Skip to main content
Advanced Search

Filters: Tags: Western North American Naturalist (X)

80 results (111ms)   

View Results as: JSON ATOM CSV
thumbnail
Symphyotrichum expansum (Puepp ex Spreng.) Nesom is reported new to Utah from the Escalante River drainage. A major range extension is reported for Aralia racemosa L. in the Escalante drainage, and additional populations are reported of the rare species Imperata brevifolia Vasey in Utah, including the 1st record for the Grand Staircase--Escalante National Monument. Heterotheca grandiflora Nutt. is reported new to north central Arizona. New locations and notes on an additional 22 rare species in Glen Canyon National Recreation Area are listed. Published in Western North American Naturalist, volume 65, issue 1, on pages 103 - 111, in 2005.
Erigeron kachinensis is a rare endemic of the Colorado Plateau in southeastern Utah. This perennial composite grows in small, isolated populations at seeps and alcoves arising along canyon walls in Cedar Mesa Sandstone substrates. Characteristics of six Erigeron kachinensis sites in Natural Bridges National Monument, San Juan County, Utah, were studied to determine habitat requirements for this species. Sites were analyzed with respect to geology, soil chemistry, physical properties, and vegetational characteristics. The alcoves studied were very saline, often with soil surfaces covered with a white crust of salt. Living cover was enhanced by perennially moist soils, diminished amounts of solar radiation, soil salinity,...
We determined temporal and spatial differences in abundance and habitat use by small mammals in southeastern Utah as part of an effort to enhance management of the Mexican Spotted Owl (Strix occidentalis lucida), listed by the federal government as threatened. Woodrats (Neotoma spp.) were captured only in canyons and most frequently in the pinyon-juniper (Pinus edulis-Juniperus osteosperma) vegetation type. White-footed mice (Peromyscus spp.) were found in a variety of vegetation types in both canyons and mesas. The deer mouse (P. maniculatus) was generally the most frequently captured species among vegetation types. We found seasonal and yearly differences in relative abundance of each small mammal species. Our...
Several species of raptors winter at Rocky Mountain Arsenal National Wildlife Refuge (Refuge) including the Bald Eagle (Haliaeetus leucocephalus), Ferruginous Hawk (Buteo regalis), Red-tailed Hawk (Buteo jamaicensis), and Rough-legged Hawk (Buteo lagopus). Raptors were monitored each winter from 1988-89 to 1996-97 using a standardized road survey. Black-tailed prairie dogs (Cynomys ludovicianus) form a major component of the prey base for wintering raptors on the Refuge, with 1850 ha of active prairie dog towns mapped in 1988. Prairie dog town areas and population data were determined by mapping active towns and conducting visual counts on study plots to determine population density on an annual basis from 1988...
The charaeteristics of kokanee (Oncorhynchus nerka) spawning stocks in the Green River and Sheep Creek (tributaries to Flaming Gorge Reservoir) are described as observed in fall 1985 and spring 1986; the time of spawning; length, age, and sex structure of the stocks; fecundity and egg retention; density of eggs in redds; and the timing of downstream drift of emerging fry. The time of spawning, length-frequency distributions of spawning fish, and egg density in redds differed between the two stocks, but other differences were not observed. Published in Western North American Naturalist, volume 48, issue 1, on pages 46 - 50, in 1988.
Northern pike, Esox lucius, stocked in the Yampa River in 1977, invaded the mainstream Green River by 1981 and subsequently increased in range and abundance. The speed of this invasion is indicated by two recaptured pike that moved 78 and 110 km, respectively, downstream in about one year. Pike stomachs (n = 123) were usually empty (54.5%), but some contained fish (43%) and nonfish items (2.4%). Red shiner, Notropis lutrensis, and fathead minnow, Pimephales promelas, predominated among the 12 fish species eaten. Walleye, Stizostedion vitreum, presumably introduced to the Green River drainage in the 1960s, was widely distributed but low in abundance. Most of 61 adult walleye stomachs contained food (60.7%) ; of 6...
