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The Mohave ground squirrel (Xerospermophilus mohavensis) is endemic to the western Mojave Desert of California. It is listed as threatened under the California Endangered Species Act, yet there is little published information on its habitat requirements. We studied the diet of Mohave ground squirrels at 4 sites in desert scrub habitat in Inyo County, California, primarily by microhistological analysis of 754 samples of fecal pellets collected from live-trapped animals. Over all sites and seasons, shrub foliage was the largest component of the diet (39.8% relative density) and mainly derived from several taxa of Chenopodiaceae: winterfat (Krascheninnikovia lanata), spiny hopsage (Grayia spinosa), and saltbushes (Atriplex spp.). Forb leaves were next in importance (34.1% relative density), especially from Fabaceae (Astragalus and Lupinus), Polemoniaceae (Gilia and Linanthus), and Asteraceae. Flowers, pollen, and seeds were also major components (20.3% relative density). Leaves composed nearly all of the diet in spring, whereas pollen, flowers, and seeds made up about a third of the diet in summer. Following dry winters when annual forbs were limited, Mohave ground squirrels depended primarily on foliage from perennial shrubs and forbs. Following wet winters when spring annuals were abundant and most plant species flowered and set seed prolifically, squirrels consumed a high proportion of leaves plus flowers, pollen, and seeds of annual forbs. Mohave ground squirrels reproduced only after winter rainfall >80 mm that resulted in a standing crop of herbaceous annuals ≥100 kg · ha-1. Mohave ground squirrels consumed very little of the nonnative annual plant biomass present on our study sites (Erodium, Salsola, Bromus, and Schismus contributed <3% overall to the diet). Conservation implications include the following: (1) priority should be given to protecting habitats supporting preferred perennial forage plants, including winterfat and spiny hopsage; (2) habitats with an understory dominated by native annual forbs have higher value than those dominated by nonnative plants, especially annual grasses; and (3) if climate change results in lower and less regular winter precipitation, suitable habitat for Mohave ground squirrels may be reduced and fragmented in the drier portions of the geographic range.
New host records are reported for Campiglossa snowi (Hering), Tephritis leavittensis Blanc, and Trupanea nigricornis (Coquillett) on Arnica chamissonis Less. and C. snowi on Arnica mollis Hook. Campiglossa snowi was the only fruit fly reared from A. chamissonis from 3 different populations from the Kenai Peninsula, Alaska, over 5 sample years. A total of 1114 specimens of C. snowi were reared from the flower heads of 337 plants averaging 5 flower heads per plant. Seed damage from fly larvae ranged from 0% to 54.8% per capitulum, with an overall average of 18.3% across all years and between 3 sites on the Kenai Peninsula. Infestation rates for individual capitula and entire plants averaged 56.4% and 79.0%, respectively, across all years and sites. Fly abundance was not consistent from year to year, but peaked during 2010, with substantially lower values in years preceding and following the peak. Campiglossa snowi individuals reared from flower heads at additional sites and across multiple states expand the species' known distribution range.
Trait-based approaches to vegetation analyses are becoming more prevalent in studies of riparian vegetation dynamics, including responses to flow regulation, groundwater pumping, and climate change. These analyses require species trait data compiled from the literature and floras or original field measurements. Gathering such data makes trait-based research time intensive at best and impracticable in some cases. To support trait-based analysis of vegetation along the Colorado River through Grand Canyon, a data set of 20 biological traits and ecological affinities for 179 species occurring in that study area was compiled. This diverse flora shares species with many riparian areas in the western USA and includes species that occur across a wide moisture gradient. Data were compiled from published scientific papers, unpublished reports, plant fact sheets, existing trait databases, regional floras, and plant guides. Data for ordinal environmental tolerances were more readily available than were quantitative traits. More publicly available data are needed for traits of both common and rare southwestern U.S. plant species to facilitate comprehensive, traitbased research. The trait data set is free to use and can be downloaded from ScienceBase: https://www.sciencebase.gov/catalog/item/58af41dee4b01ccd54f9f2ff and https://dx.doi.org/10.5066/F7QV3JN1
Peregrine Falcon numbers in much of the Intermountain West rebounded after a decline during the 1950s, 1960s, and early 1970s. However, recent literature regarding the species suggested that little, if any, growth was occurring in populous north central Utah, which once supported a robust Peregrine Falcon population. A concerted reintroduction effort during the 1980s resulted in establishment of nesting pairs of Peregrine Falcons on artificial towers where they were originally released as nestlings, but traditional nesting cliffs generally remained vacant. More recently, numerous Peregrine Falcon pairs have been observed nesting on cliffs both within and adjacent to their historical range in the region. I combined results from recent literature with numbers gleaned during this study to find that 45 Peregrine Falcon nesting territories are documented for the recovery era in north central Utah.
