Microhabitat use by Deer Mice in Response to Fluctuations in Pinyon Mouse Abundance

Abstract

We captured deer mice (Peromyscus maniculatus) and pinyon mice (Peromyscus truei) from October 1994 to October 2005 in an area of sympatry near Molina, west-central Colorado. We examined relative abundances and microhabitat use of these rodents in an area dominated by two major vegetation types: sagebrush (Artemisia spp.) and pinyon-juniper (Pinus edulisJuniperus spp.). This was conducted to assess changes in microhabitat use over time and how these changes relate to the relative abundances of these rodents. Pinyon mouse captures were associated with pinyon-juniper habitat during every year of the study, whereas deer mouse captures were associated with sagebrush habitat during some years but not specifically associated with either habitat type during other years. Generally, when pinyon mouse abundance was relatively low, deer mice were not specifically associated with either habitat. Notably, when deer mouse abundance was relatively low, we captured pinyon mice in sagebrush habitat more often than in years of high deer mouse abundance. Our data suggested that fluctuations in relative abundance in one of these sympatric peromyscine rodents affect microhabitat use of the congener.