Do changes in berry crops drive population fluctuations in small rodents in the southwestern Yukon?

A significant portion of population fluctuations in small rodents within boreal forest ecosystems can be attributed to variations in berry crops, mushrooms, and tree seeds. This study, conducted over 13 years (1997–2009) in the Kluane Lake region of southwestern Yukon, Canada, found that 78–98% of the variation in the abundance of red-backed voles, deer mice, and field voles could be explained by indices of berry crops and mushrooms from the previous summer. Specifically, berries of Empetrum nigrum were critical for red-backed vole populations, while Arctostaphylos uva-ursi, A. rubra, and mushrooms were key predictors for deer mice. Spruce seed crops did not significantly correlate with rodent densities or changes in density. The study supports the bottom-up hypothesis, suggesting that overwinter survival of rodents is closely tied to the availability of food resources from the previous year.

Krebs, C. J., Cowcill, K., Boonstra, R., & Kenney, A. J. (2010). Do changes in berry crops drive population fluctuations in small rodents in the southwestern Yukon? Journal of Mammalogy, 91(2), 500–509. https://doi.org/10.1644/09-mamm-a-005.1