Registered users receive a variety of benefits including the ability to customize email alerts, create favorite journals list, and save searches.
Please note that a BioOne web account does not automatically grant access to full-text content. An institutional or society member subscription is required to view non-Open Access content.
Contact email@example.com with any questions.
Lake Abert, a terminal alkaline salt lake in south central Oregon, has been a key staging area for migratory waterbirds along the Pacific Flyway. In 2014, the lake shrank to about 5% of its maximum size, and its salinity increased from 75 g • L-1 to 250 g • L-1. This resulted in a major ecosystem shift from one dominated at higher trophic levels by invertebrates and waterbirds to one composed primarily of hypersaline-adapted microbes. A large variety of halophilic bacteria and archaea were also detected using 16S rRNA metagenomic sequence analysis. The loss of prey and staging habitat for migratory waterbirds was especially pronounced for Eared Grebe, Red-necked Phalarope, and Wilson's Phalarope, all of which feed on brine shrimp and alkali flies. The last time the lake was in this state was nearly a century ago during the Dust Bowl of the 1930s, which was a once-in-500-years drought. To understand the causes of the current event, we examined hydrological, climatic, and biological data. The primary cause of the event appears to have been the combined effects of upstream water diversions and lower river flows that were exacerbated by a moderate decade-long drought and elevated evaporation rates.
Food availability is one of the most important factors influencing reproduction in mammals. Reproductive success of some species can be negatively affected when body reserves are depleted during long periods of adverse weather conditions. We investigated the relationship of forage availability and weather variables on reproduction by black-tailed prairie dogs (Cynomys ludovicianus) and the effects of black-tailed prairie dog reproduction on reproduction by black-footed ferrets (Mustela nigripes), a prairie dog specialist predator. Prairie dogs draw on stored energy reserves to support reproduction (i.e., capital breeding), while ferrets likely rely on availability of prey during the reproductive period (i.e., income breeding). We expected that productivity of prairie dogs would positively correlate with precipitation during the previous summer and availability of spring forage and that harsh winter conditions would negatively affect reproduction. We also expected that productivity of ferrets would be positively correlated with productivity of prairie dogs because of the net increase in available prey during the ferret's litter-rearing season and because female ferrets might selectively prey on juvenile prairie dogs. At 2 sites in South Dakota during 2008–2010, reproduction by prairie dogs was most strongly influenced by precipitation received during the previous year and especially by winter severity. Harsh winter conditions resulted in a marked decline in reproduction during 2010. Although reproduction by ferrets varied little across years of our study, the success of long-term conservation and reintroduction strategies for the endangered black-footed ferret could be influenced by climate-driven changes in prairie dog reproduction.
Fine-scale genetic structure in animal populations can have important consequences for evolutionary processes and can influence conservation and management decisions. Cervids often live in matrilineal social groups, and this spatial grouping can create fine-scale genetic structure among females. We used DNA and radio-location data at Fort Carson Military Reservation in south central Colorado, USA, to determine whether female mule deer (Odocoileus hemionus) living in close proximity were more likely to be related. Spatial data were obtained over an 18-month period using data transmitted from GPS collars. Average positions for each animal were correlated with relatedness estimates calculated using 7 microsatellite loci. We found significant spatial autocorrelation for females at distances ≤1000 m, which suggests that females were frequently philopatric. In addition, females appeared to occasionally disperse over relatively longer distances, as we found evidence of related females separated by distances up to 28,000 m. Fine-scale genetic structure may have important implications for managing chronic wasting disease, which is relatively common at this site.
Human activities have extensively altered native fish assemblages and their habitats in the western United States. Conservation and restoration for long-term persistence of these fishes requires knowledge of their distributional patterns and life history requirements. Northern leatherside chub Lepidomeda copei (hereafter northern leatherside) is a cyprinid native to the Snake and Bear River Basins of Wyoming, Idaho, Nevada, and Utah, and it is believed to have declined in distribution relative to historical records. To address information gaps in the species' ecology and assess its status in the state, the objectives of this study were first to document the distribution (2010–2011) of northern leatherside in Wyoming and then to examine habitat factors related to the entire fish assemblage and to evaluate specific habitat associations of northern leatherside in the Bear River Basin, Wyoming. In the Bear River and Upper Snake River Basins, we documented the distribution of northern leatherside and compared it to the previously known distribution. Across the Bear River Basin, we used habitat measurements to assess abiotic features related to the distribution and abundance of northern leatherside. Northern leatherside was found across the Bear River Basin and was present in 2 streams each in the Upper Snake River and Green River Basins in Wyoming. Populations in Wyoming appear to represent the core of northern leatherside range, and our work provided a finer-scale delineation of the species' occurrence. Northern leatherside was collected from a variety of habitats, but multivariate analyses and occurrence modeling indicated it was associated with increased channel depth and depth variability, and positively associated with other native fishes (including mountain sucker Catostomus platyrhynchus, redside shiner Richardsonius balteatus, and speckled dace Rhinichthys osculus). These findings on the distribution and ecology of northern leatherside provide important new information to assist successful management and conservation efforts within Wyoming and across the species' range.
