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Articles 31 - 60 of 80
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Fish Remains Dominate Barn Owl Pellets In Northwestern Nevada, Raymond J. Bogiatto, Jack M. Broughton, Virginia I. Cannon, Kevin Dalton, Shannon Arnold
Fish Remains Dominate Barn Owl Pellets In Northwestern Nevada, Raymond J. Bogiatto, Jack M. Broughton, Virginia I. Cannon, Kevin Dalton, Shannon Arnold
Western North American Naturalist
No abstract provided.
Rclus, A New Program For Clustering Associated Species: A Demonstration Using A Mojave Desert Plant Community Dataset, Stewart C. Sanderson, Jeffrey E. Ott, E. Durant Mcarthur, Kimball T. Harper
Rclus, A New Program For Clustering Associated Species: A Demonstration Using A Mojave Desert Plant Community Dataset, Stewart C. Sanderson, Jeffrey E. Ott, E. Durant Mcarthur, Kimball T. Harper
Western North American Naturalist
This paper presents a new clustering program named RCLUS that was developed for species (R-mode) analysis of plant community data. RCLUS identifies clusters of co-occurring species that meet a user-specified cutoff level of positive association with each other. The "strict affinity" clustering algorithm in RCLUS builds clusters of species whose pairwise associations all exceed the cutoff level, whereas the "coalition" clustering algorithm only requires that the mean pairwise association of the cluster exceeds the cutoff level. Both algorithms allow species to belong to multiple clusters, thus accommodating both generalist and specialist species. Using a 60-plot dataset of perennial plants occurring …
Naturalization Of Plains Cottonwood (Populus Deltoides Subsp. Monilifera) Along River Drainages West Of The Rocky Mountains, J. H. Braatne, S. J. Brunsfeld, V. D. Hipkins, B. L. Wilson
Naturalization Of Plains Cottonwood (Populus Deltoides Subsp. Monilifera) Along River Drainages West Of The Rocky Mountains, J. H. Braatne, S. J. Brunsfeld, V. D. Hipkins, B. L. Wilson
Western North American Naturalist
Historic botanical surveys documented that the natural distribution of the plains cottonwood (Populus deltoides subsp. monilifera) was limited to semiarid drainages east of the Rocky Mountains. Recently, a number of isolated populations of plains cottonwood have been found along the Kootenai, lower Snake, and Columbia Rivers and their tributaries. We used isozyme analysis to assess the genetic structure of these Pacific Northwest (PNW) populations in relation to native cottonwood populations east of the Rocky Mountains. These genetic data along with field surveys (dbh, age estimates) and cadastral field survey notes (mid-1800s) were used to understand the origin of …
Early Brood-Rearing Habitat Use And Productivity Of Greater Sage-Grouse In Wyoming, Kristin M. Thompson, Matthew J. Holloran, Steven J. Slater, Jarren L. Kuipers, Stanley H. Anderson
Early Brood-Rearing Habitat Use And Productivity Of Greater Sage-Grouse In Wyoming, Kristin M. Thompson, Matthew J. Holloran, Steven J. Slater, Jarren L. Kuipers, Stanley H. Anderson
Western North American Naturalist
Populations of Greater Sage-Grouse (Centrocercus urophasianus) have been declining throughout their range since the 1960s. Productivity, which includes production and survival of young, is often cited as a factor in these declines. We monitored radio-equipped Greater Sage-Grouse at 3 sites in western Wyoming to assess early brood-rearing habitat use (through 14 days post-hatch) and productivity. Logistic and linear regression analyses with Akaike's Information Criterion were used to evaluate early brooding habitat use and to examine relationships between productivity and vegetation, insect size and abundance, and weather parameters. Females with broods were found in areas with greater sagebrush canopy …
Influence Of Fire And Juniper Encroachment On Birds In High-Elevation Sagebrush Steppe, Anna C. Noson, Richard A. Schmitz, Richard F. Miller
Influence Of Fire And Juniper Encroachment On Birds In High-Elevation Sagebrush Steppe, Anna C. Noson, Richard A. Schmitz, Richard F. Miller
Western North American Naturalist
We examined relationships between high-elevation sagebrush (Artemisia spp.) steppe habitats altered by prescribed fire and western juniper (Juniperus occidentalis) encroachment on breeding distributions of Brewer's Sparrows (Spizella breweri), Vesper Sparrows (Pooecetes gramineus), Green-tailed Towhees (Pipilo chlorurus), and Sage Thrashers (Oreoscoptes montanus) on Steens Mountain in southeastern Oregon. In 2000 we conducted fixed-radius point count surveys at 172 sites encompassing burned and unburned sagebrush habitat and a range of juniper densities. For each bird species we developed habitat models using local variables measured in the field and landscape variables derived …
Production, Losses, And Germination Of Ceanothus Fendleri Seeds In An Arizona Ponderosa Pine Forest, David W. Huffman
Production, Losses, And Germination Of Ceanothus Fendleri Seeds In An Arizona Ponderosa Pine Forest, David W. Huffman
