Life history data for Pahrump poolfish (Empetrichthys latos latos) collected from 1937 to 1975 were organized and analyzed to improve our understanding of changes caused by human habitat disruption and introduced goldfish (Carassius auratus) at Manse Spring, Nevada. Pahrump poolfish twice demonstrated their ability to recover numerically from a population crash. The first crash followed a November 1961 introduction of a few goldfish and subsequent removal of vegetation by local ranch children intent on turning Manse Spring into a swimming hole. The second crash followed another major habitat disturbance resulting from an unsuccessful attempt to eradicate goldfish in July 1967. Each crash (1962–1963 and 1967–1968) reduced the poolfish population to fewer than 50 adults and was followed by a population recovery to more than 1000. Following the first habitat disruption, changes in poolfish population structure and poolfish diet were observed. These changes caused an increased mortality rate, resulting in disappearance or decline in relative abundance of larger poolfish size classes with a commensurate reduction in production of mature eggs by the population. We detected no additional changes in life history characteristics that could be associated with the second population crash and recovery. We concluded that removal of vegetation in the summer of 1962 and the more extreme habitat disruption and fish handling in June–July 1967 were human-induced pulse disturbances resulting in poolfish population crashes. We also concluded that the changes in poolfish life history characteristics resulted principally from press disturbances attributable to goldfish.

On Datil [Turner] Island in the Gulf of California, we rediscovered a population of Neotoma varia, previously thought to be extinct. We captured 5 specimens: 1 was kept as a voucher, and 4 were examined and released. Analysis of previous surveys indicates that N. varia is not common on the island and occupies a very restricted range.

The European earwig, Forficula auricularia L., was surveyed using pitfall traps at 3 sites at the Hanford Reach National Monument in south central Washington State. Pitfall traps were collected weekly from April 2002 through April 2003. The earwig was consistently taken during all months of the year at a disturbed, weedy site along the Columbia River (White Bluffs Ferry site) but was rare or not collected in 2 less-disturbed shrubsteppe habitats. Highest numbers occurred during April–May, when immatures accounted for the majority of the catch; immatures reached the adult stage during mid-July, and the species is univoltine at the site. Possible reasons why earwigs have not colonized the monument's shrubsteppe habitat include the arid climate with lack of available moisture, especially for breeding purposes, and a lack of burrow sites.

Records of Wood River sculpin (Cottus leiopomus) from 1893 to 2003 were examined and new data were gathered in 2004 and 2006 to estimate the species' historical range and to search for evidence of changes in its occurrence. Detections of Wood River sculpin were reported in 49 subwatersheds, primarily in the Idaho Batholith ecoregion. The remainder of the Wood River basin was classified as either potential historic range or unknown. Mark-recapture sampling was conducted to estimate the efficiency of electrofishing as a method to detect this sculpin. Sampling efficiency was calculated for 1 upstream pass and 1, 2, and 3 bidirectional passes. A mean sampling efficiency of 45.9% (range 15.4%–63.0%) was achieved using 3 bidirectional passes, block nets, and 0.942 minutes of electrofishing per m² of stream surface. Efficiency declined an average of 38% between electrofishing passes. The rates and reduced efficiencies observed between passes suggest that multiple passes and visits are needed to reliably estimate sculpin presence or absence.

Carnivore consumption of fruit is a principle means by which many fleshy-fruited plant species achieve long-distance seed dispersal. We examined carnivore dispersal of hollyleaf cherry (Prunus ilicifolia) seeds, specifically assessing the survival, desiccation sensitivity, and germination of seeds found in bear scats. Studies were conducted both in the laboratory and in 2 burn areas in Los Padres National Forest, California. Bear scats containing P. ilicifolia seeds were collected in burned and unburned chaparral. We counted seeds in each scat and noted whether endocarps had tooth punctures or rattled audibly when shaken. For comparative germination trials, we also collected fruits and seeds directly from mature shrubs. In the laboratory, following a cold-moist stratification period, seeds were assessed for germinability. In the field, we compared desiccation rates and germinability of seeds from bear scats and freshly collected seeds. We compared rates of moisture loss and germination for seeds subjected to several different conditions, including 25 °C (room temperature), 30 ^°C and 65 °C (in the lab), and placement on exposed soil in a burn area (in the field), where midday temperatures were approximately 45 °C but likely much higher by late afternoon.

Prunus ilicifolia seeds collected from bear scats were largely undamaged; the vast majority of these seeds germinated. In some cases, germination rate was higher for seeds from scats than for seeds from intact fruits. Several results indicate that desiccation is an important cause of reduced germinability. First, seeds that rattled audibly germinated poorly; and the louder the rattle, the lower the germination percentage. Second, seeds (both fresh and those from bear scats) placed in the field under protective screens had greatly reduced levels of germination (an 84% decline) after only 7 days. Third, seeds dried in the lab, even at relatively moderate temperatures, showed a decline in germination with seed moisture loss. The addition of high temperatures accelerated this decline in germination. We discuss the relevance of heat and desiccation sensitivity of seeds dispersed by bears to successful seed germination in burned and late-seral mesic and xeric chaparral.