Southwestern dwarf mistletoe (Arceuthobium vaginatum subsp. cryptopodum) parasitizes ponderosa pine (Pinus ponderosa). It can kill severely infected trees and induce the growth of dense masses of branches that can affect foraging and nesting habitat for wildlife. We tested the hypothesis that higher densities of breeding birds would be correlated with higher levels of southwestern dwarf mistletoe in ponderosa pine forests of Arizona. We estimated densities of 15 species of breeding birds and measured 26 habitat elements in 19 stands. Average dwarf mistletoe ratings (DMR) ranged from 0.0 (uninfested) to 3.7 (severely infested). Although we observed higher densities with higher infestation of dwarf mistletoe for 2 bird species and lower densities for 3 bird species, the effect of dwarf mistletoe on these was minor. Instead, higher snag density, an indirect measure of past mistletoe infestation, was a more important predictor of bird density. With greater snag size or density, the species richness and densities of 3 bird species increased. Because dwarf mistletoe infection can create snags, retaining groups of dwarf mistletoe-infected trees in ponderosa pine stands will provide a continued source of snags, which are important habitat for many wildlife species.
Lake Powell (Colorado River drainage, Utah and Arizona, USA) is an important and unique fishery comprising several nonnative fishes. There are no previous studies of the parasites of the fishes of Lake Powell. We provide a general survey of the metazoan parasites found in the numerically dominant fish species of the reservoir. We collected and surveyed for parasites in 236 fishes of 8 species. We found 832 parasites comprising 13 species. All of the parasite species we found are widespread throughout North America and other parts of the world. Six of the 13 species of parasites we found have been documented previously in the Colorado River system. In general, benthic-feeding fishes exhibited higher parasite richness and intensity compared to pelagic-feeding fishes. This study serves as a baseline for parasite community studies in Lake Powell and can provide a comparison for future studies.
The Threatened plant Spalding's catchfly (Silene spaldingii S.Watson) is known to exhibit prolonged dormancy in which individuals survive belowground for one or more years; detection of all aboveground plants is essential for accurate estimates of prolonged dormancy. We conducted 2 long-term demographic studies of Spalding's catchfly in west central Idaho (2002–2013), following 947 plants in permanent plots for 10 consecutive years. To detect all plants emerging aboveground, we monitored twice each growing season—soon after emergence and at flowering—and searched closely for small, inconspicuous stages. Demographic estimates were based on stage-based transition matrix and mark—recapture analyses. Over 99% of aboveground plants were present and detectable at early monitoring; approximately one-third were rosette plants, most of which represented established plants present in previous years. Annual dormancy was approximately 10%. Detectability declined considerably by flowering (time dependent) and affected the small, ephemeral rosette stage disproportionately (stage dependent). At flowering, 48% of the plants present aboveground early in the season disappeared or became undetectable or unidentifiable. If we had monitored only at flowering time, we would have considerably underestimated population size, overestimated dormancy, and missed most recruitments. Early monitoring was critical for detecting all aboveground plants, obtaining unbiased demographic estimates, identifying a major vegetative stage class, demonstrating retrogression from larger stemmed to smaller rosette plants, and identifying rodents as a major threat. Our results have implications for other plants with inconspicuous, ephemeral, or dormant stage classes and those with long growing seasons in harsh environments where detectability of aboveground plant tissue may decrease over the growing season.
Human activity may mimic predation risks for wildlife by causing abandonment of foraging sites and increasing expenditure of energy. Animals that can tolerate nonlethal disturbance may minimize these fitness costs. We examine this aspect of the risk—disturbance hypothesis by first analyzing recent habitat use of desert bighorn sheep relative to areas of attraction and disturbance. We then compare and contrast sheep responses to differing levels of anthropogenic disturbance between 2 time periods, 30 years apart. Desert bighorn sheep were tolerant of suburban activity when a consistent forage resource (municipal grass) was provided. Males were more tolerant than females, and females returned to natural, steep areas during the birthing season. Increased recreation activity, specifically mountain bike use, may have resulted in avoidance by sheep of otherwise suitable habitat that had been occupied decades earlier, thereby reducing availability of limited habitat. Tolerance increased only when attractiveness was relatively high and decreased as perceived fitness decreased, supporting risk—disturbance theory.
