Skip to main content
USGS - science for a changing world
Advanced Search

Filters: Tags: Western North American Naturalist (X)

198 results (102ms)   

View Results as: JSON ATOM CSV
thumbnail
Interspecies interactions can affect how species are distributed, put constraints on habitat expansion, and reduce the fundamental niche of the affected species. Using logistic regression, we analyzed and compared 174 Tamias palmeri and 94 Tamias panamintinus within an isolated mountain range of the Basin and Range Province of southern Nevada. Tamias panamintinus was more likely to use pinyon/ponderosa/fir mixed forests than pinyon alone, compared to random sites. In the presence of T palmeri, however, interaction analyses indicated T. panamintinus was less likely to occupy the mixed forests and more likely near large rocks on southern aspects. This specie s-by-habitat interaction data suggest that T. palmeri excludes...
thumbnail
First paragraph of introduction: On 20 July 2004 a single Asian tapeworm (Bothriocephalus acheilognathi) was collected from the intestine of a roundtail chub (Gila robusta) in the Yampa River in Dinosaur National Monument in northwestern Colorado. This fish (274 mm TL) was collected at river mile 24 and dissected in the field. A single tapeworm was removed from the intestine and preserved in ethanol. The tapeworm was later identified in the laboratory as B. acheilognathi by its characteristic arrow-shaped scolex (Poole et al. 1984). This is the 1st recorded incidence of Asian tapeworm infecting fish in the Yampa River drainage. Published in Western North American Naturalist, volume 65, issue 3, on pages 403 - 404,...
thumbnail
Sage-grouse (Centrocercus spp.) were abundant in all of Utah's 29 counties at the time of European settlement wherever sagebrush (Artemisia spp.) occurred. Greater Sage-Grouse (G. urophasianus) inhabited areas north and west of the Colorado River, and Gunnison Sage-Grouse (G. minimus) occupied suitable habitat south and east of the Colorado River. The largest Greater Sage-Grouse populations in Utah are currently restricted to suitable habitats in Box Elder, Garfield, Rich, Uintah, and Wayne Counties. A remnant breeding population of Gunnison Sage-Grouse occurs in eastern San Juan County. We stratified Greater Sage-Grouse populations (1971-2000) by counties where the 1996 to 2000 moving average for estimated spring...
thumbnail
Resource specialists at Dinosaur National Monument utilize both planned and unplanned wildland ignitions in big sagebrush (Artemisia tridentata)--dominated plant communities to restore successional processes, maintain vegetation vigor, and promote diversified landscapes. Short- and long-term effects of prescribed burning on small mammal populations are not well understood. The objectives of this study were to (1) compare small mammal species richness, similarity, and diversity between paired burned and unburned treatment plots, and (2) assess long-term trends of small mammal community responses to burning. Five paired burned/unburned sites having similar vegetation, soils, elevation, and annual precipitation were...
thumbnail
Disturbance in riparian areas of semiarid ecosystems involves complex interactions of pulsed hydrologic flows, herbivory, fire, climatic effects, and anthropogenic influences. We resampled riparian vegetation within ten 10-m × 100-m plots that were initially sampled in 1992 in 4 watersheds of the Snake Range, east central Nevada. Our finding of significantly lower coverage of grasses, forbs, and shrubs within plots in 2001 compared with 1992 was not consistent with the management decision to remove livestock grazing from the watersheds in 1999. Change over time in cover of life-forms or bare ground was not predicted by scat counts within plots in 2001. Cover results were also not well explained by variability between...
thumbnail
Forests of the southern Rocky Mountains are punctuated by persistent meadows called parks that are dominated by grasses and forbs. In an attempt to elucidate the maintenance of subalpine parks in the Gunnison Basin, Colorado, soil texture and tree morphology differences along 60-m transects spanning the forest-park ecotone were studied in 6 representative parks. Seedling survivorship, percent seed germination, and soil moisture available to plants were also studied along one of the transects in Willow Park. Soil analyses revealed 40% more silt and significantly less sand and clay in all 6 parks (P < 0.001), which supports the traditional hypotheses that edaphic factors are involved in restricting establishment of...
Plant macrofossils from packrat middens in two southeastern Utah caves outline development of modern plant zonation from the late Wisconsin. Allen Canyon Cave (2195 m) and Fishmouth Cave (1585 m) are located along a continuous gradient of outcropping Navajo Sandstone that extends from the Abajo Mountains south to the San Juan River. By holding the site constant, changes in the floral composition for a plot of less than one hectare can be observed, even if sporadically, over tens of millennia. At Allen Canyon Cave, Engelmann spruce-alpine fir forest was replaced by the present vegetation consisting of pinyon-juniper woodland on exposed ridgetops and cliffside stands of Douglas fir, ponderosa pine, and aspen. Xerophytic...
