Composite soil samples from 7 sites on San Nicolas Island were evaluated quantitatively and qualitatively for the presence of cyanobacteria and eukaryotic microalgae. Combined data demonstrated a rich algal flora with 19 cyanobacterial and 19 eukaryotic microalgal genera being identified, for a total of 56 species. Nine new species were identified and described among the cyanobacteria and the eukaryotic microalgae that were isolated: Leibleinia edaphica, Aphanothece maritima, Chroococcidiopsis edaphica, Cyanosarcina atroveneta, Hassallia californica, Hassallia pseudoramosissima, Microchaete terrestre, Palmellopsis californicus, and Pseudotetracystis compactis. Distinct distributional patterns of algal taxa existed among sites on the island and among soil algal floras of western North America. Some algal taxa appeared to be widely distributed across many desert regions, including Microcoleus vaginatus, Nostoc punctiforme, Nostoc paludosum, and Tolypothrix distorta, Chlorella vulgaris, Diplosphaera cf. chodatii, Myrmecia astigmatica, Myrmecia biatorellae, Hantzschia amphioxys, and Luticola mutica. Some taxa share a distinctly southern distribution with soil algae from southern Arizona, southern California, and Baja California (e.g., Scenedesmus deserticola and Eustigmatos magnus). The data presented herein support the view that the cyanobacterial and microalgal floras of soil crusts possess significant biodiversity, much of it previously undescribed.

Myotis lucifigus and Myotis yumanensis are 2 species of bats subject to potentially high rates of misidentification because they are often difficult to differentiate in the hand under field conditions. We tested the utility of a suite of external morphological characteristics frequently cited in regional keys to differentiate the 2 species in the field. Forearm length, dorsal pelage sheen, ear color, and forehead slope were examined from 101 bats captured in central Oregon during 2002–2003. Post hoc genetic analysis was performed on tissue samples collected from the 101 bats to confirm identification. Forearm lengths overlapped considerably between species. Only 18% of M. yumanensis and 17% of M. lucifugus were correctly identified with probability ≥95% using forearm length alone. Pelage sheen, ear color, and forehead slope successfully identified 96%, 82%, and 77% of individual bats, respectively. When forearm length was considered together with other traits, identification rates ranged from 92% to 20%. Ability to correctly identify M. yumanensis was 2–6 times greater than for M. lucifugus. Pelage sheen was useful in our study; however, using this character required a subjective decision from the observer, and the result often contradicted other characters for species identification stated in regional keys. For these reasons, we recommend that morphological features be used judiciously and only as supportive criteria for field identification in combination with voucher echolocation calls and genetic confirmation.

We conducted a 4-year experiment to assess the impacts of rotational cattle grazing on rodents and raptors in a mesic coastal grassland in northwestern California. Live-trapping indicated that rodent abundance declined by 69% on the grazed area and increased by 14% on the ungrazed area. Raptor use of the grazed area declined by 15% and increased on the ungrazed area by 63%. Measures of giving-up density indicated that rodents perceived a 25% higher predation risk on grazed area than on ungrazed area, but raptor hunting surveys indicated that risk of depredation from raptors was 2.5 times lower in the grazed habitat, suggesting that rodents use indirect vegetative cues to assess risk.

The frequency and intensity of wildfire in the western United States has increased over the last century, creating a heterogeneous mosaic of landscapes in various stages of recovery. The 2002 Hayman Fire was one of the largest wildfires in Colorado history and was unprecedented for its speed and intensity, with over 50%–70% of the burn area classified as moderate to high severity where much of the canopy crown was consumed. We evaluated the short-term impact of the Hayman Fire on ecological properties in montane stream ecosystems in the summers of 2003 and 2004, one and two years post-fire. Fire significantly altered surface temperature, dissolved oxygen concentration, and the chemical composition of stream water, including concentrations of nitrate, phosphate, and mineral salts. However, fire did not have significant impacts on stream conductivity, pH, or total concentrations of cations or anions during our study period. Streams in the burn area contained fewer benthic macroinvertebrate taxa compared to unburned streams during the year after fire and contained lower invertebrate densities and biomass compared to reference streams 2 years post-fire. Average C:N ratio of the benthic macroinvertebrate community was significantly and negatively related to stream nitrate concentration, possibly due to a shift in community composition or invertebrate nitrogen acquisition in fire-affected streams.