Disinfecting traps that have captured small mammals is one recommendation for preventing occurrence of hantavirus infection; however, the potential effects of disinfection on small mammal trappability have not been investigated thoroughly. We conducted an experiment to compare the effects of 2 disinfectants (Lysol® and household bleach) on the trappability of 4 small mammal species (Peromyscus maniculatus, Neotamias spp., and Spermophilus lateralis). We established triplicate trap grids in 2 forest types (red fir and mixed conifer), each consisting of a 6 × 6 array of Sherman live-traps placed at 10-m intervals. Traps were given 1 of 3 treatments: control (water), Lysol, or bleach; the treated traps were placed in an alternating pattern. Traps were open for 4 consecutive nights with daily treatment application. We found a difference in the trappability of Peromyscus between years; however, we did not detect a statistically significant difference in trappability resulting from disinfection for any of the 3 study species. Disinfectant effects on capture probability within Peromyscus were not supported by model selection in Program MARK. Collectively, these results indicate that although populations may fluctuate temporally and spatially, trap disinfection does not have a significant effect on small mammal trappability.

Loss of reproductive productivity in hosts of the Brown-headed Cowbird (Molothrus ater), a nest parasite, may limit the success of conservation and recovery efforts that focus on restoring avian habitat. We investigated the relationships between parasitism frequency of 2 vireos—the endangered Black-capped Vireo (Vireo atricapillus) and the White-eyed Vireo (Vireo griseus)—and characteristics of the neighboring avian assemblage. Our objective was to identify assemblage characteristics that are useful for predicting parasitism frequency We hypothesized that parasitism frequency of the vireos would decrease with increasing alternate host abundance and increase with increasing abundance of cowbirds. All Black-capped Vireo nests (n = 20) and 81% of White-eyed Vireo nests (n = 27) were parasitized. Parasitism frequency of White-eyed Vireos was positively correlated with the number of cowbirds detected (r = 0.84, df = 4, P = 0.018). Parasitism frequency of White-eyed Vireos was negatively correlated with abundance of the Black-and-white Warbler (Mniotilta varia; r = 0.891, df = 4, P = 0.009) but was not correlated with abundance of other cowbird hosts. The relationship between Black-and-white Warbler abundance and parasitism frequency may be due to chance, given the small sample size and narrow range of parasitism frequencies, but the relationship may also reflect an interaction (requiring further investigation) between parasitism and the vegetation characteristics associated with Black-and-white Warblers. Our results imply that reducing cowbird abundance will reduce parasitism frequency of Black-capped Vireos. When the number of cowbirds in an area predicts parasitism, land managers would benefit from identifying a target cowbird abundance based on the levels of parasitism the host population can tolerate while still meeting productivity and population objectives for the species.

Much research has been conducted on the mating systems of poeciliid fish in aquaria; however, there are fewer studies that examine mate sampling of these fish in the wild. In general, male poeciliids are characterized as being unselective in their mate choices and will attempt to copulate with seemingly all available females. Females are selective, copulate infrequently, and are often pursued by “ardent” males who may force copulations. To avoid male harassment, females in aquaria will often shelter from males among other females in shoals. Here, we examined the mate-sampling behaviors of male and female Pecos gambusia Gambusia nobilis by following individuals swimming in an outflow pool of Diamond Y Spring in southwestern Texas. In most cases, a male approached a solitary female, followed her briefly, and then left for no apparent reason. Approaching a number of females increased the likelihood that the male would follow one, and the longer a male followed a female, the more likely he was to copulate with her. As females were larger and faster than males, they could avoid males by swimming away from them. We found no evidence of the persistent males that harass seemingly unreceptive females as seen under aquarium conditions, nor did we see females join a shoal to stop pursuit by males. However, the activity of one male following a female did appear to attract other males who would compete to follow and attempt copulation. This competition might ensure that only superior males gain reproductive opportunities.

