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Interspecies interactions can affect how species are distributed, put constraints on habitat expansion, and reduce the fundamental niche of the affected species. Using logistic regression, we analyzed and compared 174 Tamias palmeri and 94 Tamias panamintinus within an isolated mountain range of the Basin and Range Province of southern Nevada. Tamias panamintinus was more likely to use pinyon/ponderosa/fir mixed forests than pinyon alone, compared to random sites. In the presence of T palmeri, however, interaction analyses indicated T. panamintinus was less likely to occupy the mixed forests and more likely near large rocks on southern aspects. This specie s-by-habitat interaction data suggest that T. palmeri excludes T panamintinus from areas of potentially suitable habitat. Climate change may adversely affect species of restricted distribution. Habitat isolation and species interactions in this region may thus increase survival risks as climate temperatures rise.
Most alpine glaciers worldwide are receding rapidly, revealing new streams to be colonized by aquatic organisms. Several major questions are whether these new streams are colonized by aquatic organisms, how fast this colonizing occurs, which organisms are colonizing, and what factors constrain dispersal. We examined longitudinal patterns (over a length of 5 km) in physicochemistry, as well as periphyton and macroinvertebrate composition in 2 glacier streams (Dinwoody, Gannett) in the Wind River Range wilderness, home to the few remaining glaciers in the contiguous USA. We found that newly emerged streams near the glacial snout were inhabited by periphyton and macroinvertebrates, suggesting rapid colonization by biota. Longitudinal (distance from the glacier) patterns were documented in water temperature (increasing), particulate organic carbon (decreasing), particulate phosphorus (decreasing), and benthic organic matter (increasing in Dinwoody). Macroinvertebrate total density and operational taxonomic units (OTUs) also increased with distance from the glacier. Chironomids (Diamesinae) dominated the macroinvertebrate assemblages, a result supporting the importance of water temperature as a controlling factor influencing macroinvertebrate s. Sixteen OTUs were documented, with low-elevation mayflies, stoneflies, and caddisflies occurring at sites with warmer temperatures (>3.0 °C). Only Diamesinae were found at sites nearest the glacial source where water temperature was <2.0 °C As glaciers recede, the physicochemistry of alpine streams will change and likely differ among glacial streams. The mechanistic basis for the consequent effects of these physicochemical changes on freshwater biodiversity is still poorly understood.
Pleurocladia lacustris A. Braun is a freshwater member of the Phaeophyceae, a class of algae that occurs almost entirely in marine waters. It has previously been reported from only about 13 freshwater locations worldwide, just 2 of which are in North America. Outside of North America, P. lacustris has been listed as a threatened species on several European red lists. In this paper, we report the discovery of P. lacustris in 3 calcareous streams draining the Santa Lucia Mountains in coastal California, sites that are more than 1200 km from the nearest known population. Pleurocladia lacustris is a filamentous, benthic species that forms distinctive hemispherical colonies. It co-occurs with the green alga Cladophora glomerata and species of cyanobacteria (Rivularia, Nostoc, Schizothrix spp.). Detailed color illustrations of the diagnostic macroscopic and microscopic features are provided and appear identical to those features of European populations. In the California streams, P. lacustris and other associated algae co-precipitate CaCO3 to form carbonate crusts on rocks. Preliminary ecological data are consistent with other streams and lakes in Europe where P. lacustris has also been reported (pH > 8.0, calcareous substrata, travertine). The global distribution of this presumed rare alga is also described and examined with respect to a specialized ecological niche.
Most of the native shrubsteppe habitat in the northern Columbia Basin of eastern Washington has been invaded by cheatgrass (Bromus tectorum) or converted to agricultural lands. Therefore, ecological patterns and dynamics on native shrubsteppe and reestablished grasslands are of high conservation interest. We analyzed the cheek pouch contents of Great Basin pocket mice (Perognathus parvus) from 48 study sites in this region to quantify seed collection by this species and to determine the influence of habitat type on cheek pouch seed contents. In all 3 habitat types-newly established Conservation Reserve Program (CRP) lands, older CRP lands, and shrubsteppe-B. tectorum constituted the majority of seeds collected from the cheek pouches. Mean generic richness of collected seeds was higher in shrubsteppe than in new CRP habitats. On average, females collected a greater number of seed genera than males did, and pocket mice collected more seed genera as the autumn season progressed. Exotic B. tectorum has become the most frequently collected autumn food resource for pocket mice in the northern Columbia Basin.
