Publications

Twenty-two high-elevation lakes (>3000 m) in Rocky Mountain National Park and Indian Peaks Wilderness Area, Colorado, were surveyed during summer 1998 to explore relationships among benthic invertebrates, water chemistry (particularly nitrate concentrations), and other environmental variables. Water samples were collected from the deepest portion of each lake and analyzed for ions and...

Several National Park Service units in the Intermountain region possess a number of closely related management needs relative to the abundance of wild ungulates and their herbivory effects on plants and ecosystem processes. In 1993, the then National Biological Service (NBS) - now U.S. Geological Survey, Biological Resources Discipline (USGS, BRD)­ initiated a series of research studies...

In 1998, the USGS Global Change program funded research for a network of Long-Term Reference Ecosystems initially established in national parks and funded by the National Park Service. The network included Noland Divide, Great Smoky Mountains National Park, Tennessee; Pine Canyon, Big Ben National park, Texas; West Twin Creek, Olympic National Park, Washingtona?? Wallace Lake, Isle...

Energetic costs of nest construction are difficult to estimate for birds, and currently estimates are available for only a handful of species. In this paper, I estimate the minimum cost of nest construction by a pair of Black-billed Magpies (Pica hudsonia). Data on the number of sticks and mud pellets comprising a nest were used to determine the minimum number of trips required to...

Most studies of the potential ecological and economic impacts of climate change and greenhouse warming have focused on scenarios that involve gradual climate change. Accumulating evidence from the paleosciences, however, shows that the patterns of change suggested by projections of future climate change are not representative of past climatic changes or of the transitions between...

No abstract available.

No abstract available.

We evaluated nesting habitat selection (disproportionate use compared to availability) by plains sharp-tailed grouse (Tympanuchus phasianellus jamesi) on rangelands grazed by cattle (Bos taurus) relative to height, density, and heterogeneity of residual herbaceous vegetation remaining from previous growing seasons. Residual cover is critical for nesting sharp-tailed grouse and can be...

SALMOD is a computer model that simulates the dynamics of freshwater salmonid populations, both anadromous and resident. The conceptual model was developed in a workshop setting (Williamson et al. 1993) using fish experts concerned with Trinity River chinook restoration. The model builds on the foundation laid by similar models (see Cheslak and Jacobson 1990). The model’s premise that...

The systematic relationship between Myotis lucifugus carissima and Myotis occultus has been the subject of multiple studies. Although several studies, including a recent allozyme study, concluded that M. occultus is a subspecies of M. lucifugus, this view has not been universally accepted. We reexamined the relationships of these 2 taxa by sequencing the mitochondrial cytochrome-b (cyt-b...

A new species of the genus Echinosaura is described from the Pacific drainages of northern Ecuador and adjacent Colombia. Evaluation of variation among congeners justifies their recognition as distinct species instead of subspecies as previously proposed. The new lizard occurs in close proximity to Echinosaura horrida and Teuchocercus keyi.

No abstract available.