Five alcoves (rock shelters) in the Forty-Mile Canyon—Willow Gulch area of the Escalante River Basin in southeastern Utah yielded rich deposits of late Quaternary macrobotanical remains. The deposits were sampled and the contents identified in order to construct a chronology of vegetational change. Fourteen radiocarbon dates indicate that the fossils were deposited between 12,690 and 7510 yr B.P. (years before present). Ninety-one plant taxa were identified, 62 to species. Six species were common to all alcoves: Gambel oak (Quercus gambelii), box-elder (Acer negundo), prickly pear (Opuntia subgenus Platyopuntia), skunkbush (Rhus aromatica var. trilobata), serviceberry (Amelanchier utahensis), and Indian ricegrass...
thumbnail
The Mountain Plover (Charadrius montanus) is a shorebird species endemic to the dry, terrestrial ecosystems of the Great Plains and southwestern United States. Breeding Bird Survey data suggest that Mountain Plover populations have declined by >60% in the last 30 years. A better understanding of the population dynamics of the Mountain Plover is important in determining future management goals for this species. However, this effort is hampered by the inability to determine the sex of Mountain Plovers accurately under field conditions. In an effort to develop a simple method for sexing plovers in the hand, we measured external morphometric characteristics from 190 museum specimens of adult Mountain Plovers in alternate...
thumbnail
Big Spring spinedace (Lepidomeda mollispinis pratensis) is a cyprinid whose entire population occurs within a section of Meadow Valley Wash, Nevada. Other spinedace species have suffered population and range declines (one species is extinct). Managers, concerned about the vulnerability of Big Spring spinedace, have considered habitat restoration actions or translocation, but they have lacked data on distribution or habitat use. Our study occurred in an 8.2-km section of Meadow Valley Wash, including about 7.2 km in Condor Canyon and 0.8 km upstream of the canyon. Big Spring spinedace were present upstream of the currently listed critical habitat, including in the tributary Kill Wash. We found no Big Spring spinedace...
Discovery of distinct mid-elevational bands of blackbrush (Coleogyne ramosissima Torr.) shrublands on desert mountain slopes in the Mojave Desert caused an investigation of the relationships between environmental factors and Coleogyne distribution. Environmental factors were quantitatively examined to determine which were significant predictors of Coleogyne density at upper-elevational limits (ecotones) in the Spring Mountains of southern Nevada. Path analysis revealed significant, direct causal effects of air temperature, soil moisture, soil depth, and percent litter cover on the distribution of Coleogyne. Specifically, air temperature was a significant positive predictor, while soil moisture, soil depth, and percent...
thumbnail
Despite their trophic importance and potential importance as bioindicators of stream condition, benthic algae have not been well studied in California. In particular there are few studies from small streams in the Sierra Nevada. The objective of this study was to determine the standing crop of chlorophyll-a and benthic algal species assemblages present in the small 1st- and 2nd-order streams of the Kings River Experimental Watersheds (KREW, watersheds of Bull, Providence, Duff, and Teakettle Creeks) and determine the associations of these measures with stream habitat. We collected samples of benthic algae from rock substrata in September 2002 (7 sites) and 2005 (the same 7 sites plus 5 additional sites). Habitat...
thumbnail
We compared vegetation structure used by 14 bird species during the 1998 and 1999 breeding seasons to determine what habitat features best accounted for habitat division and community organization in Utah juniper (Juniperus osteosperma) woodlands of southwestern Wyoming. Habitat use was quantified by measuring 24 habitat variables in 461 bird-centered quadrats, each 0.04 ha in size. Using discriminant function analysis, we differentiated between habitat used by 14 bird species along 3 habitat dimensions: (1) variation in shrub cover, overstory juniper cover, mature tree density, understory height, and decadent tree density; (2) a gradient composed of elevation and forb cover; and (3) variation in grass cover, tree...
thumbnail
Caching of animal remains is common among carnivorous species of all sizes, yet the effects of caching on larger prey are unstudied. We conducted a summer field experiment designed to test the effects of simulated mountain lion (Puma concolor) caching on mass loss, relative temperature, and odor dissemination of 9 prey-like carcasses. We deployed all but one of the carcasses in pairs, with one of each pair exposed and the other shaded and shallowly buried (cached). Caching substantially reduced wastage during dry and hot (drought) but not wet and cool (monsoon) periods, and it also reduced temperature and discernable odor to some degree during both seasons. These results are consistent with the hypotheses that caching...