Rabbit abundance patterns in the North American Southwest are poorly known, particularly relative to the potentially important influences of rainfall and plant production. We conducted a 10-year study on the comparative densities of black-tailed jackrabbits (Lepus californicus) and desert cottontail rabbits (Sylvilagus audubonii) in relation to annual rainfall and plant production in both black grama (Bouteloua eriopoda) grassland and creosotebush (Larrea tridentata) shrubland habitats in the northern Chihuahuan Desert. We found that both species of rabbits were more abundant in black grama grassland than in creosotebush shrubland and that plant production was positively correlated with rainfall at both habitats. However, rabbit densities were not positively correlated with rainfall or plant production in either habitat. In fact, both species of rabbits exhibited gradual, multiyear changes in abundance rather than the patterns of high annual variation observed in desert rodent communities. Our findings of no significant relationship between plant production and rabbit densities indicate that rabbit abundance in the northern Chihuahuan Desert may not be strongly regulated by short-term, bottom-up effects of annual variation in plant production. Long-term trends indicate that other factors such as disease or predation may be equally or more important. We suggest that future research evaluate both top-down and bottom-up influences to elucidate the temporal dynamics of Chihuahuan Desert rabbit abundance.

American pikas (Ochotona princeps) seem to be especially vulnerable to climate change, with recent extinctions of pika populations being attributed to global warming. Incomplete historical location records are currently used to examine changes in pika distributions. A method of determining recent pika distributions in the absence of historical records is needed. Here I report on changes over time of known-age pika fecal pellets up to 36 years old. Predictable changes in diameter, internal consistency, and color of pellets provide a method to approximate the dates of last occupation in patches where pikas have been extirpated.

I determined the distribution of limpets (Gastropoda: Ancylidae: Ferrissia) in the Colorado River and Rio Grande basins by handpicking specimens from the undersides of rocks and vegetation at 16 sites from a total of 495 surveyed sites in Colorado, Utah, New Mexico, and Arizona. Shell morphology, including morphometries, was compared to species holotype descriptions and museum lots. Ferrissia rivularis occurred in the upper Colorado, Gunnison, and San Juan rivers, and in the upper Rio Grande basin. Ferrissia walkeri, hereafter called the Walker morph, occurred only in the Gila River basin of Arizona and New Mexico. I reviewed the problems of classification of the Walker morph as being either F. walkeri, described from Arkansas and noted in Michigan and Baja California Sur, or Ferrissia fragilis, described from California and noted from the eastern United States. The Walker morph is identified by its vertical trending protoconch, which lies well within the right posterior quadrant, with the apex of the shell within the posterior third, and the anterior edge of the protoconch lying posterior to and below the apex. The importance of the Gila River Ferrissia population is discussed in reference to the often-proposed paleoaquatic fauna route between the eastern United States and California.

Type-conversion of coastal scrub to exotic annual grassland has been extensive in certain parts of southern California, especially in drier inland locales. Field observations suggest that rock outcrops harbor native perennials associated with coastal scrub vegetation after conversion to exotic annual grassland has occurred. Surveys were conducted to test this observation. In addition, measures of fossorial mammal disturbance, soil depth, exotic annual plant abundance, and soil moisture were collected and used to infer potential mechanisms that may influence patterns of native and exotic vegetation. Results showed that larger outcrops are associated with more native perennial species than smaller outcrops, consistent with predictions based on species-area relationships. In addition, the edges of rock outcrops were shown to have greater native perennial species richness than the surrounding exotic annual grassland matrix. Higher soil moisture, lower soil depth, and less disturbance by Botta's pocket gopher (Thomomys bottae) were also found at the edge of rock outcrops compared to the surrounding grassland matrix. Furthermore, soil depth was positively correlated with pocket gopher disturbance and with exotic annual grass cover. Rock outcrops serve as refuge habitat for native coastal scrub perennials in areas where exotic annual grasses have become dominant. Rock outcrops may become increasingly important for conservation efforts if remaining coastal scrub vegetation continues to deteriorate.

Although the aquatic insect fauna of Utah and their associated adult forms are well documented taxonomically and biogeographically, little is known about seasonal and elevational patterns of aquatic insect diversity in individual Wasatch streams. We selected the American Fork River, a relatively pristine stream with little anthropogenic disturbance, as our target stream to investigate elevational distribution and seasonal phenology of adult forms of Ephemeroptera, Plecoptera, and Trichoptera (EPT). From April to October in 2003 through 2005, a total of 71 adult forms of EPT species were documented along the American Fork River. No single sampling period captured more than 30 species, and richness per sampling period averaged 8 species for all sites combined. The mid-elevational site (1862 msl) was the most species rich, with 54 species of transitional fauna captured along the elevational gradient. As such, this site is an important reference for maximum potential richness. Plecoptera emerged earlier in the year than Trichoptera, with the Plecoptera-dominated community being most rich in June, and the Trichoptera-dominated community being most rich in August. We observed 3 distinct seasonal species suites and 3 elevationally zoned community assemblages that were recurrent in their timing and location from year to year. The compiled species lists, life histories, and preliminary investigation of ecological trends provide a firm basis for further systematic studies on the ecology, water quality, and conservation of the aquatic insects of the American Fork River and similar mountain streams, particularly in the Wasatch region.