Mountain big sagebrush (Artemisia tridentata Nutt. ssp. vaseyana) covers large areas in arid regions of western North America. Climate-change models predict a decrease in the range of sagebrush, but few studies have examined details of predicted changes on sagebrush growth and the potential impacts of these changes on the community. We analyzed effects of temperature, precipitation, and snow depth on sagebrush annual ring width for 1969 to 2007 in the Gunnison Basin of Colorado. Temperature at all times of year except winter had negative correlations with ring widths; summer temperature had the strongest negative relationship. Ring widths correlated positively with precipitation in various seasons except summer;...
In both field and greenhouse studies, cyanobacterial and cyanolichens of cold-temperature deserts often enhance growth and essential uptake by associated herbs. That effect is associated with better seedling establishment and larger seedlings. The following are possible mechanisms for these effects: (1) the microbiota concentrate essential elements in available forms in soil surface layers, (2) the microbial surface covers are usually darker colored than the soil itself and produce warmer soils during cool seasons when soil water is most available, (3) the gelatinous sheaths of several cyanobacterial genera common on alkaline deserts contain chelating compounds, and (4) conditions that favor persistent microbial...
Only a single previous study has examined ectoparasites of the occult bat (Myotis occultus), from which only 2 species of fleas were identified. For our study, we examined 202 individuals, 52 fresh hosts and 150 museum specimens, from New Mexico and southern Colorado for ectoparasites. We recorded 2158 ectoparasites, 634 from fresh hosts and 1524 from museum specimens. Ectoparasites belonged to 10 families and 13 genera of insect or acari and represent new host and locality records. In general, ectoparasites collected from fresh hosts and museum specimens were represented by 4 major species of mite: Macronyssus crosbyi, Alabidocarpus calcaratus, Acanthophthirius lucifugus, and Alabidocarpus nr. eptesicus. From our...
Seventeen subadult, hatchery-reared razorback suckers (Xyrauchen texanus; (x? = 456 mm total length) were implanted with sonic transmitters and tracked for 23 months in the lower 89.6 km of the San Juan River (San Juan arm of Lake Powell, Utah). Fish were released at 2 sites, and 9 made extensive up- and downstream movements (x? = 47.8 km; contact was lost with 4, and 4 others presumably died or lost their transmitters). The San Juan arm is primarily inundated canyon; however, most fish contacts occurred in shallow coves and shoreline with thick stands of flooded salt cedar in the upper inflow area. Eight fish frequented the Piute Farms river/lake mixing zone, and at least 4 moved upstream into the San Juan River....
Juvenile razorback sucker (Xyrauchen texanus) in a managed wetland adjacent to the Green River, credited to Modde, Timothy, published in 1996. Published in Western North American Naturalist, volume 56, issue 4, on pages 375 - 376, in 1996.
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...
Used first paragraph of article as the abstract: We collected an adult gizzard shad (Doro- soma cepedianum) from the San Juan River just upstream of Lake Powell, Utah, on 6 June 2000. This represents the first documented occurrence of the species in the Colorado River or its tributaries. The adult male (35 cm TL, 470 g) was taken by trammel net from a small (0.5 ha), shallow (<2 m) backwater along with several other fish that included 3 endan- gered razorback sucker (Xyrauchen texanus). The specimen is stored at the Museum of Southwestern Biology, University of New Mexico, Albuquerque (curation number 49122). Published in Western North American Naturalist, volume 64, issue 1, on pages 135 - 136, in 2004.
Naturalized populations of nonnative salmonid fishes have been implicated in the decline of many native aquatic organisms, including amphibians (Bradford 1989), invertebrates (Polhemus 1993), and fishes (Moyle et al. 1986). Potential mechanisms by which nonnative fishes may interact with native biota include predation, competition, parasite and disease transmission, and hybridization, which may operate directly or indirectly (see Taylor et al. 1984 for a general review). Nonnative salmonids are frequently implicated in declines of native salmonids in the western United States (Allendorf and Leary 1988, Young 1995, Duff 1996). For example, loss of threatened Lahontan cutthroat trout (Oncorhynchus clarki henshawi)...
