Population Dynamics of Deer Mice, Peromyscus maniculatus, and Yellow-pine Chipmunks, Tamias amoenus, in Old Field and Orchard Habitats

There are often several rodent species included in the small mammal communities in orchard agro-ecosystems. This study was designed to test the hypothesis that the population levels of Deer Mice (Peromyscus maniculatus) and Yellow-pine Chipmunks (Tamias amoenus) would be enhanced in old field compared with orchard habitats. Rodent populations were intensively livetrapped in replicate old field and orchard sites over a four-year period at Summerland, British Columbia, Canada. Deer Mouse populations were, on average, significantly higher (2.5 – 3.4 times) in the old field than orchard sites in summer and winter periods. Mean numbers/ha of Deer Mice ranged from 12.1 to 60.4 in old field sites and from 3.3 to 19.9 in orchard sites. Breeding seasons in orchards were significantly longer than those in old field sites, in terms of proportion of reproductive male Deer Mice. Recruitment of new animals and early juvenile survival of Deer Mice were similar in orchard and old field sites. Populations of Yellow-pine Chipmunks ranged in mean abundance/ha from 5.6 – 19.0 in old field sites and from 1.9 – 17.5 on one orchard site, with no difference in mean abundance in 2 of 4 years of the study. Recruitment and mean survival of Yellow-pine Chipmunks also followed this pattern. This study is the first detailed comparison of the population dynamics of these rodent species in old field and orchard habitats. These species should be able to maintain their population levels and help contribute to a diversity of small mammals in this agrarian landscape

Impact of orchard vegetation management on small mammal population dynamics and species diversity

Voles of the genus Microtus feed on bark and vascular tissues of trees in fruit orchards across North America. Management of orchard floor vegetation with multiple applications of herbicide effectively altered habitat and reduced montane vole (M. montanus) populations in apple orchards near Summerland, British Columbia, Canada. Non-target populations of deer mice (Peromyscus maniculatus), northwestern chipmunks (Tamias amoenus), and Great Basin pocket mice (Perognathus parvus) appeared to respond positively to the treatment units. None of these non-target species was adversely affected by the actual herbicide treatments. Species diversity of small mammal communities in treated orchards was the same as that in untreated orchards and nearby old fields. Orchard agroecosystems with intensive vegetation management regimes appear to maintain diverse non-target small mammal communities

Impact of orchard vegetation management on small mammal population dynamics and species diversity

Voles of the genus Microtus feed on bark and vascular tissues of trees in fruit orchards across North America. Management of orchard floor vegetation with multiple applications of herbicide effectively altered habitat and reduced montane vole (M. montanus) populations in apple orchards near Summerland, British Columbia, Canada. Non-target populations of deer mice (Peromyscus maniculatus), northwestern chipmunks (Tamias amoenus), and Great Basin pocket mice (Perognathus parvus) appeared to respond positively to the treatment units. None of these non-target species was adversely affected by the actual herbicide treatments. Species diversity of small mammal communities in treated orchards was the same as that in untreated orchards and nearby old fields. Orchard agroecosystems with intensive vegetation management regimes appear to maintain diverse non-target small mammal communities