scholarly journals Sexual Differences in Reproductive Effort of Richardson's Ground Squirrels

1998 ◽  
Vol 79 (1) ◽  
pp. 1-19 ◽  
Author(s):  
G. R. Michener
Keyword(s):  
Reproductive Effort ◽  
Ground Squirrels ◽  
Sexual Differences

Reproductive effort and costs of reproduction in female European ground squirrels

Oecologia ◽  
1999 ◽  
Vol 121 (1) ◽  
pp. 19-24 ◽  
Author(s):  
Susanne Huber ◽  
Eva Millesi ◽  
Manfred Walzl ◽  
John Dittami ◽  
Walter Arnold
Keyword(s):  
Reproductive Effort ◽  
Ground Squirrels ◽  
Costs Of Reproduction

Differential Costs of Reproductive Effort for Male and Female Richardson's Ground Squirrels

Ecology ◽  
1990 ◽  
Vol 71 (3) ◽  
pp. 855-868 ◽  
Author(s):  
Gail R. Michener ◽  
L. Locklear
Keyword(s):  
Reproductive Effort ◽  
Ground Squirrels ◽  
Male And Female ◽  
Differential Costs

Timing is the only thing: reproduction in female yellow ground squirrels (Spermophilus fulvus)

2014 ◽  
Vol 92 (8) ◽  
pp. 737-747 ◽  
Author(s):  
N.A. Vasilieva ◽  
A.V. Tchabovsky
Keyword(s):  
Litter Size ◽  
Body Condition ◽  
Reproductive Effort ◽  
Individual Characteristics ◽  
Ground Squirrels ◽  
Offspring Survival ◽  
Litter Mass ◽  
Individual Offspring ◽  
Female Survival ◽  
Spermophilus Fulvus

Based on 4-year field observations of yellow ground squirrels (Spermophilus fulvus (Lichtenstein, 1823)), we determined whether female reproductive effort, annual reproductive success, and survival were dependent on age, body condition, time of emergence from hibernation, and previous reproduction. The probability of weaning a litter did not vary with female age, body condition, time of emergence, or previous reproduction. Litter size, litter mass, and offspring survival did not vary with age, whereas individual offspring mass was lower in yearlings than in older females. Body condition upon emergence had no effect on litter size, litter mass, offspring mass, and survival. Reproduction did not influence female survival, physical condition upon emergence next spring, or subsequent reproductive efforts. The only factor that affected the extent of reproductive effort and offspring survival was the date of emergence: the later a female emerged, the lower the total and mean offspring mass, and fewer offspring survived. The modulation of reproduction in female S. fulvus by only the timing of vernal emergence and independent of other individual characteristics can be explained by the high costs of missed reproductive opportunity because of short longevity combined with low costs of reproduction when resources are abundant enough to meet both somatic and reproductive needs.

Sexual differences in over-winter torpor patterns of Richardson's ground squirrels in natural hibernacula

Oecologia ◽  
1992 ◽  
Vol 89 (3) ◽  
pp. 397-406 ◽  
Author(s):  
Gail R. Michener
Keyword(s):  
Ground Squirrels ◽  
Sexual Differences

Growth and its relationship to the initial annual cycle of the golden-mantled ground squirrel, Spermophilus lateralis

1981 ◽  
Vol 59 (6) ◽  
pp. 865-871 ◽  
Author(s):  
John A. Phillips
Keyword(s):  
Litter Size ◽  
Annual Cycle ◽  
Ground Squirrel ◽  
Growth And Development ◽  
Reproductive Effort ◽  
Ground Squirrels ◽  
Active Season ◽  
Spermophilus Lateralis ◽  
Significant Difference ◽  
Two Populations

Thirty-eight litters of golden-mantled ground squirrels (Spermophilus lateralis), from two populations that experienced different lengths of active season, were born and raised in the laboratory. Growth and development in young were inversely related to litter size. Offspring from smaller litters were both able to attain their prehibernation peak of body mass sooner and hibernate after fewer days of homeothermy than squirrels from larger litters. Young that remained homeothermic throughout the initial overwintering period were always from large litters and among the slowest growing littermates. Fecundity was lower in females from the temporally compressed environment. There was no significant difference between populations in the nutrition provided by mothers to their litters. The results suggest that reproductive effort is more conservative in populations of ground squirrels that experience short seasons of activity, yet this conservatism allows the offspring of those populations to reach independence and attain the prehibernation state of preparedness at an earlier age than their counterparts from populations of more moderate climates.

Seasonal patterns and sexual differences in the feeding ecology of arctic ground squirrels (Spermophilus parryii plesius)

1985 ◽  
Vol 63 (6) ◽  
pp. 1298-1301 ◽  
Author(s):  
Ian G. McLean
Keyword(s):  
Feeding Ecology ◽  
Ground Squirrels ◽  
Sexual Differences ◽  
Seasonal Patterns ◽  
Spermophilus Parryii ◽  
Feeding Sites ◽  
Arctic Ground Squirrels ◽  
Selection Of

Arctic ground squirrels (Spermophilus parryii plesius) were studied in southwestern Yukon during the summers of 1977, 1978, and 1979. Samples of feces were collected from every adult captured every 2 weeks in 1978. Legumes were predominant in the diet until the fall, when squirrels switched to Artemisia. Females switched to Artemisia 1 month earlier than males, which correlates with the females' earlier entry into hibernation. Low abundance of legumes in areas in which squirrels preferred to feed indicated that squirrels fed selectively, although proximity of burrows also influenced selection of feeding sites.

Sexual Differences in Body Weight Patterns of Richardson's Ground Squirrels during the Breeding Season

1984 ◽  
Vol 65 (1) ◽  
pp. 59-66 ◽  
Author(s):  
G. R. Michener
Keyword(s):  
Body Weight ◽  
Breeding Season ◽  
Ground Squirrels ◽  
Sexual Differences

Sexual differences in interyear survival and life-span of Richardson's ground squirrels

1989 ◽  
Vol 67 (7) ◽  
pp. 1827-1831 ◽  
Author(s):  
Gail R. Michener
Keyword(s):  
Sex Ratio ◽  
Life Span ◽  
Older Adult ◽  
Litter Size ◽  
Ground Squirrels ◽  
Sexual Differences ◽  
Maximum Life Span ◽  
Southern Alberta ◽  
Males And Females ◽  
Size At Birth

Although equal numbers of males and females were weaned in a population of Richardson's ground squirrels studied in southern Alberta, interyear survival was lower for males than for females in each year of life. Consequently, the sex ratio was biased toward females in both the yearling and older adult cohorts (overall ≤ 23 males per 100 females), and maximum life-span of males was 4 years, whereas that of females was 6 years. Compared with several other species of Spermophilus, Richardson's ground squirrels have a larger litter size at birth and a shorter life-span.

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