American bison (Bison bison L.) preferentially use black-tailed prairie dog (Cynomys ludovicianus L.) colonies over uncolonized range in the mixed-grass prairie of North America. To assess bison use of prairie dog colonies in a different ecosystem, the shortgrass steppe, this study was conducted at the Vermejo Park Ranch, New Mexico. Driving surveys were conducted in summer 2007 to determine the number of bison on and off prairie dog colonies in 2 pastures. Prairie dogs occupied 25.5% and 48.5% of the 2 pastures surveyed. Bison of both sexes used prairie dog colonies more than expected compared to a scenario of bison using colonies based on colony availability (P < 0.001). With the exception of bulls in one pasture, bison observed off-colony were more likely to be grazing than bison observed oncolony (P < 0.04). When selection of prairie dog colonies was assessed for only those bison observed grazing, bulls in both pastures and cows in one pasture used prairie dog colonies more than expected based on availability (P ≤ 0.001). Forage quality was superior on prairie dog colonies, with crude protein higher (P < 0.001) and acid detergent fiber lower (P < 0.001) in blue grama (Bouteloua gracilis [Willd. ex Kunth] Lag. ex Griffiths) collected on-colony than offcolony. Further studies under a variety of conditions are still needed, but selection for prairie dog colonies by bison at Vermejo, combined with findings from previous studies, suggests that during the growing season, bison and cattle (Bos taurus L.) might select prairie dog colonies over uncolonized range in both the northern and southern extents of North American grasslands.
Population declines of Greater Sage-Grouse (Centrocercus urophasianus) throughout the western United States have been attributed to the loss, degradation, and fragmentation of sagebrush (Artemisia spp.) habitats. Increased energy development may further fragment sagebrush habitat, isolating sage-grouse populations and resulting in genetic drift, inbreeding, local extinction, or rapid divergence. We conducted a genetic survey of 3 remote sagegrouse populations in northeastern Utah to assess mitochondrial diversity relative to other portions of the species' range. We did not detect any unusual haplotype compositions in these populations. However, haplotype composition of the Anthro Mountain and Strawberry Valley reference populations differed from haplotype compositions of other northeastern Utah populations. These populations are spatially separated by Desolation Canyon of the Green River. This canyon may constitute a geographic barrier to gene flow in this area, given low population densities and reduced dispersal potentials. This potential barrier will be an important consideration in future conservation efforts such as translocations. The halotype composition of the Anthro Mountain and Strawberry Valley reference populations may be altered by translocations subsequent to our sampling effort. The effect of these translocations on the reference halotypes and population vital rates is currently under study.
Investigation of amphibian occupancy at potential breeding sites can provide information about the distribution and relative abundance of species, as well as insights into habitat relationships across large areas such as national parks. Based on previous research in the Greater Yellowstone Ecosystem (GYE), we hypothesized that the probability of amphibian occupancy increases with water conductivity. We conducted amphibian surveys with habitat measurements at 235 wetland sites in the GYE in 2002, thereby locating breeding populations of boreal toads (Anaxyrus boreas), boreal chorus frogs (Pseudacris maculata), Columbia spotted frogs (Lithobates luteiventris), and barred tiger salamanders (Ambystoma mavortium). Repeat surveys provided detection probabilities, which allowed for unbiased estimates of occupancy. The boreal chorus frog was the most common amphibian in the GYE, with breeding populations occupying approximately 48% of the sites, followed by Columbia spotted frog (35%), barred tiger salamander (14%), and boreal toad (13%). Occupancy corrected for detection probability averaged 36% higher (range 27%–50%) than naive estimates of occupancy. Detection rates ranged from 0.65 to 0.78 for the 4 species. Modeling of habitat covariates indicated that higher conductivity was positively associated with toad occupancy but negatively associated with chorus frog occupancy; Columbia spotted frog and barred tiger salamander occupancy was little influenced by water conductivity. Fish presence had a negative effect on occupancy of barred tiger salamanders and boreal chorus frogs. These results may help managers in the GYE manage and conserve important breeding habitat for amphibians, particularly if longterm monitoring efforts indicate declines in amphibian populations.
