Range- and wildlands are being invaded by nonindigenous plants, resulting in an unprecedented, rapid change in plant community composition across the United States. Successional management predicts that species performance may be modified by resource availability. The objective of this study was to determine whether species performance could be altered by modifying soil nitrate (NO₃–) and ammonium (NH₄ ) concentrations within an Idaho fescue (Festuca idahoensis)/bluebunch wheatgrass (Pseudoroegneria spicata) plant association. We planted bluebunch wheat-grass and spotted knapweed (Centaurea maculosa) in an addition series at 2 sites in southwestern Montana. Each plot in the addition series matrix was divided into thirds, and we applied nitrogen (N) to a subplot and sucrose to a 2nd subplot. The remaining subplot was not amended and considered a control. Nitrogen amendment tended to enhance the performance of spotted knapweed, while sucrose amendment had no effect. Bluebunch wheatgrass performance was not affected by either amendment. Sucrose treatments only decreased soil NO₃– at the more productive site. Regression models for predicting bluebunch wheatgrass and spotted knapweed biomass accounted for only about 30% of the variation, suggesting other processes in addition to interference were responsible for explaining relative plant performance. We recommend that land managers prevent activities that increase soil N concentration while the effectiveness of carbon amendments as a means to decrease soil N concentrations and shift interference relationships is further investigated.

Shrubsteppe ecosystems in the Intermountain West have suffered extreme alteration from a variety of factors. Using a retrospective approach, I studied the effects of horse and cattle grazing at the northern edge of the range in southern British Columbia, Canada, where the shrubsteppe is not as heavily altered and ungrazed sites remain in areas dominated by antelope bitterbrush (Purshia tridentata). I measured shrub and understory cover at 10 sites that were either ungrazed, lightly grazed, or heavily grazed. Cover of antelope bitterbrush decreased with grazing, and cover of big sagebrush (Artemisia tridentata) increased with grazing intensity. I sampled 72 species of vascular plants in the understory. Livestock grazing resulted in more bare soil, especially at sandy rather than rocky sites, and in quadrats located in the interspaces between shrubs. More bare soil was associated with less spikemoss (Selaginella spp.) and less microbiotic crust cover. Of the 3 most common bunchgrasses, sand dropseed (Sporobolus cryptandrus) was associated with more bare soil but only at sites without spikemoss. Red three-awn (Aristida purpurea var. longiseta), which grew best without litter or microbiotic crust, was most commonly found with spikemoss. Needle-and-thread grass (Hesperostipa comata), the most palatable abundant bunchgrass, was affected by livestock grazing, with shrub canopy cover offering some protection from grazers at the most heavily grazed sites. Rangeland management prescriptions in this area should take soil differences into account, with sandy soils being more prone to overgrazing and disturbance of the microbiotic crust cover than rocky soils.

There are no published studies on the diet of Mogollon voles (Microtus mogollonensis) although this species occurs throughout the Southwest in montane forestlands. Mogollon voles are believed to be herbivorous, selecting the vegetative portion of grass as their dominant food source. Herbivores frequently select more easily digested C₃ plants over C₄ plants; we thus expected Mogollon voles would feed primarily on C₃ plants. We collected hair samples from Mogollon voles captured in northern Arizona between 1967 and 2003 and plant samples from some capture sites. Then we compared stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope ratios to investigate dietary preferences for C₃ or C₄ plants. Mean isotope ratios for C₃ plants we sampled were −26.84‰ (s = 0.17) for δ¹³C and −0.02‰ (s = 0.32) for δ¹⁵N. For C₄ plants, mean isotope ratios for δ¹³C and δ¹⁵N were −15.04 ‰ (s = 0.38) and −0.74‰ (s = 0.55), respectively. Mogollon voles were largely herbivorous based on δ¹⁵N (mean and standard error: 3.77 ± 0.17‰) and used C₃ plants more than C4 based on δ¹³C C (−24.21 ± 0.14‰). Activities that lead to changes in plant species composition or reduction in C₃ plants in montane grasslands and forests (e.g., excessive ungulate grazing) may reduce habitat quality for Mogollon voles.

Interspecific hybridization has increasingly become regarded as a serious threat to the genetic integrity and persistence of rare plants. Oenothera glazioviana (Onagraceae) is a horticultural species that has escaped cultivation and now threatens the narrow Pacific coastal endemic O. wolfii with hybridization. Reports of morphologically intermediate and ecologically aggressive forms prompted this investigation into the extent of hybridization over the range of O. wolfii. In particular, this study identifies populations of pure and hybrid origins. We used multivariate methods to characterize the morphological variation of Oregon and northern California coastal Oenothera populations. Putatively pure O. wolfii and O. glazioviana individuals do not overlap in many floral characteristics. We found morphologies ranging between the 2 species in northern California populations, however, supporting the inference of hybridization. Remote O. wolfii populations in Oregon were smaller in almost all characters, and discriminant analysis was able to distinguish the rare species from both hybrids and O. glazioviana. However, 5 of 10 O. wolfii populations overlapped significantly with hybrid populations for individual traits and composite morphology, and trait values outside the range of O. wolfii were discovered in 2 populations previously considered to be pure. We also discuss the morphological evidence in light of these species' chromosomal complexes and environmental factors.

