Publications

Conceptual1,2,3,4 and numerical5,6,7,8 models of nitrogen cycling in temperate forests assume that nitrogen is lost from these ecosystems predominantly by way of inorganic forms, such as nitrate and ammonium ions. Of these, nitrate is thought to be particularly mobile, being responsible for nitrogen loss to deep soil and stream waters. But human activities—such as fossil fuel combustion

Sagebrush lands in the Intermountain West are declining rapidly in quality and extent. Consequently, populations of many bird species dependent on these ecosystems also are declining. The greater sage-grouse has been petitioned for listing as a threatened and endangered species, and other species of sagebrush-obligate birds have special conservation status in most states. We identified...

From early April through September each year, famous residents grace the small western town of Corvallis, Oregon. Two ospreys have become mascots of the town since the pair's arrival in 1994. Their nest, built on a 90-foot power pole near the twin bridges over the Willamette River, could be seen by many commuters on their way in and out of town. After the 2002 nesting season, the nest...

Fire is a natural feature of sagebrush grasslands in the Great Basin. The invasion of exotic annual grasses, such as Bromus tectorum (cheatgrass), has changed the environment in these ecosystems. Invasive annual grasses provide a dense and continuous source of fuel that extends the season for fires and increases the frequency of fires in the region. Frequent fires eventually eliminate...

We are integrating field surveys with information obtained from satellite imagery to determine how birds respond to the habitat changes in shrubland regions in the Intermountain West. Our objectives are to determine the primary causes that change shrubland habitats, the spatial and temporal scales at which shrubland landscapes change, and the mechanisms by which distribution and...

A National Association of Geoscience Teachers Far Western Section (NAGT-FWS) field conference is an ideal forum for learning about the geology and natural history of the San Francisco Bay area. We visit classic field sites, renew old friendships, and make new ones. This collection of papers includes field guides and road logs for all of the Bay-area trips held during the NAGT-FWS 2001...

Effects of color bands on adult birds have been investigated in many studies, but much less is known about the effects of bands on birds banded at hatch. We captured Semipalmated Sandpiper (Calidris pusilla) chicks at hatch on the Alaskan North Slope and attached 0–3 bands to them. The chicks were resighted and reweighed during the subsequent two weeks. The number of chicks banded varied...

Sturgeon are an important fishery resource world-wide, providing food and income through commercial, sport, and tribal fisheries. However, sturgeon populations are imperiled in many areas due to overharvest, habitat loss, and pollution. White Sturgeon (Acipenser transmontanus) are found along the west coast of North America from San Francisco Bay, USA to British Columbia, Canada. The...

Estimates are presented for the population sizes of 53 species of Nearctic shorebirds occurring regularly in North America, plus four species that breed occasionally. Population estimates range from a few tens to several millions. Overall, population estimates most commonly fall in the range of hundreds of thousands, particularly the low hundreds of thousands; estimated population sizes...

Improved understanding of tree growth responses to climate is needed to model and predict forest ecosystem responses to current and future climatic variability. We used dendroecological methods to study the effects of climatic variability on radial growth of a subalpine conifer, mountain hemlock (Tsuga mertensiana). Tree-ring chronologies were developed for 31 sites, spanning the...

We compared habitat use, forage characteristics, and group size among preparturient, parturient, and nonparturient female caribou (Rangifer tarandus) during and after the birthing season to test hypotheses involving acquisition of forage and risk of predation. We monitored 39 radiocollared females from the Mentasta caribou herd, Alaska, in 1994 and 40 animals in 1995. Group size of...

Humans have affected grizzly bears (Ursus arctos horribilis) by direct mortality, competition for space and resources, and introduction of exotic species. Exotic organisms that have affected grizzly bears in the Greater Yellowstone Area include common dandelion (Taraxacum officinale), nonnative clovers (Trifolium spp.), domesticated livestock, bovine brucellosis (Brucella abortus), lake...