Montana is home to 133 documented species of mayflies (Insecta: Ephemeroptera) from 55 genera in 16 families. This study reports on the conservation status, critical habitat, and management needs of 7 mayfly species that are currently listed as Montana species of concern (SOC) and 2 species that are currently listed as potential species of concern (PSOC). Six (67%) of these listed mayflies (Anepeorus rusticus, Analetris eximia, Homoeoneuria alleni, Lachlaniasaskatchewanensis, Macdunnoa nipawinia, and Raptoheptagenia cruentata) are associated with the sand and gravel benthic habitats of large prairie rivers. Two other mayfly species, Caurinella idahoensis (SOC) and Caudatella edmundsi (PSOC), are associated with small, densely forested streams of the Northern Rocky Mountain Refugium area of the Montana and Idaho border. Distributional data provided for Ametropus neavei (Ametropodidae) and Pseudiron centralis (Pseudironidae) may warrant these species being added to the SOC list. Records of the newest mayfly species recorded in Montana, Cercobrachys cree, are also discussed.
Netleaf hackberry (Celtis reticulata) is a deciduous shrub native to the southwestern United States and northern Mexico. Previous field observations have shown limited numbers of juvenile hackberries in the wild. This could be due to low germination and survival rates, but field germination trials have not been done. In the foothills of the Wasatch Mountains in Utah, hackberry shrubs have been shown to grow in association with boulders, likely using them as nurse objects. This experimental study field-tested germination and survival rates around boulders in this area. We located 26 boulders and planted 25 hackberry seeds on the north, west, south, and east sides of each boulder (n = 2600 seeds). In the following year, we counted the number of hackberry seeds that had germinated and become established near each of the boulders' sides. Overall, germination rates were extremely low, with only 55 (2.1%) of the planted seeds germinating and only 19 (0.7%) persisting until the end of the growing season. Among the few seedlings that survived, we found even fewer on the east sides of boulders. In the west-facing Wasatch Range, the east side of a boulder typically has a higher elevation than the other sides of a boulder and may expose hackberry seedlings to excessively dry conditions and erosion as precipitation collects in the lower areas around a boulder. Additionally, the microclimate-stabilizing benefits of a boulder may be limited for plants growing on the east side of a boulder because the morning sun is blocked by the Wasatch Mountains. The highest rates of germination were found on the comparatively shady and moist north sides of boulders where greater plant competition may limit long-term establishment of hackberry seedlings. Our study furthers our understanding of nurse associations in semiarid environments and can be applied by land managers seeking to utilize hackberry in site restorations.
The behavioral ecology of the American pika (Ochotona princeps) was investigated at a relatively hot south-facing, low-elevation site in the Mono Craters, California, a habitat quite different from the upper montane regions more typically inhabited by this species and where most prior investigations have been conducted. Mono Craters pikas exhibited a behavioral profile that contrasted significantly with that of pikas found in upper montane regions. Mono Craters pikas were less surface active than pikas in studies at high-elevation sites, although their rate of short-call vocalizations was similar. Mono Craters pikas did not exhibit typical foraging behavior: they fed and collected hay at significantly reduced rates, and did not construct large central-place hay piles. Social behaviors (conspecific aggression, social tolerance, avoidance) were infrequent compared with data from prior studies in upper montane environments. The Mono Craters site appears to be one of the warmest localities in which pikas have been observed. Recorded talus surface temperatures consistently exceeded 30 °C, and temperatures >40 °C were commonly recorded. In contrast, temperatures measured in the matrix of the talus were consistently cooler, and the apparent insulating effect of talus, as measured by the difference between surface and matrix temperatures, was typically most pronounced on the hottest days. Although pika activity was most frequent in early morning, late afternoon, and at night, pikas were also active during the hottest part of the day, presumably because of their ability to behaviorally thermoregulate by retreating into the cooler talus matrix. Data on populations of pikas which inhabit marginal sites can help us understand how pikas and other montane animals might respond in a world of climate change so that we may more effectively plan for their conservation.