Palmer's chipmunk (Neotamias palmeri) is a medium-sized chipmunk whose range is limited to the higherelevation areas of the Spring Mountain Range, Nevada. A second chipmunk species, the Panamint chipmunk (Neotamias panamintinus), is more broadly distributed and lives in lower-elevation, primarily pinyon-juniper (Pinus monophylla-Juniperus osteosperma) habitat types. Panamint chipmunks are not closely related to Palmer's, but field identification of the 2 species is unreliable. Palmer's chipmunk is a species of concern in the state of Nevada and is listed by the International Union for Conservation of Nature (IUCN) as endangered. As such, conservation of Palmer's chipmunks is a priority in the Spring Mountains National Recreation Area. We sampled putative Palmer's chipmunks from 13 sites distributed across the Spring Mountains during 2010–2011. We removed Panamint chipmunks by using DNA-based identifications and then analyzed the genetic population structure of Palmer's chipmunks by using a panel of 9 microsatellites. Of the 228 samples that were genotyped, 186 were Palmer's; there was no evidence of hybridization between species. Four sites had exclusively Panamint chipmunks, 5 had exclusively Palmer's chipmunks, and 3 had a mixture of the 2 species. In this study, Palmer's chipmunks were exclusively captured at sites above 2400 m elevation, and Panamint chipmunks were exclusively captured at sites below 2200 m. Panamint chipmunks were trapped in areas typed as pinyon-juniper, but they were also trapped at sites typed as ponderosa pine (Pinus ponderosa) and mixed conifer. Both species were trapped at 3 sites; at all 3 sites, the lowerelevation traps contained Panamint chipmunks and the higher ones Palmer's chipmunks. Population structure within Palmer's chipmunks was minimal: heterozygosity was relatively high, and the populations displayed no signs of recent bottlenecks. Indications are that the distribution of Palmer's chipmunk is limited to higher-elevation areas in the Spring Mountains, but within this area, Palmer's chipmunk occurs as a single, large, well-connected, and stable population.
Sonic transmitters were affixed to 10 large (40.4–51.4 cm TL) adult bonytail Gila elegans in 2003 from Cibola High Levee Pond, a small, isolated backwater adjacent to the lower Colorado River in Arizona and California, Point and paired directional observations showed that all marked adult bonytail occupied interstices of large riprap during daytime and used open water areas during darkness, presumably to feed. There were 2 spatial patterns of nighttime distribution by adult fish; 70% of fish exhibited mesohabitat site fidelity to a particular area of the pond, while others appeared to move about at random. Selection or design of bonytail management areas including grow-out and refuge sites should consider cover requirements for larger fish, as this may be a limiting factor if lack of cover subjects some individuals to higher predation risk.
We assessed the current distributions for 2 subspecies of the brush rabbit, Sylvilagus bachmani peninsularis and S. b. exiguus, on the Baja California Peninsula, Mexico. On the basis of field sampling, field notes, and voucher specimens in scientific collections, we demonstrated that (1) both subspecies have been previously recorded in mesic habitats with conditions associated with oases and streams; (2) the 2 subspecies exhibit disjunction in their distributions in the middle and southern portions of the peninsula; (3) habitats are threatened by human activities and desertification, which explains why brush rabbit populations are currently fragmented; and (4) specimens of S. bachmani have not been collected or observed in the last 20 years, with effort concentrated mainly in the southernmost part of the peninsula (San Lucas faunal district). We suggest that S. b. exiguus be considered threatened, requiring immediate conservation actions, including habitat preservation; and we suggest that the southern form, S. b. peninsularis, be considered extinct due to anthropogenic activities.
The desert spring ecosystem of the Cuatro Ciénegas basin, Mexico, hosts an extraordinary but increasingly imperiled assemblage of native and endemic aquatic organisms. Among the more vulnerable to extinction is the microendemic Cuatro Ciénegas platyfish Xiphophorus gordoni, which is at particular risk due to its highly restricted distribution and small population size. Given the growing demands on water resources in this arid region, we conducted a survey of mitochondrial DNA sequence variation in the cytochrome b gene to establish a baseline for long-term genetic monitoring of this endangered species. Fifty-eight specimens were collected from the 2 subpopulations known to persist, Laguna Santa Tecla (27) and Teclitas (31). Three haplotypes were observed across all samples, with 3 and 2 haplotypes observed at Laguna Santa Tecla and Teclitas, respectively. Sequence divergence ranged from 0.02% to 0.03% among variants and averaged 0.317 differences between populations. Haplotype and nucleotide diversities were moderately low in Laguna Santa Tecla (0.467 and 0.0008, respectively) and severely low in Teclitas (0.065 and 0.0001, respectively). Exact tests revealed significant heterogeneity in haplotype distributions between sites (P = 0.006), as did the pairwise estimate of ΦST (0.135; P = 0.005). Tests of deviation from neutrality were nonsignificant. Microendemism of X. gordoni and marginal substitution differences between the few extant haplotypes suggest that low genetic variation is a historical characteristic of this species; however, population declines associated with recent habitat loss have likely further compromised standing levels of genetic variation. Development of a long-term population and genetic monitoring program that incorporates multilocus nuclear DNA markers is advised and should be tied to a more thorough characterization of the basic biology and life history of this species, establishment of captive or refuge populations, and further improvement of habitat.
