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Differences in Townsend's chipmunk populations between second- and old-growth forests in western Oregon

Informally Refereed
Authors: D.K. Rosenberg, R.G. Anthony
Year: 1993
Type: Miscellaneous Publication
Station: Pacific Southwest Research Station
Source: Journal of Wildlife Management. 57(2): 365-373


Because Townsend's chipmunks (Tomias townsendii) may be important in maintaining natural ecosystem processes in forests in the central Oregon Cascade Range, we compared their population characteristics in young second-growth and old-growth forests. We live-trapped Townsend's chipmunks in 5 young (30-60 yr old) second-growth and 5 old-growth (>400 yr old) Douglas-fir (Pseudotsuga menziesii) stands during spring and autumn 1987-90 in western Oregon. We tested the null hypothesis of no difference in characteristics of chipmunk populations in these 2 stand age-classes. Densities ranged from 0.4 to 10.3 chipmunks/ha and were greater (P < 0.05) in old-growth ( ± SE, 5.1 ± 0.4) than in second-growth (2.8 ± 0.3) stands. Chipmunk densities were related to large (≥50 cm diam at breast height [dbh]) snags in old- growth (P = 0.002) but not in second-growth (P = 0.6) stands. Chipmunks in old-growth stands moved shorter (P = 0.03) distances in autumn and had a greater proportion of young-of-the-year (P = 0.007) than those in second-growth stands. These differences suggest that old-growth stands provide better habitat for Townsend's chipmunks than young second-growth stands, and may reflect important functional differences in food chains and energy flow between the different stand age-classes.


Rosenberg, D.K.; Anthony, R.G. 1993. Differences in Townsend''s chipmunk populations between second- and old-growth forests in western Oregon. Journal of Wildlife Management 57(2):365-373