Taking brood flush counts is a common sampling method that has been used for decades to estimate brood and chick survival in many gallinaceous bird species. However, brood survival estimates based upon flush counts may be biased because of low detection probabilities, occurrence of brood amalgamations, brood abandonment, and brooding adult mortality. Given that brood flush counts are still commonly used to estimate brood survival, and in some cases extrapolated to provide an estimate of chick survival, it is important to evaluate biases associated with this method. Therefore, we evaluated the use of brood flush counts to estimate brood survival of 2 gallinaceous birds: Northern Bobwhite (Colinus virginianus) and Scaled Quail (Callipepla squamata). To gain a better understanding of some of the mechanisms that may bias brood survival estimates, we radio-tagged Northern Bobwhite and Scaled Quail chicks (8–12 days old) and juveniles (4–6 weeks old) in 67 broods. We used radio-tagged chicks and juveniles to estimate and compare brood survival using 2 analysis methodologies. These methods included a telemetry method that relied upon radio-tagged chicks and a flush method that mimicked a brood flush count. In bobwhites, the brood survival estimates were higher with the telemetry-based estimate than with the flush estimate for both the 3-week chick (0.808 vs. 0.500) and 5-week juvenile (0.636 vs. 0.364). In Scaled Quail, the 2 brood survival estimates were similar at the chick (0.842 vs. 0.789) and juvenile (0.818 vs. 0.818) life stages. Because Scaled Quail have lower occurrences of brooding adult mortality and brood abandonment, flush counts provided a more accurate estimate of brood survival for Scaled Quail than for bobwhites. In situations where brood abandonment or brooding adult mortality is common, researchers using flush counts to investigate gallinaceous brood survival should consider the impact that these mechanisms may have on survival estimates.
We provide a record and field observations of California vole (Microtus californicus) based on a specimen collected on 5 June 2013 in riparian habitat from Arroyo San Rafael, northwestern Sierra San Pedro Mártir, Baja California, México. The last known record of this species in México was in 1974. This species was suspected to be extirpated from México; however, our recent record confirms its present occurrence in this country.
The first confirmed record of a live ocelot (Leopardus pardalis) in the state of Durango, and in La Michilía Biosphere Reserve, is reported here. This record is based on a photograph of an adult taken during a 2015 winter photo-trapping survey. This noteworthy record extends the ocelot's geographic distribution by >120 km from the nearest record in Sinaloa, Mexico. The record locality is also in oak forest at an unusually high altitude of 2750 m asl for an ocelot in Mexico.
We conducted a survey of the bat fauna of Desert National Wildlife Refuge (DNWR) in Nevada during 2008–2014. Our objectives were (1) to determine the species present at DNWR by mist-netting at likely bat drinking areas; (2) to compare the bat fauna at White Spot Spring at DNWR to the fauna documented there in 1962–1967; and (3) to assess the possible importance of artificial water sources to bats on this highly arid landscape in relation to an ongoing drought. We captured 480 bats of 10 species in mist nets over drinking water sources; species identifications are documented by voucher specimens. In order of frequency of capture, species and numbers of individuals captured were as follows: canyon bat (Parastrellus hesperus), 223; combined California myotis and western small-footed myotis (Myotiscalifornicus/M. ciliolabrum), 157; long-legged myotis (Myotis volans), 55; long-eared myotis (Myotis evotis), 12; Townsend's big-eared bat (Corynorhinus townsendii), 12; fringed myotis (Myotis thysanodes), 10; pallid bats (Antrozouspallidus), 7; big brown bats (Eptesicus fuscus), 3; and Yuma myotis (Myotis yumanensis), 1. California myotis and smallfooted myotis could not be reliably distinguished in the field because many individuals were intermediate in identifying characters. The abundance-based Jaccard's community similarity index for the bat community at White Spot Spring in April and July 2013–2014 compared with that from about 50 years earlier (O'Farrell and Bradley 1970) was 0.99 (SE bootstrap 0.02), indicating negligible change. Despite an ongoing severe drought, positive evidence for female reproduction was evident in July 2014. We suspect that DNWR could not sustain current levels of reproduction in bats without suitable drinking water sources.
The Bedford springsnail (Pyrgulopsis bedfordensis) is one of only 2 species of the genus Pyrgulopsis discovered east of the northern Continental Divide and appears restricted to one spring in central Montana. Due to its endemism, this species was placed on the Montana Species of Concern list as S1, critically imperiled. Despite the snail's rarity, nothing was known of this population's characteristics; it was last sampled in 1999. In 2015, I quantitatively sampled this population using a Hess sampler (n = 3) over a 40-m reach to determine the snail's benthic density and describe the associated macroinvertebrate community. Average densities of the springsnail were 30,540 live individuals per m2 (SE 2625) and 17,353 empty shells per m2 (SE 1389). Other benthic macroinvertebrates collected with the springsnail (11 taxa [SE 1.5]) were comparatively low in abundance, averaging 1533 individuals per m2 (SE 274). The Bedford springsnail population density at this Montana site ranks among one of the highest reported among its conspecifics.