thumbnail
Twenty-eight sites along the Wasatch Front, north central Utah, representing the range ot urban land use intensity for wadeable streams of the area, were sampled in September 2000. Fish communities were assessed by single-pass electrofishing, and physical habitat and water-quality characteristics were measured. On average, nonnative species comprised 54% of species richness and 53% of relative abundance, although only Salmo trutta and Pimephales promelas were very abundant at any 1 site. Salmo trutta and Catostomus platyrhynchus, a native species, were the most widely distributed and abundant species captured. Analysis of fish communities using nonmetric multidimensional scaling (NMDS) revealed a community gradient...
thumbnail
We evaluated the thermal regime and relative abundance of native and nonnative fish and invertebrates within Kelly Warm Spring and Savage Ditch, Grand Teton National Park, Wyoming. Water temperatures within the system remained relatively warm year-round with mean temperatures >20 °C near the spring source and >5 °C approximately 2 km downstream of the source. A total of 7 nonnative species were collected: Convict/Zebra Cichlid (Cichlasoma nigrofasciatum), Green Swordtail (Xiphophorus hellerii), Tadpole Madtom (Noturus gyrinus), Guppy (Poecilia reticulata), Goldfish (Carassius auratus), red-rimmed melania snail (Melanoides tuberculata), and American bullfrog tadpoles (Lithobates catesbeianus). Nonnative fish (Zebra...
thumbnail
Wind turbines are being deployed all across the world to meet the growing demand for energy, and in many areas, these turbines are causing the deaths of insectivorous migratory bats. One of the hypothesized causes of bat susceptibility is that bats are attracted to insects on or near the turbines. We examined insect remains in the stomachs and intestines of hoary bats (Lasiurus cinereus) found dead beneath wind turbines in New York and Texas to evaluate the hypothesis that bats die while feeding at turbines. Most of the bats we examined had full stomachs, indicating that they fed in the minutes to hours leading up to their deaths. However, we did not find prey in the mouths or throats of any bats that would indicate...
thumbnail
In northwestern Colorado, flow regulation on the Green River has created a transitional plant community that features encroachment by upland vegetation into cottonwood (Populus fremontii)-dominated, riparian forest on topographically high floodplain sites and reduced cottonwood regeneration on low floodplain sites. To assess how these changes might have affected small mammal distributions, in 1994 and 1995 we live-trapped during periods surrounding spring flooding at 3 sites: above and below the confluence of the regulated Green River and at the ecologically similar, but unregulated, Yampa River (reference site). More species were captured at the most regulated site along the Green River above its confluence with...
Artemisia carruthii and A. frigida of the subgenus Artemisia and A. filifolia and A. spinescens of the subgenus Dracunculus all have chromosome numbers based on x = 9. Diploid (2n = 18) karyotypes of each species are composed of large, medium, and small chromosomes that are mainly metacentric and submetacentric. The individual karyotypes are similar but distinctive. Artemisia filifolia?s karyotype and chemistry is quite similar to that of Section Tridentatae, but A. filifolia has significant morphological differences with respect to the Tridentatae. Artemisia spinescens includes a tetraploid (2n = 36) population as well as diploid populations. Karyotypic analysis of a tetraploid A. spinescens suggests that it is...


map background search result map search result map Changes in the distribution and status of sage-grouse in Utah Fire effects on small mammal communities in Dinosaur National Monument Persistence of subalpine forest--meadow ecotones in the Gunnison Basin, Colorado Collection of Asian tapeworm ( Bothriocephalus acheilognathi ) from the Yampa River, Colorado Distribution and movement of Big Spring spinedace (<i>Lepidomeda mollispinis pratensis</i>) in Condor Canyon, Meadow Valley Wash, Nevada Habitat interaction between two species of chipmunk in the Basin and Range Province of Nevada Distribution and movement of Big Spring spinedace (<i>Lepidomeda mollispinis pratensis</i>) in Condor Canyon, Meadow Valley Wash, Nevada Fire effects on small mammal communities in Dinosaur National Monument Collection of Asian tapeworm ( Bothriocephalus acheilognathi ) from the Yampa River, Colorado Habitat interaction between two species of chipmunk in the Basin and Range Province of Nevada Persistence of subalpine forest--meadow ecotones in the Gunnison Basin, Colorado Changes in the distribution and status of sage-grouse in Utah