Long-tailed vole (Microtus longicaudus) population outbreaks and refugia after clearcutting of coniferous forests: The search for fluctuations and hotspots

Abstract

AbSTRACT Some species of Microtus voles exhibit multi-annual population fluctuations with peak numbers every 3–5 years, and these periods may be interspersed with annual fluctuations in abundance. Populations of long-tailed voles (M. longicaudus Merriam) increase during the first 3–4 years after clearcutting of coniferous forests, and it is during this population outbreak that voles may feed on newly planted tree seedlings. It is unclear if M. longicaudus has multi-annual population fluctuations similar to other Microtus species, and we do not know the location of refuge habitats during low years of abundance. We describe changes in abundance of M. longicaudus during the first 5–10 years after clearcut harvesting near Golden, British Columbia, Canada, and evaluated four hypotheses (H) that long-tailed voles will (H1) have peak populations at 3–4 years post-harvest, decline to low numbers, with outbreak populations appearing again on newly clearcut sites; (H2) occur at very low ( Long-tailed vole populations increased in abundance on newly clearcut sites and reached independent peak numbers (62, 96, and 134/ha) at 3–4 years post-harvest in three different areas and time periods, thus supporting H1. Long-tailed voles were consistently at very low numbers in uncut forest, and hence this habitat did not provide a refuge or source area for voles, thereby supporting H2. We had some evidence to support H3 that long-tailed voles seemed to persist at low numbers (