The benthic macroinvertebrate fauna of southern Saskatchewan, Canada, has received little attention relative to other regions of western North America. Therefore, little is known of the related aquatic ecosystem health and biogeography of regional aquatic insects. Here we present the results of an aquatic macroinvertebrate survey for the Pipestone Creek watershed in southeastern Saskatchewan. We qualitatively sampled aquatic macroinvertebrates in 5 sites on 4 dates through spring, summer, and fall 2006. Sampling produced 294 taxa of macroinvertebrates including 25 provincial range extensions to the southeast corner of the province. Presence/absence data of taxa grouped the sites into lentic and lotic sites. However, the relative proportions of the taxa varied greatly among sites, with no 2 sites having a community similarity greater than 50%. Functional feeding group analyses separated the sites into collector-dominated and scraper/grazer-dominated sites. However, the taxonomic make-up of the feeding groups varied among sites and also among dates. A modified Hilsenhoff Biotic Index of the site communities indicated that all were influenced by organic pollution. Results of this study suggest that although the watershed is enormously diverse, its biological communities are likely influenced by organic pollution. Further, range expansions of species found here, such as the stonefly Perlesta placida, have implications for invasion pathways and post-glaciation species islands in a prairie landscape.

Many rangelands in the southwestern United States provide quality habitat for Northern Bobwhites (Colinus virginianus). These same habitats are frequently managed for livestock production and thus are subjected to various brush management practices that are meant to enhance forage production. Bobwhites rely on woody cover for food, thermal and loafing cover, and protection from avian predators. Implementing brush management practices that reflect bobwhite requirements is important for managing usable space and viable populations. We described the structural vegetative characteristics associated with bobwhite locations and random locations on native rangelands in the upper Rolling Plains of Texas that are dominated by honey mesquite (Prosopis glandulosa) and managed with aerial herbicide and prescribed fire. We also used binary logistic regression to model habitat selection; the initial model was built using 67% of the data (n = 179 used-random paired points) and then validated using the remaining 33% of the data (n = 88 used-random paired points). Locations used by bobwhites had significantly larger mean values of percent brush canopy cover, visual obstruction, and angle of obstruction than did random locations; random locations had a greater mean value of percent bare ground than locations used by bobwhites. The resulting logistic regression model contained only the angle of obstruction; the model had an 80% probability of correctly classifying used and random locations based on the area under the receiver operating curve (ROC). The model maintained a high classification probability when applied to the smaller validation data set, with an area under the ROC of 0.78.

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 and water-quality data were collected concurrently. Chlorophyll-a values ranged from 0.2 to 3.2 mg ·m⁻². Chlorophyll-a in the Bull Creek watershed was generally lower than in the other watersheds. Benthic algal assemblages were dominated by diatoms and cyanobacteria. We collected 79 taxa of diatoms in 2002 and 126 taxa in 2005. Diatom taxa richness in individual samples ranged from 15 to 47. Nonmetric multidimensional scaling analysis of arcsine square-root transformed proportional abundances of diatoms identified 3 groups of sites. Bull Creek sites were generally different from other sites (group 1), and the sites from Bull Creek were different in 2002 (group 2) and 2005 (group 3). Five taxa appeared to be particularly important in distinguishing groups: Achnanthidium minutissimum, Cocconeis placentula, Eunotia incisa, Eunotia pectinalis var. minor, and Planothidium lanceolatum. Elevation, water temperature, pH, specific conductance, and canopy were habitat variables correlated with the differences in diatom assemblages among sites. Our results provide a valuable baseline for future studies of benthic algae in Sierra Nevada headwater streams and will be particularly important in understanding the effects of different forest restoration management strategies being tested in the KREW project.

Leech species of the mid-Snake River of Idaho and Oregon are described, and the distribution of the extant leech Mooreobdella microstoma Moore in the Snake River paleodrainage is delineated. Samples were collected from aquatic surveys in the Snake River using suction dredging by the Idaho Power Company and U.S. Bureau of Reclamation between 1995 and 2006. Supplementing these surveys, opportunities were provided for leech identification in water-quality analyses in Arizona and Wyoming and in other surveys in California, Oregon, Washington, and Idaho. Eight species of leeches were found in the Snake River surveys. Erpobdella parva Moore was the most widely distributed species, occurring both above and below Shoshone Falls. Mooreobdella microstoma was widely distributed below Shoshone Falls. Other leech species were rare, although Helobdella stagnalis Linnaeus was very common above and less common below Shoshone Falls, a natural barrier to the anadromous fish. Mooreobdella microstoma is an extant species that links the Snake River to the lower Colorado River by various paleodrainages. It probably colonized the Snake River by upstream movement, whereas Erpobdella parva likely colonized this river by downstream movement.

