,

Slade²

1987

Ecology

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Abstract, We compared the relative impact of age and body mass on fecundity and survival in a population of Uinta ground squirrels, and modeled the population using bodymass classes as stage categories in Lefkovitch stage transition matrices. Body mass was a better predictor of survival than was age, and was nearly as good a predictor of litter size. Mass-based stage transition matrices provided results similar to age-based transition ma trices, but also indicated that larger and subsequently more fecund young were a conse quence of a population reduction. We believe that mass-based analysis of ground squirrel populations is a viable alternative to traditional age-based analyses. Body mass is easy to measure in small-mammal populations and is linked to a variety of life-history character istics.

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Section: The Roles Of Body Mass and Age In Affecting Fecundity And Sumentioning

confidence: 57%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Uinta Ground Squirrel Demography: Is Body Mass a Better Categorical Variable Than Age?

Sauer¹,

Slade²

1987

Ecology

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“…Ground squirrels were active only for about 4 months each year, hibernating during the remaining 8 months (Dobson et al 1992;Murie and Harris 1982). Females usually bred within the 1st week after emergence, giving birth 24 days later (Murie and Boag 1984;Murie and Harris 1982). Juveniles emerged, on average, 27 days after birth from the natal burrow and were weaned soon thereafter.…”

Section: Methodsmentioning

confidence: 99%

Timing of Hibernation and Molt in Female Columbian Ground Squirrels

Neuhaus¹

2000

Journal of Mammalogy

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Timing of activity, seasonal changes in food availability, environmental fluctuations, and costs of reproduction are important determinants of an animal's life history. In mountain ground squirrels (Spermophilus), the shortness of the active season influences how they time their activities. I studied timing of the active season, reproduction, and weight loss during hibernation in Columbian ground squirrels (S. columbianus) in Alberta, Canada, from the summer of 1994 to the spring of 1998. Entry into hibernation and emergence from hibernation the following year were earlier for females that did not wean a litter compared with those that did. The active season was shorter and hibernation longer for unsuccessful females than for successful females. Molt of females was earlier when they did not wean a litter than when they did. Date of mating had no influence on success in weaning a litter, but juveniles surviving to yearling age came from litters born earlier than juveniles that did not survive to yearling age. In successfully reproducing females, early entry into hibernation was associated with early mating. Daily and total weight loss during hibernation was higher in females that weaned young than in females that did not wean young.Key words: body mass, ground squirrel, hibernation, molt, reproduction, Spermophilus columbianus Herbivores in temperate zones are faced with a short growing season of plants. Often only 1 season of the year is ideal for raising young, and thus timing of breeding is important for maximizing reproductive success. Because reproduction is energetically costly, parents should try to optimize timing of reproduction to minimize net energy expenditure and maximize investment in offspring. In many birds (Gauthier 1989;Morton and Derrickson 1990;Olsson 1996;Schoech 1996;Verhulst and Tinbergen 1991), black-tailed prairie dogs (Cynomys ludovicianus-Hoogland 1995), Unita ground squirrels (S. armatus-Rieger 1996), and Columbian ground squirrels (S. columbianus-Murie and Harris 1982), ear-* Correspondent: peter neuhaus@hotmail.com ly mating results in higher reproductive success. Many factors affect timing of mating, such as food availability

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“…This rapid learning of appropriate responses is important because up to 30% of juveniles disappear during the first 2 weeks after emerging aboveground at about 1-month of age, presumably due to predation (Mateo, 1996). Predation can account for up to 60% of juvenile S. beldingi mortality (Sherman and Morton, 1984; personal observation) and overwinter survival in some ground squirrels depends on the accumulation of body fat prior to hibernation (Murie and Boag, 1984), thus creating a trade-off between foraging and vigilance (see also Bachman, 1993). In addition to threats from predators, newly emergent juveniles are vulnerable to infanticide by adults and are in the process of becoming nutritionally independent (Sherman, 1982;Mateo, 1996).…”

Section: Introductionmentioning

confidence: 99%

Developmental and geographic variation in stress hormones in wild Belding's ground squirrels (Spermophilus beldingi)

Mateo

2006

Hormones and Behavior

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Extensive research has been conducted on the role of glucocorticoids in regulating growth, mobilizing energy, responding to stressors and modulating learning and memory. However, little is known about the production of corticoids during early development in free-living animals, particularly during sensitive periods of acquisition of important behaviors. In a four-year study of Belding's ground squirrels, Spermophilus beldingi, a non-invasive assay of glucocorticoids was used to quantify age and population differences among juveniles from three California locations. Fecal-cortisol metabolites are elevated during a short period when juveniles first emerge aboveground from their natal burrows at about 4 weeks of age. This period of cortisol elevation coincides with when young are learning survival behaviors such as anti-predator responses and foraging strategies. Population differences in juvenile cortisol levels, which may reflect local variation in habitat quality and predator environments, were not evident until 2 weeks after emergence. Elevated cortisol at the age of emergence was also observed in juveniles born and reared in captivity without exposure to typical stressors that occur around the age of emergence. These results indicate that corticoids are regulated during early development, and the possible functions of age-related corticoid levels are discussed, including mobilization of glucose for natal emergence and later facilitation of growth and energy storage during the short summer before hibernation. In some species, elevated corticoids can also facilitate learning and memory, and current work is exploring whether the higher cortisol observed in all three S. beldingi populations just after emergence function to promote rapid acquisition of survival behaviors.

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The Relationship of Body Weight to Overwinter Survival in Columbian Ground Squirrels

Cited by 126 publications

References 8 publications

Uinta Ground Squirrel Demography: Is Body Mass a Better Categorical Variable Than Age?

Uinta Ground Squirrel Demography: Is Body Mass a Better Categorical Variable Than Age?

Timing of Hibernation and Molt in Female Columbian Ground Squirrels

Developmental and geographic variation in stress hormones in wild Belding's ground squirrels (Spermophilus beldingi)

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