Gestation Period of the Woodchuck, Marmota monax

Hoyt, Southgate Y.; Hoyt, Sally F.

doi:10.1093/jmammal/31.4.454

Cited by 6 publications

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“…The use of EIAs to detect pregnancy was confirmed, as eight hormone cycles classified as pregnant profiles were followed by the production of viable pups. Gestation in this species appears to be 34 days from peak breeding activity or 32 days from estimated ovulation, similar to the gestation of woodchucks at 31–32 days [Concannon et al, ; Grizzell, ; Hoyt and Hoyt, ; Snyder and Christian, ] and alpine marmots at 37 days [Exner et al, ].…”

Section: Discussionmentioning

confidence: 61%

“…Similar behavioral patterns have been observed in other marmot species. For example, Hoyt and Hoyt [] observed a great deal of “boxing” behavior between adult woodchucks which occurred during the mating season, decreasing into the active season. Barash [] observed more play‐fights between adult breeding pairs during the first few weeks posthibernation than later in the season in both yellow‐bellied and hoary marmots, confirming our observations.…”

Section: Discussionmentioning

confidence: 99%

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The reproductive endocrinology and behavior of Vancouver Island marmot (Marmota vancouverensis)

et al. 2011

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The Vancouver Island marmot (Marmota vancouverensis; VIM) is one of North America's most endangered species with fewer than 150 individuals remaining in the wild. A captive breeding program was established across four facilities in Canada as an insurance population and source of animals for reintroduction to the wild. The purpose of this study was to gather information about the basic reproductive biology and behavior of this species, which is essential to improve captive breeding programs. Regular fecal samples were obtained from adult female (n = 14) and male (n = 10) marmots, 2 years of age and older, over 1-3 breeding seasons (2-3 months duration posthibernation) for steroid hormone analysis. Enzyme immunoassays were validated for quantifying fecal testosterone metabolite concentrations for males, and fecal estrogen and progesterone metabolite concentrations for females. Results indicated that fecal progesterone metabolite concentrations can be used to monitor ovulation and pregnancy. Behavioral monitoring through infrared video surveillance was conducted in four breeding pairs over a 2-year period (n = 7 behavioral profiles). Breeding behaviors correlated strongly with changes in reproductive endocrine profiles. A high frequency of play behavior or "wrestling" was observed in conjunction with breeding activity before an elevation in progesterone metabolite concentrations. Impending parturition was associated with increased aggression and exclusion of the male from the maternal nestbox as well as an increase in nesting activity. Observational data combined with hormonal analysis suggest that female VIMs are induced ovulators and that multiple breeding attempts may be required for ovulation and conception. Gestation appears to be approximately 34 days from peak breeding activity (32 days from estimated ovulation). Fecal testosterone concentrations suggest that testicular activity is seasonal with the reproductive activity occurring immediately posthibernation. Monitoring breeding behavior is a useful means of indicating estrus, conception and pregnancy, which can also be supported by the hormonal analysis of daily fecal samples of individual animals.

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Section: Discussionmentioning

confidence: 61%

Section: Discussionmentioning

confidence: 99%

The reproductive endocrinology and behavior of Vancouver Island marmot (Marmota vancouverensis)

et al. 2011

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Sociality as a life-history tactic of ground squirrels

1981

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Multi-variate analysis of life-history traits of 18 species of burrowing sciurids indicates that reproductive effort is determined by body-size energetics. Other traits, such as age adult weight reached, age of dispersal, length of time of gestation, were significantly correlated with body size. A principal component analysis suggested that the complex of life-history traits could be reduced to four components: body size (=weight), seasonality, specific reproductive effort, and maturity. The variation in the sociality index was best explained by age of first reproduction and age adult weight reached. Generally, species are more social when large body size combined with a relatively short growing season is associated with delayed dispersal and occurs in those species typically breeding for the first time at age two or older. Sociality in these species may have evolved through retention of daughters within the maternal home range as a means of continuing reproductive investment beyond weaning.

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A review of molt in mammals, with an emphasis on marmots (Rodentia: Sciuridae: Marmota)

Mills,

Brandler,

Olson

2024

Journal of Mammalogy

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Molting is an evolutionarily ancient trait in which the outermost layer of an organism is replenished, usually according to a regular circannual rhythm. It is a metabolically costly process and, in vertebrates, is generally timed around other energetically demanding events such as reproduction and migration. In mammals, molting involves replacement of the fur coat—one of the most distinct innovations of the mammalian lineage. Despite the obvious importance of hair to mammalian fitness, our knowledge of hair growth cycles, circannual molting patterns, and hair structure remains largely restricted to marine and domesticated mammals, and our ability to identify explicit adaptive advantages of molting strategies in any mammal is therefore limited. In this review, we summarize what is known of these topics in wild, terrestrial mammals with a particular emphasis on marmots (Marmota spp.). Marmots are the largest extant ground squirrels and are well adapted to seasonally cold environments. Molting may be particularly relevant to fitness in marmots given the presumed importance of a healthy, insulative coat for metabolic efficiency in cold environments. Moreover, marmots hibernate for 7 to 8 months each year, meaning the annual molt and all other energetically demanding life-history events (such as parturition, lactation, fat accumulation, and dispersal) are constrained to an active period of only 4 to 5 months. Because the energetics of hibernation, fat accumulation, reproduction, and social behavior are already well studied, examining how molt is timed with respect to other important events and how it is influenced by local conditions may inform how molting is prioritized and how molting strategies evolve under specific selective pressures.

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Gestation Period of the Woodchuck, Marmota monax

Cited by 6 publications

References 0 publications

The reproductive endocrinology and behavior of Vancouver Island marmot (Marmota vancouverensis)

The reproductive endocrinology and behavior of Vancouver Island marmot (Marmota vancouverensis)

Sociality as a life-history tactic of ground squirrels

A review of molt in mammals, with an emphasis on marmots (Rodentia: Sciuridae: Marmota)

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