Although polyploidy can alter host plants in important ways (e.g., size, phenology, resource use, and ecological range), little is known about the effects of polyploidy-associated changes on plant-insect interactions. The presence of Campiglossa footeorum Novak (Diptera: Tephritidae) and its effect on its host plant Arnica cordifolia Hook. (Asteraceae) were monitored throughout Colorado, where triploids and tetraploids of the host plant occur. Campiglossa footeorum is more abundant in sites with more tetraploids and attacks tetraploids more than triploids. Polyploidy could be an important force shaping the current evolutionary trajectory of the plants and insects in this system. Campiglossa footeorum is intimately linked to A. cordifolia, and polyploidy should be included in any assessment of the insect's population dynamics.

The structure of grassland communities can vary widely in response to heterogeneous habitat variables. In this study we document plant communities, soil types, and site characteristics for 12 Palouse prairie remnants in southeastern Washington and northern Idaho. We used general linear models to test the predictive value of 6 biophysical variables (slope, aspect, distance from edge, edge type, vegetation structure, and soil type) on 3 plant community metrics: species richness, Simpson's diversity index, and the dominance of exotic species. From full models including all variables, we used Akaike's information criterion (AIC) to select the best model for each metric. Aspect and vegetation structure were significant predictors of species richness (R² = 0.08) and diversity (R² = 0.09), while aspect, soil type, distance from edge, and edge type (type of adjacent matrix habitat) influenced the dominance of exotic species (R² = 0.28). Additional soil sampling determined that the depth to a restrictive layer also had significant impacts on the dominance of exotic species (R² = 0.31). This study confirms that biophysical characteristics influence Palouse prairie plant communities and may help set research and conservation priorities for isolated and uninventoried remnants.

The present study analyzed the stomach contents of 65 Great Basin spadefoot toads, Spea intermontana (Cope), collected in an area of irrigation runoff in south central Washington State. Toads were collected by pitfall trapping. Traps were maintained for 1 year beginning in April 2002. Toads consumed at least 56 different arthropod taxa belonging to the orders Coleoptera, Diptera, Hemiptera, Hymenoptera, Lepidoptera, Neuroptera, Orthoptera, Trichoptera, Collembola, and Araneae. Ants and darkling beetles were among the most common prey. Feeding appeared to be very generalized with the toads accepting almost anything they could capture and subdue.

Prairie dog eradication negatively affects dependent wildlife. Assessing the effects of prairie dog activities on reptiles and amphibians may depend upon the efficacy of trapping designs. We compared capture rates of reptiles and amphibians on black-tailed prairie dog (Cynomys ludovicianus) colonies and on adjacent uncolonized short-grass prairie, using funnel traps and pitfall traps with drift fences, as well as ground captures. We captured 152 reptiles and amphibians representing 10 species. We captured 51.3% of all reptiles and amphibians on colonies, compared to 48.7% from uncolonized sites. Overall, captures of reptiles and amphibians were similar on colonies and uncolonized sites for all capture methods combined. We achieved higher capture rates on uncolonized sites using funnel traps and pitfall traps but higher capture rates on colonies for ground captures. For all years on all sites combined, we captured significantly more animals in funnel traps (52.6%), surpassing pitfall trap captures (23.0%) and ground captures (24.3%). We recommend using multiple Y-shaped drift fence arrays ≥ 7.6 m in length, funnel traps with double-ended openings, and black-colored pitfall traps with opening diameters ≥ 30 cm.

The diamondback moth (Plutella xylostella [L.]), is one of the most economically important pests of cruciferous plants throughout the world, causing economically significant damage in broccoli, cabbage, canola, collards, and mustard. In Canada, P. xylostella is an important economic pest of canola (Brassica napus L. and Brassica rapa L.). In North America, the diamondback moth has been collected as far north as Edmonton, Alberta, Canada. Despite its wide distribution and presence at economically damaging levels in Canada, there have been no published reports of P. xylostella from Alaska. This note documents the 1st collection of this pest species in interior Alaska. With continued moderation of the climate due to global climate change, this species has the potential to become an increasingly important agricultural pest in the state.

Swift foxes (Vulpes velox) are shortgrass specialists and as a result are heavily dependent upon grassland disturbance regimes to maintain high-quality habitat. To better understand this relationship, we monitored the movement and spatial ecology of resident swift foxes before and after a 2005 prescribed burn in southeastern Colorado. We hypothesized that foxes would shift home ranges into and increase foraging activity within the prescribed burn area. Foxes did appear to alter their space-use patterns in response to the burn, although the response was constrained by territoriality. Foxes whose core-use areas overlapped the burn increased their use of the burn area for foraging and denning, but we did not observe shifts of individual home ranges to encompass more of the burned area. Foxes whose core-use areas did not overlap the burn did not alter their space use or change home range boundaries in response to the burn. Because we observed only positive or neutral responses to prescribed burning, we recommend this tool as an appropriate method to maintain high-quality swift fox habitat.

Many snakes employ tail movements to attract prey, but this behavior is rare in lizards. Use of caudal movements to distract prey, however, is rare in all squamates. Recently, caudal movements in a Sceloporus occidentalis individual immediately prior to attempted prey capture were documented. We supplement this sole documentation of caudal movements in S. occidentalis with additional field observations. Additionally, video footage of the behavior was recorded on 2 occasions. From these additional observations, we hypothesize that this behavior might serve to distract prey.