Phragmites australis (Cav.) Trin. ex Steud. (common reed), already one of the world's most widespread plant species, has realized rapid range expansion in coastal wetlands of North America in the past century, but little is known about P. australis range expansion in inland wetland systems. We used genetic analyses, aerial photographs, field surveys, and a greenhouse experiment to study the extent and mechanism of nonnative P. australis invasion of Utah wetlands. We collected and genetically analyzed 39 herbarium samples across the state and 225 present-day samples from northern Utah's major wetland complexes. All samples collected before 1993 and all samples collected outside the major wetlands of northern Utah, including some as recent as 2001, were identified as native (haplotypes A, B, D, and H). Only 10 (4%) of the present-day samples were native, each from small, discrete, low-density stands; the remaining samples were nonnative (haplotype M). Our earliest nonnative sample was collected near the Great Salt Lake in 1993. Around the Great Salt Lake, which contains 40% of Utah's wetlands, P. australis cover has increased from 20% to 56% over the past 27 years—an increase that appears attributable to the nonnative strain. In a 3-month-long greenhouse experiment, the nonnative haplotype grew taller, had more aboveground biomass, and had a greater above- to belowground biomass ratio than the native haplotypes regardless of nitrogen, phosphorus, or water availability. Nonnative P. australis is rapidly invading the wetlands of northern Utah. Areas in Utah where the native P. australis remains should be identified and protected.

Potamodromous fish are poorly studied even though they are threatened often by human activities. The June sucker (Chasmistes liorus) is an endangered potamodromous species endemic to Utah Lake. Larval June suckers have not been collected from Utah Lake for at least 3 decades. Recruitment appears to be limited by low temperatures and scarce food, resulting in mass starvation of larval June suckers in the stream environment. We compared water temperature, Zooplankton food availability, and small fish abundance in the stream and in 3 habitats along the stream—lake ecotone (dense emergent vegetation, sparse emergent vegetation, and open lake) to test the hypothesis that all 3 factors would reach a maximum in the dense emergent vegetation of the stream—lake ecotone. We used the abundance of fathead minnows in each habitat type as a surrogate for small fish like juvenile June suckers. We found that temperature, food, and fathead minnows reached their maximums in the open lake rather than in vegetated habitats of the streamlake ecotone. The stream had the lowest average temperatures (15.1 °C) and the lowest Zooplankton concentrations (61 · L^-1) over the growing season. Contrary to expectations, low temperatures (16.9 °C) and low food abundance (505 · L^-1) also characterized the densely vegetated habitat, whereas the open lake had the highest temperatures (20.4° C) and highest concentrations of Zooplankton (2353 · L^-1). Restoration should include a mechanism to transport larval fish through the densely vegetated portion of the stream—lake ecotone, which can be hundreds of meters wide, to the warm productive waters of the open lake. The braided planform of the terminal reaches of Hobble Creek should be replaced with shallow riffles to increase mean stream velocity and decrease the transport time of larval June suckers.

We report the discovery in Utah of Dipodomys spectabilis, a species previously unknown to occur in the state. We searched for D. spectabilis in extreme southeastern Utah, south of the San Juan River, and were successful in finding mounds and burrows characteristic of the species and in capturing one individual. This is the northernmost record for D. spectabilis and extends its known range ∼84 km northwest of the nearest previously reported locality (Fruitland, San Juan County, New Mexico). A flea, Meringis rectus, collected from D. spectabilis, is also the first record of its species in Utah.

The parasitic wasp Mymaromella pala Huber and Gibson (Hymenoptera: Mymarommatidae) was collected at 4 sites within a canyon reach of the Kootenai River in Lincoln County, Montana. This minute species has only recently been described, but it appears to have a large distribution throughout the United States and to be associated with upland and riparian forests.

Antipredatory defense of pronghorn (Antilocapra americana) neonates (≤1 month old) by adult females (>18 months old) is well documented throughout the geographic range of this species. However, reports of male pronghorn defending neonates against predators are limited to a single study in northwestern Wyoming where occurrences were documented of adult males assisting female pronghorn in defending neonates against coyotes (Canis latrans). To our knowledge, defense of neonatal pronghorn by yearling males (12–18 months old) has not been reported previously for this species. We report occurrences of antipredatory defense of neonatal pronghorn by yearling males in southwestern South Dakota.

The skeleton of a young American black bear (Ursus americanus) possessing asymmetrical distortions of the 5 caudalmost lumbar neural spines was recovered from west Texas. We attribute this abnormality, presumed to be congenital, to the absence or atrophy of the right multifidus muscle straddling L3 and to the series of compensatory muscle adjustments required to maintain spinal alignment. This finding may have important management implications for black bears in Texas, given the possibility that our specimen originates from a partially isolated population.