We examined optimal temperatures for growth and the upper thermal tolerance of juvenile northern leatherside chub (Lepidomeda copei). We conducted 2 experiments using the acclimated chronic-exposure method to estimate optimal temperature for growth of age-0 northern leatherside chub (range 12.8–28.3 °C). Upper thermal tolerance was estimated using the critical thermal maximum (CTM) and upper incipient lethal temperature (UILT) methods for fish acclimated at 15, 18, 23, and 28 °C. We also measured stream temperatures in Yellow Creek, Summit County, Utah, during July–August 2006 to compare our results to actual summer stream temperatures. Survival in growth tests was not significantly different between treatment temperatures in either experiment (P > 0.098). The optimal temperature for growth in the 1st trial estimated from the 2nd-order polynomial regression was 23.0 °C, falling outside the range of experimental temperatures (12.8–22.2 °C). The estimated optimal temperature for growth in the 2nd trial was 23.2 °C. In the upper thermal tolerance tests, juvenile northern leatherside chub had CTM values between 29.6 and 35.0 °C; CTM values increased as acclimation temperature increased. Upper incipient lethal temperatures (LT₅₀) ranged from 26.5 to 30.2 °C, increasing with acclimation temperature. Summer stream temperatures in Yellow Creek had a lower mean (14.0–18.1 °C) than did the optimal temperature for growth determined in these studies, but these temperatures exhibited diel fluctuations as large as 15.7 °C.

The June sucker (Chasmistes liorus) is an endangered lake sucker endemic to Utah Lake, Utah. As part of recovery actions, June suckers were introduced into Red Butte Reservoir, Utah, as a wild grow-out site. Since their introduction, June suckers have successfully reproduced in Red Butte Reservoir, producing a large population in this refuge. I used passive egg collectors (egg traps and nets) and observational surveys to determine the location of spawning sites within the reservoir, and larval light trapping to determine successful recruitment (i.e., egg survival through larval swim-up) at these sites. Eggs were collected between 18 June and 15 July at 2 general sites along or near the reservoir's dam, although spawning was only observed at 1 of these sites. Suckers were not observed at, and eggs were not collected in or around, the mouth of Red Butte Creek as expected. At the site where spawning was observed, suckers were spawning over gravel substrates (mean diameter = 32 mm) at depths of 0.5–1.75 m. At the other site, suckers were spawning over silt/clay substrates (mean diameter < 1 mm) at depths of 1.1–4.75 m. Larval suckers were first captured along the dam where spawning was observed and eggs were captured, demonstrating that successful recruitment occurred at this spawning site. Larval suckers were never captured at the mouth of Red Butte Creek, confirming egg collecting data and observations that suckers did not utilize the stream for spawning. This June sucker refuge population is supported by lacustrine spawning, an important finding for management and recovery of this species.

Previous research suggests that the yellow-faced pocket gopher (Cratogeomys castanops) occupies a restricted range in western Kansas that is surrounded by the range of the plains pocket gopher (Geomys bursarius), which is regarded as a superior competitor. To determine whether the plains pocket gopher has encroached on the range of the yellow-faced pocket gopher in the past 35 years and to better understand the geographic relationships of these species, we trapped pocket gophers in western Kansas and collected soil texture and land cover data. We used ArcView 3.2 to map the distributions of these species in the study area, as well as the kinds of soil and land cover found in their potential home ranges. Although the distributions of the 2 species overlap, they are strictly parapatric. The apparent cause of this parapatric relationship is differential tolerance of soil textures. The distribution of the yellow-faced pocket gopher in Kansas is limited to just 7 counties divided into 2 populations, both surrounded by the distribution of the plains pocket gopher. We found no evidence that the range of the plains pocket gopher has expanded at the expense of the yellow-faced pocket gopher in the past 35 years. Thus, although the yellow-faced pocket gopher remains a “species of greatest conservation need” in Kansas because of agricultural threats, it evidently is not imperiled at this time.

While clones of trembling aspen (Populus tremuloides, Michx.) in the Intermountain West of North America are expected to be large, one putative genet in central Utah, identified from morphological evidence, has garnered particular attention for its size, even gaining the nickname “Pando” (Latin for “I spread”). In order to determine if a single genetic individual coincides with the morphological boundary of “Pando,” we sampled 209 stems on a 50-m grid throughout the putative clone for analysis at 7 microsatellite loci. We have identified a single genetic entity concurrent with that described from morphological characteristics. Spatial analyses indicate that the clone covers approximately 43.6 ha. Surprisingly, an additional 40 genotypes were identified adjacent to the putative clone, indicating that genet diversity may be high in the stand as a whole. In confirming the existence of the “Pando” clone, we suggest that this organism will provide valuable opportunities to study important biological processes such as clonal growth, somatic mutation, and senescence.

