Observations of Sympatric Populations of Least Chipmunks (Tamias minimus) and Hopi Chipmunks (Tamias rufus) in Western Colorado, 1995–2006

Jeffrey B Doty,J Jeffrey Root,Charles H Calisher

doi:10.1155/2009/505702

Jeffrey B Doty, J Jeffrey Root + Show 1 more

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https://doi.org/10.1155/2009/505702

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Abstract

From 1995 through 2006, we studied a rodent community in western Colorado, observing weather conditions and their effects on least chipmunk (Tamias minimus) and Hopi chipmunk (T. rufus) populations. There are few studies that have assessed relative abundances of chipmunks over long durations and none have been conducted on least chipmunks or Hopi chipmunks. This study is unique in that it assesses abundances of sympatric populations of these chipmunks over a 12-year period. We captured 116 least chipmunks and 62 Hopi chipmunks during 47,850 trap nights of effort. Results indicated that year-to-year precipitation and temperature fluctuations had little effect on these chipmunk populations. However, the relative abundances of Hopi chipmunks and least chipmunks appear to have an inverse relationship with each other, suggesting the potential for resource competition between these congeners.

Highlights

Numerous and detailed studies have shown that multiple variables contribute to changes in relative sizes of rodent populations
No correlations were found between juniper berry production and fall MNA or the following spring or summer MNA for either species. These data suggest that precipitation and temperature had little effect on populations of least or Hopi chipmunks, 16 20
Least chipmunk Hopi chipmunk Juniper berry index there was an increase in the least chipmunk population in late 2004, when precipitation increased from previous years of this study

Summary

Introduction

Numerous and detailed studies have shown that multiple variables contribute to changes in relative sizes of rodent populations. Among these are availability of food and water [1], variations in seasonal changes [2, 3], competition with other species [4, 5], and the presence of predators [6]. As immediate sources of food and for hoarding, chipmunks of each species harvest seeds and nuts as well as fruits and berries. They include in their diets arthropods and fungi, if supplies of other food sources are not available [8, 9]. When Hopi chipmunks are deprived of water, they will die within about two days [8]

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