Western North American Naturalist
I quantified seed production and ovule losses for Ceanothus fendleri Gray (Fendler ceanothus) plants protected from large ungulate herbivores in a ponderosa pine (Pinus ponderosa [Laws]) forest of northern Arizona. I also tested seed germination responses to cold stratification and heat treatments in the laboratory. Fruit production on fecund stems ranged from 7.4 to 38.2 fruits per stem, which equated to 22.2–118.2 potential seeds based on 3 ovules per fruit. Stems that produced fruit were significantly large relative to their expected sizes. Predispersal ovule losses ranged from 70.7% to 91.4% across the 2 years studied. A chalcidoid seed parasite …
Observations Of Rapid Colonization Of Constructed Ponds By Western Toads (Bufo Boreas) In Oregon, Usa, Christopher A. Pearl, Jay Bowerman
Observations Of Rapid Colonization Of Constructed Ponds By Western Toads (Bufo Boreas) In Oregon, Usa, Christopher A. Pearl, Jay Bowerman
Western North American Naturalist
No abstract provided.
Ravens And Other Raptors Occupy Winter Roosts With Bald Eagles In Utah, Bryan T. Brown, Dana G. Truman, Linda Jones, Thomas Sharp
Ravens And Other Raptors Occupy Winter Roosts With Bald Eagles In Utah, Bryan T. Brown, Dana G. Truman, Linda Jones, Thomas Sharp
Western North American Naturalist
No abstract provided.
Great Salt Lake: An Anthology Edited By Gary Topping, C. Riley Nelson
Great Salt Lake: An Anthology Edited By Gary Topping, C. Riley Nelson
Western North American Naturalist
No abstract provided.
Observations On The Reproductive Biology Of Roundtail Chub, Gila Robusta, In The Upper Verde River, Arizona, Mark J. Brouder, Diana D. Rogers, Lorraine D. Avenetti
Observations On The Reproductive Biology Of Roundtail Chub, Gila Robusta, In The Upper Verde River, Arizona, Mark J. Brouder, Diana D. Rogers, Lorraine D. Avenetti
Western North American Naturalist
No abstract provided.
Comparison Of Gila Topminnow And Western Mosquitofish As Biological Control Agents Of Mosquitoes, Michael R. Childs
Comparison Of Gila Topminnow And Western Mosquitofish As Biological Control Agents Of Mosquitoes, Michael R. Childs
Western North American Naturalist
I compared acute tolerance of Gila topminnow, Poeciliopsis occidentalis, and western mosquitofish, Gambusia affinis, to ammonia and high water temperature and also compared diet, food selectivity, and impact on invertebrate populations to evaluate the potential for each species to effectively control mosquitoes (Culicidae) in wetland habitats. Critical thermal maxima differed among species, sexes, and lifestages, but these differences were likely not biologically significant due to their small magnitude and the ability of wild populations of both species to adapt to high temperatures. In 24-hour tests, G. affinis displayed about twice the ammonia tolerance as did P. occidentalis. …
Plant Species Richness At Different Scales In Native And Exotic Grasslands In Southeastern Arizona, Steven P. Mclaughlin, Janice E. Bowers
Plant Species Richness At Different Scales In Native And Exotic Grasslands In Southeastern Arizona, Steven P. Mclaughlin, Janice E. Bowers
Western North American Naturalist
Species richness in Madrean mixed-grass prairies dominated by native or exotic species in southeastern Arizona was characterized at the community and point scales using ten 1-m2 quadrats nested within each of eight 1000-m2 plots. In the 1000-m2 plots average richness was significantly higher in oak savanna (OS, 121.0 species) than in exotic grassland on mesa tops (EMT, 52.0 species), whereas native grassland on mesa slopes (NMS, 92.5 species) and native grassland on mesa tops (NMT, 77.0 species) did not differ significantly in richness from OS or EMT. When richness was partitioned by life form, EMT was notably …
Growth Rate And Thermal Tolerance Of Two Endangered Snake River Snails, Steven Lysne, Peter Koetsier
Growth Rate And Thermal Tolerance Of Two Endangered Snake River Snails, Steven Lysne, Peter Koetsier
Western North American Naturalist
We investigated the temperature tolerance and growth of 2 federally protected freshwater gastropods from southern Idaho: Valvata utahensis and Pyrgulopsis idahoensis. Snails were collected in the Snake River and transported to the laboratory where they were kept under highly controlled conditions. In varying-temperature, short-duration experiments, the temperatures tolerated by both species were between 7°C and 34°C. In constant-temperature, long-duration experiments, growth rates were between 0.004 mm · d−1 and 0.016 mm · d−1, and we created growth curves for both species that were previously lacking. Our results are among the first to report temperature tolerances and …
First Record Of Calochortus Apiculatus (Liliaceae) In Wyoming, Joseph R. Thomasson, Scott A. Thomasson, Daryl E. Mergen
First Record Of Calochortus Apiculatus (Liliaceae) In Wyoming, Joseph R. Thomasson, Scott A. Thomasson, Daryl E. Mergen
Western North American Naturalist
No abstract provided.
