Publications

Manipulative experimentation that features random assignment of treatments, replication, and controls is an effective way to determine causal relationships. Wildlife ecologists, however, often must take a more passive approach to investigating causality. Their observational studies lack one or more of the 3 cornerstones of experimentation: controls, randomization, and replication. Although an obse

Based on 168 records of both verbal descriptors of White-tailed Deer (Odocoileus virginianus) femur-marrow fat and percentage of fat measured later, "gelatinous" served well to distinguish fat < 46% from higher percentages. "Waxy" distinguished fat > 56%.

We examined the spatial interactions of nine female White-tailed Deer (Odocoileus virginianus) in two deeryards (winter aggregations) in northeastern Minnesota during February-April 1999. Global positioning system (GPS) collars yielded seven pair-wise comparisons of deer that were located at the same time (???1 minute apart) and mat used overlapping areas. Deer traveled separately and did not asso

Weights of 118 female and 141 male Minnesota Wolves (Canis lupus) aged 2-24 months increased almost linearly from about 8 kg for females and 10 kg for males at 3 months to 30 kg for females and 32 kg for males at 10-12 months and then tended to increase much more slowly in an overall curvilinear trend. Considerable variation was apparent for both sexes during their first year.

Examination of 110 Mink (Mustela vison) carcasses from 1998 through 2007 indicated that the giant kidney worm, Dioctophyma renale, occurred in Pine and Kanabec Counties of eastern Minnesota with annual prevalences of 0-92%. Worm prevalence increased from 20% in 1999 to 92% in 2001 and decreased to 6% in 2005. During 2000 to 2007, no worms were found in Mink from Anoka and Chisago Counties (n = 54)

The failure of managed wetlands to provide a broad suite of ecosystem services (e.g., carbon storage, wildlife habitat, ground-water recharge, storm-water retention) valuable to society is primarily the result of a lack of consideration of ecosystem processes that maintain productive wetland ecosystems or physical and social forces that restrict a manager's ability to apply actions that allow thos

Within the United States, the Dakota Skipper now occurs only in Minnesota, North Dakota, and South Dakota. In these states it has been associated with margins of glacial lakes and calcareous mesic prairies that host warm-season native grasses. Preliminary geographic information system (GIS) analysis in North Dakota has indicated a close congruency between historic distribution of the Dakota Skippe

Invasibility is a critical feature of ecological communities, especially for management decisions. To date, invasibility has been measured in numerous ways. Although most researchers have used the richness (or number) of exotic species as a direct or indirect measure of community invasibility, others have used alternative measures such as the survival, density, or biomass of either a single or all

No abstract available.

We investigated the relationship between grassland breeding bird densities and both grazing and available moisture in the central Platte River Valley. Nebraska between 1980 and 1996. We also compared species richness and community similarity of breeding birds in sedge (Carex spp.) meadows and mesic grasslands. Densities of two species had a significant relationship with grazing and six of seven fo

Three flea beetle species (Aphthona spp.), first introduced into North America in 1988, have come to be regarded as effective biological control organisms for leafy spurge (Euphorbia esula). The black flea beetles (Aphthona lacertosa and A. czwalinae) in particular have been shown to cause reductions in leafy spurge stem counts in the northern Great Plains, while the brown flea beetle (A. nigriscu

Eliminated from North Dakota's prairies by the mid-1900s, the return of the swift fox to its native habitat has been anything but speedy. Biologists are finally seeing the first signs of this diminutive animal's homecoming.