The reliability of monitoring visual obstruction and estimating standing herbage with a modified Robel pole was examined for high-elevation meadows in sedimentary soils on the Bighorn National Forest, Wyoming. Our objectives were to (1) test a modified pole graduated with 1.27-cm (0.5-inch) bands for estimating standing herbage based on linear regression of visual obstruction readings (VORs) on standing herbage, (2) validate the derived regression, (3) provide sample size estimates, and (4) develop guidelines for monitoring mountain grasslands. Each transect had 20 visual obstruction stations spaced 10 meters apart with 4 visual obstruction readings at each station. At 4 stations, vegetation within a 0.25-m² area was clipped at ground level. VORs and clipped standing herbage were averaged by transect for analysis. Visual obstruction reliably predicted average standing herbage (dry weights) for mountain meadows (r² = 0.81, s_𝑥̄= 382 kg ·ha⁻¹). Standing herbage ranged from 387 kg ·ha⁻¹ to 3930 kg ·ha⁻¹, with a mean of 1742 kg ·ha⁻¹. A validation data set of 13 transects sampled across the range of variation in standing crop showed that 85% of transects fell within the 90% prediction limits. We recommend a minimum of 4 transects for monitoring key areas or small areas up to 259 ha (640 acres) when managers need to consider differences in VOR bands and address multiple objectives. Cluster analyses (ISODATA) applied to the pole readings resulted in 4 visual obstruction categories: short, short-intermediate, tall-intermediate, and tall. This tool provides a simple, reliable, and cost-effective (time-saving) alternative to clipping vegetation and obtaining dry weights for monitoring.

The central tenet of island biogeography theory—that species assemblages on islands are functions of island area, isolation from mainlands, and vicariance—has been altered by the demonstrable effects that rapid climate change is imposing on insular faunas, at least in isolated mountaintops. Although populations of American pikas (Ochotona princeps) continue to suffer extirpations, and although the lower bounds of the pika's elevational distribution are shifting upslope across the Great Basin, we report here on the new discovery of a low-elevation population of pikas in a mountain range from which they had not been reported previously. This discovery, particularly in the context of relatively rapid ecological change, highlights the importance of seeking out original sources of information and performing spatially extensive fieldwork. Results presented here further illustrate that although thermal influences appear to be the single strongest determinant of pika distribution currently, such influences interact with a number of other factors to determine persistence.

I conducted laboratory experiments and fit a response surface regression model to evaluate growth of endangered razorback sucker (Xyrauchen texanus) up to 37 days post-hatch. Fish growth at ad libitum ration was positively related to water temperature, and larvae reared at 25.5°C grew about twice as fast in length and 4 times as fast in weight as those at 16.5°C. Growth was intermediate at 19.5°C and 22.5°C. Time required for razorback sucker larvae to exceed 25 mm total length (TL), a potentially important threshold for reduced predation, was 30 days (post-hatch) at 25.5°C, 33 days at 22.5°C, 36 days at 19.5°C, and 41 days at 16.5°C. Time to exceed 25 mm TL increased to 52 days under a low growth rate of 0.29 mm ·d⁻¹. Faster growth rates could reduce the time that razorback sucker larvae are vulnerable to predation by abundant and co-occurring small-bodied fish and invertebrate predators in nursery areas. Growth of razorback sucker larvae could be enhanced if flow re-regulation at Flaming Gorge Dam and downstream levee removal restored connections between the Green River and its floodplain and increased availability of warm and productive wetlands.

In North America, Nebraska represents part of the northwestern edge of the distribution for the evening bat (Nycticeius humeralis). To date, little information on this bat's natural history has been published from the state or from other parts of the Great Plains. Here we report on aspects of its natural history in Nebraska from 2 localities. In late summer and early autumn of 2006, we documented individuals farther west in Nebraska (Harlan County) than previously reported and determined that individuals fed mainly on Coleoptera and Hymenoptera. In 2006, evening bats appeared to migrate from Nebraska during late September–early October, and individuals were extremely fat, about 15 g, prior to migration. Evening bats likely are more widespread and common in south central Nebraska than previously documented. On 6 October 2005, we reported on an individual from eastern Nebraska (Douglas County), which represents the latest seasonal record of N. humeralis from the state.

We compared winter (December, January, and February) and early spring (March and April) bird communities among 4 successional stages that included grassland, shrubsteppe, juniper-shrubsteppe, and old-growth juniper woodland in central Oregon. Birds were surveyed monthly from December through April in 1998/1999 and 1999/2000 using the point count method to estimate relative abundance of birds (individuals · transect⁻¹year⁻¹). We used distance sampling to correct for potential bias in estimating abundance and density among successional stages. A total of 4513 birds (32 species) were detected. Relative abundance of total birds (all species combined) was similar in the juniper-shrubsteppe and old-growth woodland (48.7 and 48.9 individuals · transect⁻¹, respectively) but 6 times greater than in the grassland and shrubsteppe (8.0 and 7.7 individuals · transect⁻¹, respectively) during the 5-month period. Total density of birds was greater in old-growth juniper woodland and juniper-shrubsteppe than in grassland or shrub-steppe. However, median bird species richness in 1998/1999 was highest in grassland and lowest both in shrubsteppe and juniper-shrubsteppe, and in 1999/2000 it was highest in shrubsteppe and lowest in juniper-shrubsteppe and old-growth juniper woodland. American Robins and Townsend's Solitaires were the most abundant species in juniper-shrubsteppe and old-growth juniper woodland during the winter months. Sage Sparrows and Horned Larks were the most abundant species in shrubsteppe during winter, and Horned Larks were most abundant in grasslands during the early spring transition period prior to nesting. Our results indicate that a different suite of species use these successional stages during the nonbreeding season. If avifauna conservation is a part of long-term management goals, a broad range of successional stages should be maintained on the landscape to provide habitat for a variety of avian species throughout the year.

