Behavioral and environmental factors in the spatial distribution and population dynamics of a yellow—bellied marmot (Marmota flaviventris) population were studied in 1971 and 1972 in Gunnison Co., Colorado. Yellow—bellied marmots are generally considered to be colonial; however, this is not their only option, depending upon the marmots' behavioral profile and the size and composition of the habitat. Of the adult—yearling group 75% lived as members of colonies, 16% lived at satellite sites, and 8% were transients. Satellite sites differed from colonies mainly in size and topographic diversity; they may be considered mini—habitats, with the most limited resources being burrow sites. Marmots can be classified, by means of mirror—image stimulation (MIS), as aggressive, social, and avoider. Aggressive females tended to occupy small harems at large sites, or to live as solitary individuals regardless of the size of the site. Social females occurred primarily at large sites, in harems. Avoider females lived in peripheral burrows at colonies, or in satellite sites. All behavioral types reproduced successfully, but reproductive fitness was correlated with social structure. Aggressive females were most fit in small harems or at satellite sites, whereas social females were most fit in large social groups. Avoiders were least fit in all social situations. Data presently available fails to show that the behavioral profile of the female is reflected in the social tendencies of her young. In general, social behavior is a major factor affecting the distribution and dynamics of populations of yellow—bellied marmots, but dispersion is also related to the distribution of suitable habitat.
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ABSTRACT:Seasonal changes in the body weights of yellow-bellied marmot (Marmota flaviventris) populations were studied for 8 years in western Colorado. Marmots may be classified by size into four age groups: juvenile, yearling, 2-year-old, and 3-year-old or older, each group with significantly different mean body weights. For each age group, the mean body weight of males was significantly larger than that of females. Mean body weights in June of yearlings and older were smaller, the later the onset of the growing season. All age groups made significant weight gains each year; there was no significant difference in growth rates among years. When the rates of weight gain of juveniles are corrected for time of appearance aboveground, the regression coefficients are virtually identical. The earlier young marmots are weaned, the more they weigh at hibernation and the more likely they are to survive hibernation. The percentage of young surviving their first winter of hibernation is significantly greater the earlier spring begins. Marmots at 3400 m elevation had growth -rates similar to those of marmots at 2900 m elevation.The adaptive strategy of marmots includes rapid growth rates, high tissue growth efficiencies and extension of the growing season by reproducing immediately following hibernation.
Abstract. Twenty-nine adult and yearling marmots were exposed to mirror-image stimulation. Marmots interacted intensely with their image, and the frequency of occurrences of 22 behaviors was recorded. The four factors extracted from the behavioral data by factor analysis accounted for 88% of the total variance. Three factors were interpretable and designated "approach," "avoidance," and "sociability." Behavioral patterns were stable over time and repeatable. A plot of "avoidance" against "sociability" provides a visualization of the numerical behavioral profile of each animal which is consistent with and interpretable in terms of behavioral patterns observed in the field.
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