The historical and environmental forces involved in determining the geographic location of plant hybrid zones have long been of interest. Often hybrid zones appear to be intimately tied to the environment, yet because many abiotic factors covary it is often difficult to understand which are truly the most important in maintaining the position and structure of a hybrid zone. This study uses empirical data and modeling analyses to examine whether abiotic factors are responsible for the location and structure of an oak (Quercus) hybrid zone and, if so, which factors are the most important. Specifically, leaf trait measurements and ecological niche models were used to test the hypothesis that water availability plays a primary role in promoting and maintaining the location of hybridization between 2 species. Leaf trait analyses and ecological niche models both supported the hypothesis that water availability determines the location and structure of the hybrid zone. These findings lend support for the general importance of environmental factors in determining hybrid zone location and structure. Furthermore, they demonstrate how functional trait analyses and predictive ecological niche models can be used in future hybrid zone research.

The Wood River sculpin Cottus leiopomus is endemic to the Wood River Basin in central Idaho and is a nongame species of concern because of its limited distribution. However, status and genetic population structure, 2 factors often central to the conservation and management of species of concern, have not been assessed for this species. We used backpack electrofishers to survey streams that were small enough (i.e., <10 m wide) to collect quantitative distribution and abundance data for Wood River sculpin, and we used mitochondrial DNA control region sequencing to investigate the distribution of genetic variation across the species' range. Of the 102 study sites surveyed, 20 sites (20%) had Wood River sculpin present, including 50%, 15%, and 0% of the sites predicted a priori to contain, possibly contain, or not contain the sculpin, respectively. Native redband trout Oncorhynchus mykiss gairdneri were present at 21 study sites, including 18 of the 20 sites that contained Wood River sculpin. Sixty-one study sites (60%) were dry or had too little water to contain any fish. We estimated that a minimum of 1.36 million Wood River sculpin (≥20 mm total length) currently reside in the basin. The presence of Wood River sculpin was positively associated with stream width:depth ratio and percent cobble/boulder substrate and negatively associated with stream gradient. Mitochondrial DNA haplotype differences were observed between and within the 3 major river subbasins supporting sculpin, with the most striking differences observed between populations in the Camas Creek subbasin and the other 2 subbasins, among which no haplotypes were shared, suggesting relatively long-term isolation. Our results suggest that the Wood River sculpin remains relatively widespread and abundant within its endemic range, despite obvious changes in historical stream connectivity caused by irrigation diversions and other chronic habitat alterations.

We examined the diet and sexual dimorphism of the desert iguana, Dipsosaurus dorsalis, from Sonora, Mexico. The diet consisted primarily of vegetation, with insect material contributing little to the overall volume of the diet. Plant matter was restricted to leaves and seeds. Animal prey consisted mostly of ants, termites, and beetles. Males and females did not differ significantly in snout–vent length, head length, or head width. These results confirm that in general D. dorsalis is herbivorous and not sexually dimorphic through much of its range.

Gizzard shad (Dorosoma cepedianum) were introduced into the Colorado River Basin circa 1996 via an unintentional contaminated stocking. Gizzard shad were collected throughout much of the Upper Colorado River Basin in 2005, 2006, and 2007. These collections document a rapid range expansion of this introduced species and a threat to intact fisheries.

We studied the white-tailed antelope ground squirrel during spring and summer 2006 to determine young-of-the-year and adult sex ratios in the Indian Wells Valley, San Bernardino County, California. We calculated a young-of-the-year sex ratio of 1.45:1 (female to male), whereas the adult sex ratio was approximately 1:1. Our young-of-the-year sex ratio was greater than the 1.1:1 (female to male) natal sex ratio previously reported. Differences between young-of-the-year and adult sex ratios may represent low female young-of-the-year survivorship in the Indian Wells Valley.

In the American Southwest, the red squirrel (Tamiasciurus hudsonicus) occurs as disjunct populations in coniferous forests on mountaintops. There is a paucity of information concerning the species' distribution and habitat in western New Mexico. I report new records that document and verify the occurrence of red squirrels in additional montane areas in west central New Mexico, including the Mangas Mountains, Canovas Rim, Turner Mountain, Tularosa Mountains, Elk Mountains, Bearwallow Mountain, and Pinos Altos Mountains. I also report observations of red squirrels from an atypical habitat—low-elevation riparian forests. These new records suggest that the geographic distribution of the species in west central New Mexico is broader than indicated by existing records. However, I also document the apparent extirpation of red squirrels from the Zuni Mountains in northwestern New Mexico. The red squirrel is one of several avian and mammalian species associated with mixed coniferous forests that have become extirpated in this mountain range.