Two subspecies of the big brown bat (Eptesicus fuscus) are reported to occur in Nebraska. The eastern race, E. f. fuscus, is reportedly bigger and darker than its western counterpart E. f. pallidus. Where these 2 subspecies come in contact is the subject of debate. We used external, cranial, and colorimetric data to investigate geographic variation among populations of E. fuscus in Nebraska to determine the location of the zone of contact between E. f. fuscus and E. f. pallidus. We discovered significant variation in external, cranial, and colorimetric data, suggesting that E. fuscus is represented by 2 subspecies in Nebraska. Our results showed that E. f. pallidus is smaller, possesses lighter pelage, and is restricted to the northern and western parts of Nebraska, whereas E. f. fuscus is larger, possesses darker pelage, and occurs in southern and southeastern parts of the state. Populations located between these regions represent intergrades of the 2 subspecies. We suggest that the subspecific boundary represents a broad zone of integration running in a northeast to southwest direction and may reflect the position of temperature and precipitation clines.

The demography of a population of Yarrow's spiny lizard, Sceloporus jarrovii, was examined from 2004 to 2006 in the canyon Las Piedras Encimadas, located in Gomez Palacio, Durango, México. Lizards were studied using a mark-recapture technique. Reproduction in females occurred between November and May, coinciding with dry conditions. Reproductive activity was highest (percent of females with vitellogenic follicles or embryos) in the middle of the dry season (November and December). Thirteen percent of females reached sexual maturity at an average age of 8.5 months. The population structure was similar in spring and fall, but not in summer. A notable feature of summer, coinciding with the wet season, was the greater number of hatchlings and juveniles. The overall sex ratio did not differ from 1:1. The density of adults varied from 12 to 62 animals ·0.5 ha⁻¹. Temperate and arid-adapted populations of S. jarrovii exhibited broad similarity in timing of the reproductive season, whereas factors such as density, growth, age at sexual maturity, and survivorship differed.

In the early years of his research on the native trouts of western North America, Behnke (1960, 1966, 1979) observed consistent differences in certain meristic characters between the cutthroat trout of the Humboldt River drainage and those from the Truckee, Carson, and Walker river drainages of the Lahontan Basin, and proposed that the Humboldt trout be recognized as a distinct subspecies. He coined the subspecies name humboldtensis, but a formal description was never published. Here we again present the early evidence for subspecific distinction of the Humboldt drainage cutthroat trout, and add more recent findings from the fields of population genetics and Pleistocene and recent zoogeography that support this interpretation. Based on this evidence, we offer a formal description of the cutthroat subspecies Oncorhynchus clarkii humboldtensis and map its likely historical distribution. Available meristic and zoogeographic evidence indicates that the native trouts of the upper Quinn River, Nevada and Oregon and the Coyote Basin of Oregon should be included with humboldtensis as well.

Maguire primrose is a locally endemic plant of northern Utah, USA, with a total known range of less than 20 km². A previous study found evidence for strong differentiation among local populations at 4 allozyme loci. Here we reexamined populations using 165 AFLP loci and found further evidence of unusually strong genetic structure. We also found an apparently fixed nucleotide difference between populations for a noncoding region of chloroplast DNA, mirroring the patterns seen for AFLP loci. Furthermore, we tested the hypothesis that the current population structure is the result of breeding barriers between plants from different populations. We made controlled hand-pollinated crosses and found that interpopulation crosses did not set significantly fewer seeds than intrapopulation crosses. Thus, we found no evidence of breeding barriers to explain these genetic patterns. However, we did note a relatively short overlap in flowering time, suggesting that phenology is a more feasible explanation for genetic differentiation than pollen-stigma incompatibility. Our study emphasizes that even locally endemic plants can house measurable genetic differences over a short geographic scale.

From 1996 to 2004, we studied population dynamics of a rodent assemblage in semiarid habitats in Lassen County, California. Abundances of rodents appeared affected by fluctuations in precipitation from a high in 1996 to average and slightly below-average levels in subsequent years; perhaps reflecting this, assemblage composition also changed dramatically during the study period. California kangaroo rats (Dipodomys californicus) declined from abundant to extremely rare, abundances of deer mice (Peromyscus maniculatus) fluctuated greatly during the study period, and, perhaps most notably, populations of dusky-footed woodrats (Neotoma fuscipes) appeared to decline to local extinction, possibly allowing for the subsequent colonization of desert woodrats (N. lepida). These changes appeared to represent natural variation in numbers and composition in an ecologically dynamic ecotonal region in response to multiyear changes in precipitation.