Current Records Of The Mexican Long-Tongued Bat, Choeronycteris Mexicana, In Baja California, Mexico, Ruben Couoh–De La Garza, Emma Flores-Rojas, Nazdry Briones-Escobedo, Eiracitlalli Hernández–Del Angel, Roberto Martínez-Gallardo, Juana Claudia Leyva Aguilera
Current Records Of The Mexican Long-Tongued Bat, Choeronycteris Mexicana, In Baja California, Mexico, Ruben Couoh–De La Garza, Emma Flores-Rojas, Nazdry Briones-Escobedo, Eiracitlalli Hernández–Del Angel, Roberto Martínez-Gallardo, Juana Claudia Leyva Aguilera
Western North American Naturalist
No abstract provided.
Hawks Rest: A Season In The Remote Heart Of Yellowstone By Gary Ferguson, Jordan C. Pederson
Hawks Rest: A Season In The Remote Heart Of Yellowstone By Gary Ferguson, Jordan C. Pederson
Western North American Naturalist
No abstract provided.
Age And Population Structure Of Joshua Trees (Yucca Brevifolia) In The Northwestern Mojave Desert, Kimberly D. Gilliland, Nancy J. Huntly, J. E. Anderson
Age And Population Structure Of Joshua Trees (Yucca Brevifolia) In The Northwestern Mojave Desert, Kimberly D. Gilliland, Nancy J. Huntly, J. E. Anderson
Western North American Naturalist
Many desert perennials are long-lived, but there are few data on ages or population structures of desert plants. We used 2 methods to estimate ages of a population of Yucca brevifolia (Joshua tree) in southwestern Utah from a 14-year census of plant sizes. Plant height at the 1st census ranged from 0.08 m to 6.0 m, and trees grew in height at a mean rate of 3.75 cm · yr−1. Plants also increased slowly in basal diameter (0.142 cm · yr−1) and branch length (0.024 m · yr−1), but basal diameter varied greatly from …
The Effect Of Livestock Grazing On The Rainbow Grasshopper: Population Differences And Ecological Correlates, Sandra J. Debano
The Effect Of Livestock Grazing On The Rainbow Grasshopper: Population Differences And Ecological Correlates, Sandra J. Debano
Western North American Naturalist
This study examined the effect of livestock grazing on a common herbivore in semiarid grasslands of the Southwest: the rainbow grasshopper, Dactylotum variegatum. Population attributes and key environmental variables were compared between sites on active cattle ranches and sites on a 3160-ha ungrazed sanctuary. Although density of D. variegatum nymphs did not differ significantly between grazed and ungrazed sites, adult density was significantly lower on grazed sites, and sex ratios differed between grazed and ungrazed sites over time. Grazed sites had higher percentages of bare ground and fewer Baccharis pteronioides, a common shrub. However, only bare ground was …
San Francisco's Golden Gate: A Bridge Between Historically Distinct Coyote (Canis Latrans) Populations?, Benjamin N. Sacks, Holly B. Ernest, Erin E. Boydston
San Francisco's Golden Gate: A Bridge Between Historically Distinct Coyote (Canis Latrans) Populations?, Benjamin N. Sacks, Holly B. Ernest, Erin E. Boydston
Western North American Naturalist
No abstract provided.
Yellowstone Country: The Photographs Of Jack Richard By Mark Bagne And Bob Richard, Don G. Despain
Yellowstone Country: The Photographs Of Jack Richard By Mark Bagne And Bob Richard, Don G. Despain
Western North American Naturalist
No abstract provided.
