The life history and population dynamics of the prairie vole (microtus orchrogaster) on the Cumberland Plateau in Middle Tennessee

The study was conducted on a 28-acre pinetum located near Crossville, Tennessee, on the Cumberland Plateau. The objectives of this study wereI (1) to determine the density and structure of the population of prairie voles (Microtus ochrogaster) on the study area, and (2) to relate indirect sign to population densities of prairie voles. Six one-acre plots were established on the pinetum and a live trapping program was initiated to obtain data for describing the populations. Amounts of indirect sign were obtained from twenty circular plots, two feet in diameter, that were randomly established on each of the plots periodically during the course of study. Field work was begun in December, 1967, and concluded in May, 1969. Population densities varied greatly during the period of study and ranged from 10.00 to 122.50 voles per acre. Variations in density were closely related to the breeding activities of individuals and a highly significant correlation was observed between the percent of adults in breeding condition and fluctuations in population numbers. Seasonal changes in population structure varied with fluctuations in density. Males outnumbered females in most samples and were especially dominant during periods of high levels of sexual activity. The percentages of the different age classes varied during the period of study. Notable increases in the percentage of juveniles were observed following rises in population density after peaks in breeding activity. The average home range size for voles during the study was 0.082 of an acre and no differences in home range size existed between males and females. The overlapping of home ranges was common throughout the study area. The most characteristic sign of vole activity was their systems of runways and tunnels that were utilized by more than one vole at a time. Voles in this study were most active at night. A seasonal variation in weight was observed; mean weights of adults and subadults decreased significantly during the winter months of the study. Voles kept in captivity exhibited growth rates of one gram per day to an age of one month and 0.5 grams per day thereafter, until growth rates leveled off as adulthood was reached. The life spans of all voles were less than one year (x = 139.69 days). A highly significant difference was noted between the mean life span for males (129.62 days) and females (155.05 days). Fleas and lice were the most common parasitic arthropods of the prairie vole in this study. Ticks were less common but were most prevalent on juvenile voles. Examination of blood smears yielded no evidence of parasitic infestation. The percentage of fresh sign found in twenty random samples that were periodically established throughout the study area was a reliable estimate of the relative abundance of the prairie vole. The frequency of fresh sign, such as runways, droppings, and evidence of feeding activity, was significantly related to mean population densities.