The effect of flow regulation on plant-herbivore ecology has received very little attention, despite the fact that flow regulation can alter both plant and animal abundance and environmental factors that mediate interactions between them. To determine how regulated flows have impacted beaver (Castor Canadensis) and sandbar willow (Salix exigua) ecology, we first quantified the abundance and mapped the spatial distribution of sandbar willow on alluvial sections of the flow-regulated Green River and free-flowing Yampa River in northwestern Colorado. We then established 16 and 15 plots (1 m x 2.7 m) in patches of willow on the Green and Yampa Rivers, respectively, to determine whether rates of beaver herbivory of willow...
thumbnail
Examination of gastrointestinal tracts of native cyprinids from the Little Colorado River (LCR) in Grand Canyon, Arizona, 1990-1994, revealed varying rates of prevalence and infrapopulation levels of Asian tapeworm (Bothriocephalus acheilognathi). Mean prevalence was 28% (range 0-78%) in humpback chub (Gila cypha) and 8% (range 0-46%) in speckled dace (Rhinichthys osculus), with infrapopulations as high as 46 and 28, respectively. We also note Asian tapeworm infection of nonnatives common carp (Cyprinus carpio), fathead minnow (Pimephales promelas), and plains killifish (Fundulus zebrinus) from the LCR. Reported pathogenic and chronic effects of this cestode to its definitive hosts add concern for the status of...
Thirty-four study sites were established in shadscale (Atriplex confertifolia [Torr. & Frem.] Wats.) and greasewood (Sarcobatus vermiculatus [Hoov. Torr. in Emory) communities bordering Utah Lake in central Utah. Differences in species composition, vegetation, and soil characteristics were assessed. Significant differences in soil factors between the two communities were found for sand, calcium, manganese, zinc, and copper. Soluble salts and sodium concentrations were generally higher in the greasewood type, but differences were not significant. Major differences were found in understory species, with burr buttercup (Ranunculus testiculatus Grantz) showing significantly greater cover in the shadscale community and...
Growth of smallmouth bass (Micropterus dolomieu) was described for three widely spaced areas progressing downstream in Flaming Gorge Reservoir, Wyoming-Utah. Significant differences among areas were detected only for age-1 fish. Growth in the reservoir was compared with that of populations in other lentic habitats of varying growing season lengths in North America; slow growth in the reservoir was related to the relatively short growing season (less than 90 days). Published in Western North American Naturalist, volume 53, issue 2, on pages 180 - 185, in 1993.
Three desert Artemisia tridentata communities in Rush Valley, Utah, were trapped for small rodents during the summer of 1970, and population densities were estimated for each population category using Lincoln's index. Animals were weighed and rodent biomass calculated by species throughout the summer. Population, biomass, and other data were then analyzed to gain an understanding of the community relationships of the three study areas to each other as well as to the A. tridentata community types of the Great Basin. Peromyscus maniculatus, Eutamias minimus, and Reithrodontomys megalotis were common to area 1, whereas P. maniculatus, E. minimus, and Perognathus parvus were common to areas 2 and 3. The peak estimated...
We analyzed the microtopography of microbiotic soil crusts at 3 sites on the Colorado Plateau of southern Utah and investigated distributions of cyanobacteria and several lichens in distinctive microhabitats created by this topography. At all 3 sites the long axes of linear soil mounds were oriented nonrandomly in a NNW?SSE direction. The conspicuous and consistent orientation of soil mounds may result from a combination of physical and biotic processes. Subtle differences across sites in mound orientation and organismal distribution suggest that these variables may be useful in comparing disturbance histories of crusts retrospectively. Differences in colonization frequencies, abundances, and distributions of microorganisms...
map background search result map search result map Asian tapeworm (Bothriocephalus acheilognathi) in native fishes from the Little Colorado River, Grand Canyon, Arizona Notes on significant collections and additions to the flora of Glen Canyon National Recreation Area, Utah and Arizona, between 1992 and 2004 Asian tapeworm (Bothriocephalus acheilognathi) in native fishes from the Little Colorado River, Grand Canyon, Arizona Notes on significant collections and additions to the flora of Glen Canyon National Recreation Area, Utah and Arizona, between 1992 and 2004