Skip to main content Accessibility help

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

  • Orlando A. Schwartz (a1), Kenneth B. Armitage (a2) and Dirk Van Vuren (a3)

Yellow-bellied marmots Marmota flaviventris 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 significantly better survivorship than males beyond the first-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 (Ro) was 0.67, yet the population did not continually decline; adjustments to these data increased Ro to 0.85. Reproductive values (Vx) 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 influence reproduction and survival, by predation, and by movement into and out of the study area.

Corresponding author
All correspondence to: Kenneth B. Armitage, Department of Systematics and Ecology, The University of Kansas, Lawrence, KS 66045-2106, U.S.A. E-mail:
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Journal of Zoology
  • ISSN: 0952-8369
  • EISSN: 1469-7998
  • URL: /core/journals/journal-of-zoology
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed