Publications

No abstract available.

Crayfish are not native to the Colorado River basin (CRB), however they are now established in portions of the mainstem and in many tributaries. I used density manipulation experiments in a laboratory setting to determine intra- and interspecific competition for food between Orconectes virilis, an aggressive polytrophic crayfish now common in the CRB, and two native fishes: Gila chub...

I analyzed annual height growth and survivorship of Fremont cottonwood (Populus fremontii S. Watson) saplings on three floodplains in Colorado and Utah to assess responses to interannual variation in flow regime and summer precipitation. Mammal exclosures, supplemented with an insecticide treatment at one site, were used to assess flow regime – herbivore interactions. Multiple regression...

Mechanical predator removal programs have gained popularity in the United States and have benefited the recovery of several native trout and spring fish. These successes have been limited to headwater streams and small, isolated ponds or springs. Nevertheless, these same approaches are being applied to large river systems on the belief that any degree of predator removal will somehow...

We analyzed the transverse pattern of vegetation along a reach of the Fremont River in Capitol Reef National Park, Utah, USA using models that support both delineation of wetland extent and projection of the changes in wetland area resulting from upstream hydrologic alteration. We linked stage-discharge relations developed by a hydraulic model to a flow-duration curve derived from the...

Populations of beaver and willow have not thrived in riparian environments that are heavily browsed by livestock or ungulates, such as elk. The interaction of beaver and elk herbivory may be an important mechanism underlying beaver and willow declines in this competitive environment. We conducted a field experiment that compared the standing crop of willow three years after simulated...

The National Wildlife Refuge System Improvement Act of 1997 requires all units of the National Wildlife Refuge System to be managed under a Comprehensive Conservation Plan (CCP). The CCP must describe the desired future conditions of a Refuge and provide long range guidance and management direction to achieve Refuge purposes. Arrowwood National Wildlife Refuge (NWR), located along the...

Elk browsing and conifer species mixing with aspen (Populus tremuloides Michx.) present current challenges to aspen forest management in the western United States. We evaluated the effects of conifers and elk browsing on quaking aspen stands in and near Rocky Mountain National Park using tree rings to reconstruct patterns of aspen establishment, growth, and mortality over the past 120...

The U.S. Fish and Wildlife Service (FWS) and the National Park Service (NPS) are preparing a management plan for bison and elk inhabiting the National Elk Refuge (NER) and Grand Teton National Park (GTNP). These animals are part of the bison and elk herds in Jackson Hole, one of the largest concentrations of free-ranging bison and elk in the world. A range of alternatives for managing...

The resilience of willow (Salix monticola Bebb, Salix geyeriana Anderss., Salix planifolia Pursh) stems released from intense elk (Cervus elaphus) browsing in Rocky Mountain National Park, Colorado, was quantified in 1998 with a retrospective study that compared biomass, number, and length of segments on willow stems located inside (protected) and outside (browsed) elk exclosures...

The Conservation Reserve Program (CRP) established under the 1985 Food Security Act has the fundamental objectives of jointly providing economic support to segments of the agricultural community and conservation of natural resources (Osborn, 1997; Heard and others, 2000). Although soil loss on highly erodable lands was the principal natural resource conservation issue addressed in the...

We anesthetized and blood sampled wild big brown bats (Eptesicus fuscus) in Fort Collins, Colorado (USA) in 2001 and 2002 and assessed effects on survival. Inhalant anesthesia was delivered into a specially designed restraint and inhalation capsule that minimized handling and bite exposures. Bats were immobilized an average of 9.1±5.1 (SD) min (range 1–71, n=876); blood sample volumes...