Factors Controlling Structural And Floristic Variation Of Riparian Zones In A Mountainous Landscape Of The Western United States, A. G. Merrill, T. L. Benning, J. A. Fites
Factors Controlling Structural And Floristic Variation Of Riparian Zones In A Mountainous Landscape Of The Western United States, A. G. Merrill, T. L. Benning, J. A. Fites
Western North American Naturalist
We examined landscape patterns in the physical conditions and vegetative composition of montane riparian zones to identify their most important sources of variation. Information on plant species cover and on physical characteristics that occur at coarse, medium, and fine scales was collected for 144 riparian plots located throughout the Lake Tahoe Basin, which straddles the California–Nevada border in the western United States. Constrained and unconstrained ordination analyses were used to identify the most important correlates of physical form and plant species composition. Through multivariate analysis of environmental variables (principal components analysis), vegetation data (detrended correspondence analysis), and the combined relationship …
New Records Of The Eastern Pipistrelle (Pipistrellus Subflavus) In Colorado, David M. Armstrong, Rick A. Adams, Karen E. Taylor
New Records Of The Eastern Pipistrelle (Pipistrellus Subflavus) In Colorado, David M. Armstrong, Rick A. Adams, Karen E. Taylor
Western North American Naturalist
No abstract provided.
Relation Of Fish Communities To Environmental Conditions In Urban Streams Of The Wasatch Front, Utah, Elise M. Giddings, Larry R. Brown, Terry M. Short, Michael R. Meador
Relation Of Fish Communities To Environmental Conditions In Urban Streams Of The Wasatch Front, Utah, Elise M. Giddings, Larry R. Brown, Terry M. Short, Michael R. Meador
Western North American Naturalist
Twenty-eight sites along the Wasatch Front, north central Utah, representing the range of 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 …
Gray Fox And Coyote Abundance And Diet Responses After A Wildfire In Central Arizona, Stan C. Cunningham, Laribeth Kirkendall, Warren Ballard
Gray Fox And Coyote Abundance And Diet Responses After A Wildfire In Central Arizona, Stan C. Cunningham, Laribeth Kirkendall, Warren Ballard
Western North American Naturalist
There is a paucity of information on the effects of wildfire on carnivores. We studied the effects of a 237-km2 catastrophic wildfire in the Mazatzal Mountains, Arizona, on gray foxes (Urocyon cinereoargenteus) and coyotes (Canis latrans). We indexed relative abundance 3 times each year from 1996 to 1998 using scat transects in burned and unburned areas. We collected scats to estimate diet and measured small mammal abundance and mast availability in 1997 and 1998. We also measured vegetation cover in burned and unburned sites. Gray fox indices declined 3 months postfire, but after 30 months, …
Tamarix Aphylla: A Newly Invasive Tree In Southern Nevada, Lawrence R. Walker, Pamela L. Barnes, Elizabeth A. Powell
Tamarix Aphylla: A Newly Invasive Tree In Southern Nevada, Lawrence R. Walker, Pamela L. Barnes, Elizabeth A. Powell
Western North American Naturalist
In the southwestern United States, the nonnative athel pine (Tamarix aphylla) was presumed to be sterile and therefore not as likely to spread as its widely distributed, nonnative congener, T. ramosissima. However, at Lake Mead National Recreation Area (LMNRA) in southern Nevada, populations of T. aphylla have recently spread beyond their limited pre-1990 distribution and now form extensive monospecific stands. Over a 3-year period, we quantified seed production and germination from 60 T. aphylla trees at LMNRA. The annual mean seed production period was 50.6 days, and the mean potential germination (under laboratory conditions) was 22%, indicating …
Characteristics Of Swift Fox Dens In Northwest Texas, Brady K. Mcgee, Kerry L. Nicholson, Warren B. Ballard, Matthew J. Butler
Characteristics Of Swift Fox Dens In Northwest Texas, Brady K. Mcgee, Kerry L. Nicholson, Warren B. Ballard, Matthew J. Butler
Western North American Naturalist
The swift fox (Vulpes velox) was classified in 1995 as a candidate for listing under the Endangered Species Act. Since then, several studies have addressed survey methods for monitoring swift fox populations. The purpose of this paper is to assist field researchers in documenting the presence of swift foxes by identification of recently active den sites. We propose that swift foxes have unique external den characteristics that can be distinguished during aerial surveys. We collected data from 30 swift fox den complexes on both continuous rangeland and landscapes fragmented by cropland in northwest Texas. There were no differences …