Reproductive Cycle and Litter Size of the Woodchuck

Snyder, Robert L.; Christian, John J.

doi:10.2307/1931796

Cited by 55 publications

(24 citation statements)

References 7 publications

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“…This result contrasted with the pattern in Belding's ground squirrel where litter size increased steadily during years 1±4 and decreased thereafter (Sherman & Morton, 1984). Litter sizes of yearling females was smaller than that of older females in Columbian ground squirrels (Festa-Bianchet, 1981;Festa-Bianchet & King, 1991), Uinta ground squirrels (Slade & Balph, 1974), Wyoming ground squirrels Spermophilus elegans (Pfeifer, 1982), thirteenlined ground squirrels (McCarley, 1966), goldenmantled ground squirrels (Bronson, 1979), Richardson's ground squirrels (Michener, 1980), woodchucks (Snyder & Christian, 1960), and black-tailed prairie dogs (Koford, 1958;Hoogland, 1995). In yellow-bellied marmots the number of female young per litter at ®rst emergence above ground was equal for all age classes.…”

Section: Maternity Patterns and Comparisonsmentioning

confidence: 60%

A 32-year demography of yellow-bellied marmots (Marmota flaviventris)

Schwartz¹,

Armitage²,

Vuren³

1998

J. Zoology

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Yellow-bellied marmots Marmota¯aviventris in the East River Valley of Colorado were live-trapped and individually marked annually from 1962 through 1993. These pooled data were used to produce a demography and life table for these years. Females had signi®cantly better survivorship than males beyond the ®rst-year age class, and the sex ratio became progressively female biased. The major mortality factors of predation and unsuccessful hibernation acted evenly on all age classes as shown by the constant rates of survivorship. The rate of senescence indicated that the probability of mortality did not increase with age. Females produced litters from ages 2 to 10 years. Mean litter size was 4.1 and did not differ among age classes. The female generation length of 4.49 years was 2.4 times the life expectancy and the median survivorship. The net reproductive rate (R o ) was 0.67, yet the population did not continually decline; adjustments to these data increased R o to 0.85. Reproductive values (V x ) were approximately equal across the reproductive age classes. The polygynous mating system is both cause and effect of the demography. Marmot population size is affected by weather factors that in¯uence reproduction and survival, by predation, and by movement into and out of the study area.

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Section: Maternity Patterns and Comparisonsmentioning

confidence: 60%

A 32-year demography of yellow-bellied marmots (Marmota flaviventris)

Schwartz¹,

Armitage²,

Vuren³

1998

J. Zoology

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“…The remaining females remained in their natal area until they were yearlings. Most female woodchucks first reproduce as two year olds [7 of 8 in this study; 47% in Pennsylvania (Snyder and Christian 1960), 74% in New York (Hamilton 1934), 75% in Maryland (Grizzell 1955)]. In yellow-bellied marmots and Olympic marmots, natal dispersal of about 75% of the females also occurs at least one year before most become reproductively mature (Table 3).…”

Section: Interspecific Comparison Of Social Organizationmentioning

confidence: 77%

Social organization of woodchucks (Marmota monax)

Meier

1992

Behav Ecol Sociobiol

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“…In Arctic ground squirrels the mean difference between the first animals to emerge (reproductive males) and the last to emerge (non-reproductive males) is approximately 2 weeks (Buck and Barnes, 1999). Although most marmots are communal hibernators (Arnold, 1993) and arouse closely together (Ruf and Arnold, 2000), woodchucks (M. monax) are solitary hibernators and southern woodchuck (M. monax monax) males arouse 3 weeks before females and subadult males (Snyder and Christian, 1960). The 30-day difference between arousal of male and breeding female echidnas in this study (Table 1), may reflect a requirement for a period of euthermia for spermatogenesis to occur, and also strong selective pressures for males to be active when the first females appear.…”

Section: Timing Of Hibernationmentioning

confidence: 99%

The timing of hibernation in Tasmanian echidnas: why do they do it when they do?1

Nicol

Andersen

2002

Comparative Biochemistry and Physiology Part B: Biochemistry an

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We investigated the patterns of hibernation and arousals in seven free-ranging echidnas Tachyglossus aculeatus setosus (two male, five female) in Tasmania using implanted temperature data loggers. All echidnas showed a 'classical' pattern of mammalian hibernation, with bouts of deep torpor interrupted by periodic arousals to euthermia (mean duration 1.04"0.05 (ns146). Torpor bout length increased as body temperature fell during the hibernation season, and became more variable as temperature rose again. Hibernation started in late summer (February 28"5 days, ns6) and males aroused just before the winter solstice (June 15"3 days, ns3), females that subsequently produced young aroused 40 days later (July 25"3, ns4) while females that did not produce young hibernated for a further two months (arousal Sept 27"5, ns7). We suggest that hibernation in Tasmanian echidnas can be divided into two phases, the first phase, marked by declining minimum body temperatures as ambient temperature falls, appears to be obligatory for all animals, while the second phase is 'optional' and is utilised to varying amounts by females. We suggest that early arousal and breeding is the favoured option for females in good condition, and that the ability to completely omit breeding in some years, and hibernate through to spring is an adaptation to an uncertain climate. ᮊ

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Reproductive Cycle and Litter Size of the Woodchuck

Cited by 55 publications

References 7 publications

A 32-year demography of yellow-bellied marmots (Marmota flaviventris)

A 32-year demography of yellow-bellied marmots (Marmota flaviventris)

Social organization of woodchucks (Marmota monax)

The timing of hibernation in Tasmanian echidnas: why do they do it when they do?1

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