Long-term monitoring of small and medium-sized mammals

Authors(s): B. Miller and H. Harlow

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Publication Date: 0000-00-00

Type: annual report

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Abstract: Objectives Our objective is to establish a long-term monitoring project that will assess the abundance and densities of selected species of mammals at sites representing seven defined vegetation types found in the Grand Teton National Park. The term monitoring implies data collection over multiple years. Taking long term estimations of population composition before, during, and after biotic and abiotic changes provides needed information to assess the impacts of such changes and furnish useful options for management decisions. This standardized monitoring plan will provide information on small and medium-sized mammals that will (1) assess species use of habitat, (2) monitor changes in species composition as a result of environmental change, such as precipitation and temperature, (3) produce predictive models of small and medium-sized mammal distribution based on vegetation type, and (4) analyze the impact of wolf colonization on the mammal (and plant) community. Findings and Status We were able to estimate populations of small mammals in a dry sage plot, a lodgepole pine plot, mixed grass-forb plot, damp sedge-grass meadow, and a sedge-grass swamp. All trapping plots were one hectare grids, and we also recorded indices of medium-sized mammals on those grids. Capture-recapture data were analyzed by the Jolly Seber technique. On the sage plot, we estimated a population of 18 Peromyscous maniculatus and we also captured four individuals of the genus Microtis. In the lodgepole pine grid, sample size was not sufficient to estimate either Clethrionomys gapperi or Eutamius amoenus, the two most common small mammals trapped. In the mixed grasses and forbs, we estimated a population of 55 Microtis and 24 P. maniculatus. In the sedge-grass damp meadow, we estimated a population size for Microtis as 136 individuals. In the sedge-grass swamp, we estimated a population size of 78 Microtis on the 1 ha grid. We recorded indices for medium-sized mammals present on all one hectare grids (in 1999, Tamiasciurus hudsonicus, Thomomys talpoides, Spermophilus spp., Taxidae taxus, Martes americana, Canis latrans, and mouse/vole holes). In year 2000, we will expand our efforts, trapping 7 habitat types with 2 replicates in each type. The 1999 data will be beneficial, but only in the context of repeated sampling over time to demonstrate trends that can be correlated with environmental changes.

Keywords: Grand Teton National Park, animal, mammal, population, habitat, canine, wolf, Canidae, Canis lupus, Peromyscous maniculatus, deer mouse, Microtus, vole, Muridae, Cricetidae, Boreal Redback Vole, Clethrionomys gapperi, chipmunk, Sciuridae, yellow-pine chipmunk, Eutamius amoenus, Tamiasciurus hudsonicus, red squirrel, Thomomys talpoides, pocket gopher, Spermophilus spp, ground squirrel, Taxidae taxus , badger, Mustelidae, Martes americana , marten, Canis latrans, coyote, mouse