Surveys were performed to examine the diversity of Ephemeroptera and Plecoptera in selected lakes in Glacier National Park, Montana, and to generate data for use by the National Park Service. Shallow shoreline sites were sampled by disturbing the bottom and examining the substratum. Published records and previously collected reference specimens were examined. Data were obtained from a total of 29 lakes, but 3 yielded no mayflies or stoneflies. Twelve genera and 21 species of Ephemeroptera, and 11 genera and 5 species of Plecoptera, were found. Most lakes sampled had a diverse fauna of both orders.
The recently described Oreoleptis torrenticola Zloty, Sinclair and Pritchard (Diptera: Tabanomorpha), belonging to the monotypic family Oreoleptidae, was previously described from the Northern Rocky Mountains of the USA and Canada. However, as part of a broad, multidisciplinary study by the Yakama Nation, 30 larvae of O. torrenticola were collected at multiple sites within the Twisp River of the Cascade Mountains in Okanogan County, Washington, 2008–2010. This finding represents a substantial range extension for the species.
The gray fox (Urocyon cinereoargenteus) is an under-studied species in North America. Here we provide data gathered through observations over 17 d at a gray fox den in San Mateo County, California. We recorded prey indices through direct observation, as well as through indirect observation with photos recorded by motion-triggered cameras. The largest prey was a mule deer fawn, which we determined was killed by a gray fox. This finding is the first record of gray fox predation on mule deer. Lagomorphs and rodents formed the majority of prey items. We also recorded behavior that both contradicted and corroborated previous literature. We observed the male bringing food items to the den, a behavior that previous researchers have disagreed about. We also observed allogrooming between the adult pair, as well as one instance among pups where leg-lifting accompanied by presentation of the genitalia was clearly used as an aggressive dominant behavior rather than a submissive behavior, as reported in previous literature.
During research on brook trout (Salvelinus fontinalis [Mitchill]), we collected larval and pupal specimens of the midge Odontomesa fulva (Kieffer) (Diptera: Chironomidae) from Pine Cree Creek, in the Cypress Hills area of the Northern Great Plains of Saskatchewan, Canada. This record is the first observation of O. fulva from the province. The larvae of the population of O. fulva in this study prefer shallow pools in this first-order, cold water stream. The species displays a univoltine emergence phenology. This range extension of O. fulva highlights and reinforces the importance of the Cypress Hills to the unique aquatic faunal biodiversity and ecology of Saskatchewan and the Northern Great Plains.
Capturing Common Ravens (Corvus corax) is very difficult. Several methods are currently used, but none effectively catch large numbers (>25 birds) of ravens at one time. Efficient capture of large numbers of ravens is needed for some autecology studies. We describe and evaluate the effectiveness of using a prebaited rocket net trapping method for simultaneously capturing large numbers of ravens. The study sites were within 2 landfills in California's Mojave Desert, one at Edwards Air Force Base and the other at Fort Irwin National Training Center. We captured 283 ravens on 5 trapping occasions between 1995 and 1997, with an average of 57 birds per trapping occasion. We observed greater numbers of ravens at the bait sites with increasing bait duration, and these numbers appeared to level off after 25 to 30 days of baiting. Longer bait durations may habituate ravens to the resource and compensate for their wariness, which could increase capture success. More than half of the ravens captured (55%) were adults, and subadults composed the remaining age class (42%). Only 3% of the ravens captured were hatch-year birds, a result of trapping early in the breeding season. Using rocket nets is a safe and effective method to capture large numbers of ravens.
Males of solitary wasp species are faced with the task of locating potential mates, a task made more difficult by inconspicuous females and a landscape seemingly devoid of landmarks. Males may employ a variety of strategies to locate females. In this study, we test for variation among males within the sun dance of Bembix. We show that males of Bembix americana spinolae Lepeletier behave differently within the sun dance and that these differences can be predicted by the size of the male. We show that large males spend more time at “rest” and require a greater number of male-male contacts to be displaced from rest than small males. This difference in mate location strategy, however, appears to be density dependent, as large and small males in small aggregations exhibit no difference in the strategies they employ.