We examined the biogeographic patterns of ground-dwelling arthropod communities across a heterogeneous semiarid region of the Southern Rio Grande Rift Valley of New Mexico. Our 3 sites included portions of 5 ecoregions, with the middle site a transition area where all ecoregions converged. We addressed the following 3 questions: (1) Do the species assemblage patterns for ground arthropods across habitats and sites conform to recognized ecoregions? (2) Are arthropod assemblages in distinct vegetation-defined habitats within an ecoregion more similar to each other or to assemblages in similar vegetation-defined habitats in other ecoregions? (3) Is there a detectable edge effect with increased arthropod diversity in the area of converging ecoregions? We encountered 442 target arthropod species from pitfall traps operating continuously for 7 years over a series of different habitats at each of the 3 sites. We examined geographic distributions of spider and cricket/grasshopper species in detail, and they showed affinities for different ecoregions, respectively. Each habitat within a study site supported a unique overall arthropod assemblage; nevertheless, different habitats at the same site were more similar to each other than they were to similar habitats at other sites. Overall arthropod species richness was greatest in the area where all 5 ecoregions converged. Arthropod species and their geographic distributions are poorly known relative to vascular plants and vertebrate animals. Findings from this research indicate that ecoregional classification is a useful tool for understanding biogeographic patterns among arthropods.

Invasive species are of concern to natural resource managers and conservation biologists. The New Zealand mudsnail (Potamopyrgus antipodarum) has invaded many freshwaters of the western United States with unknown consequences on the native benthic invertebrate fauna. We conducted a laboratory investigation to determine if mudsnails affected the growth of the desert valvata snail (Valvata utahensis), a species native to the Snake River in southern Idaho. Results indicated that increasing densities of mudsnails limited the growth rate and absolute growth of the desert valvata. We suggest that absolute growth is a better metric than growth rate for comparing snail species and assessing interactions between them.

In the desert Southwest, migrating birds have been documented using upland habitat and xeroriparian washes as well as riparian areas. Yet aside from the river corridors, natural water sources (e.g., natural rock tanks [tinajas], springs, and ephemeral washes) in upland areas are scarce. Because of this scarcity, state and federal resource managers augmented water sources throughout the Southwest by constructing permanent wildlife water developments with the intention of enhancing game populations. However, despite these increases in free-standing water, there is a paucity of information on the use of water by birds during migration. Our objectives were to document use of these wildlife water developments by resident and migratory songbirds and assess the effectiveness of monitoring these species using remote color videography. We placed color video cameras at 2 wildlife water developments in southwestern Arizona during the spring and fall of 2004. Although we observed more use by migrants during spring than fall, overall use by migratory birds was low. However, the wildlife water developments were frequently used by resident birds. Remote videography provided continuous information on daily and seasonal patterns of bird use at wildlife water catchments with negligible disturbance by observers, yet for passerines, we felt that the benefits of remote videography did not justify the high cost of equipment purchase, installation, maintenance, and data processing.

The black-tailed prairie dog is an important component of prairie and steppe ecosystems. Currently many prairie dog colonies are fragmented by, or adjacent to, urban development, but little is known about what effects urbanization may have on these animals. I compare body weights and sex ratios of prairie dogs in isolated urban habitat in Denver, Colorado, to published data for black-tailed prairie dogs at the same time of year. Prairie dogs in this study had summer weights similar to those reported in the literature, although males apparently gained weight earlier in the year, and observed sex ratios were not significantly different from 1:1. Although prairie dogs in urban areas face numerous threats, my study provides no evidence that urban forage is limited enough to result in decreased body mass or skewed sex ratios of urban prairie dogs.

The spotted bat (Euderma maculatum) is an elusive and rarely captured species in western North America. In the United States, it is known from 12 western states. In New Mexico, few individuals have been reported in recent years, and multiple individuals are known from 9 of 12 capture sites. This study reports on additional captures of E. maculatum from Mt. Taylor (Cibola County) for 2 consecutive summers and includes evidence of a reproducing population in the area. On 30 June/1 July 2006, I captured 4 individuals of E. maculatum, including a lactating female, and on 5 June 2007, I captured a nonreproductive female. The flight of this species was directional and deliberate; I captured 5 of 6 spotted bats that came low over the earthen pond. This study demonstrates how human-made sources of water in an arid region provide opportunities for many species of bats to drink.

Peromyscus nasutus has been considered to occur in Utah since it was first reported in the state in 1935. Authors since then have considered the distribution of P. nasutus to include southeastern Utah. However, the original Utah specimen was later reidentified as Peromyscus boylii. A query of museums revealed only 1 other specimen considered to be P. nasutus from Utah. This specimen was examined and found to be P. boylii. Thus, there is no evidence of the occurrence of P. nasutus in Utah, and the northwesternmost accepted records of this species are in the Chuska Mountains of northeastern Arizona.