American black bears (Ursus americanus) are opportunistic omnivores with diets that vary seasonally and geographically depending on food availability. Previous scat analyses across several populations suggest that the majority of animal material in the diet of black bears is from insects (mainly ants and wasps). In 2015, a black bear in Yosemite National Park was observed eating dragonflies, a previously unidentified insect food item. Emerging aquatic insects may be an important but overlooked aspect of black bear diet. Documenting the food sources of organisms is critical to understanding their natural history and ecology. In the case of highly digestible food items, visual observation is an important and underrepresented tactic for documenting diet.
Following recent elk (Cervus canadensis nelsoni) population declines in South Dakota, we evaluated space use of elk in response to biotic and abiotic covariates at a regional scale. We built Brownian bridge movement models to examine summer (parturition date to 31 October) and winter (1 November to following year's parturition date) seasonal movements of radio-collared female elk from 2011 to 2013 at 99% home range and 50% core area contour levels. Our primary objective was to evaluate seasonal movements of female elk in response to drought, vegetation resources, and road density. Higher road densities and increased amounts of open-canopied vegetation were correlated with an increase in core area size. Elk inhabiting open-canopied areas may increase their movements in an attempt to find cover and avoid disturbance factors associated with roads. The high levels of human visitor activity in the Black Hills and accompanying disturbance of wildlife highlight the importance of management strategies that consider elk security cover, or lack of cover in open-canopied areas, when devising road management strategies.
In this paper, we provide the first documented evidence of Pinus longaeva from the Tushar Mountain range in central Utah. The P. longaeva trees, initially noticed at the end of September, and further surveyed during the first week of October 2016 are present on 6 small sites on the north-facing slopes of the North Fork of North Creek in the Tushar Mountains of the Fishlake National Forest. We estimate that there are currently up to 179 live individuals that range in age from seedlings to approximately 1400 years. Our data indicate these are particularly slow-growing specimens on very steep sites, in soil of igneous origin. Though many of the trees are infested with dwarf mistletoe, there is little indication that the population is currently at risk from fire, bark beetle attack, or many other common pathogens characteristic of other Pinus species. Nonetheless, there may be reasons for concern associated with future changes to the climate of southern Utah, as well as the impact of invasive species such as white pine blister rust (Cronartium ribicola). We see opportunities for additional research on this unique population and its associated plant community. We also see the need for management strategies to conserve these P. longaeva stands, as well as a possible need to preserve its seeds and/or other genetic materials.
The Kitimat Liquefied Natural Gas (KLNG) Plant is proposed for construction adjacent to Bish Creek (Kitimat, British Columbia, Canada). Bish Creek is a corridor for brown bears (Ursus arctos), and 8 camera traps were deployed along the creek for 1442 trapping days in 2014 to determine baseline activity of brown bears. Brown bear activity varied across weeks, peaking particularly in July and September. Within a 24-h day, bears were commonly photographed during hours 5, 6, and 21 and uncommonly photographed during the 3 hours preceding noon and a 4-h period in the afternoon. However, the time of day that bears were photographed varied across seasons; bears were more commonly photographed during the day in July and at night in September. Understanding this change in activity across seasons will inform management of bear resources and human activities on-site to avoid human—bear interactions.
Camera traps documented 2 solitary American badgers (Taxidea taxus) independently caching juvenile domestic cow (Bos taurus) carcasses during late winter 2016 in the Great Basin Desert of Utah. One carcass was partially buried and the other was entirely buried. Both badgers constructed dens alongside their cache, where they slept, fed, and spent up to 11 days continuously underground. They abandoned the sites 41 and 52 days after initial discovery. While badgers are known to scavenge and to cache small food items underground, this is the first evidence of an American badger caching an animal carcass larger than itself.
Two species of endangered, primarily lake-dwelling sucker are endemic to the Upper Klamath Basin in southern Oregon: shortnose sucker (Chasmistes brevirostris) and Lost River sucker (Deltistes luxatus). A third unlisted species, Klamath largescale sucker (Catostomus snyderi), also occurs in the basin. Apart from a small group of adult Lost River suckers documented in a tributary to Upper Klamath Lake in the late 1990s, it is generally believed that though the listed sucker species spawn in tributaries, the larvae out-migrate within days of swim-up, and therefore, there is no juvenile residence in the tributaries. We used X-ray imaging and vertebral counts to identify 347 juvenile suckers collected from tributaries to Upper Klamath Lake between 2006 and 2008. We positively identified 13 individuals as Lost River sucker. Our finding of juvenile endangered suckers rearing in tributaries to Upper Klamath Lake challenges the previous finding that larval and juvenile suckers only spend a small portion of their lives in rivers. This finding may have broader implications for future research and management of endangered suckers in the Klamath Basin.