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The drumming signals of 9 California stonefly species from 8 families are reported. Signal interval patterns of the individual interbeat, intragroup, and intergroup intervals are graphed and used to determine signal type (monophasic, varied beat-interval, diphasic, and grouped). Signals of Kathroperla takhoma Stark & Surdick are described for the first time. New signal characters and signals from additional locations are described for 8 species: Bolshecapnia maculata (Jewett), Calineuria californica (Banks), Doroneuria baumanni Stark & Gaufin, Megaleuctra complicata Claassen, Nemoura spiniloba Jewett, Oemopteryx vanduzeea (Claassen), Pteronarcys princeps Banks, and Sierraperla cora Needham & Smith.
Lack of knowledge about the distributions of plant and animal species can severely hamper management efforts. For invasive plants, distribution and abundance data can inform early detection and rapid response (EDRR) programs aimed at treating initial infestations. These data can be used to create invasion risk models at landscape and regional scales. Further, regional maps of invasive plant abundance are useful for communicating the scope of the invasive species problem to the public and policymakers. Here, we present a set of regional distribution maps for 10 problematic invasive plants in the western United States, created from the expert knowledge of weed managers in over 300 counties. Invasive plant experts identified infestations on paper, and the results were digitized into a regional GIS. Over 40% of requests were returned, resulting in maps with good spatial coverage and distribution data suitable for assessing invasive plant abundance across the western United States. Cheatgrass (Bromus tectorum) and Canada thistle (Cirsium arvense) were the most abundant and widespread of the surveyed species; however, the high concentrations and broad spatial extents of other invasive plants, such as hounds tongue (Cynoglossum officinale), white top (Lepidium draba), and Dalmatian toadflax (Linaria dalmatica), highlight the ongoing problems invasive species pose for western ecosystems, rangelands, and croplands. These results reinforce the critical role that regional mapping efforts can play in assessing and communicating invasion risk. This study suggests that knowledge about plant invasions exists locally and that experts are willing to participate in regional efforts to compile that information.
Where introduced, largemouth bass (Micropterus salmoides) are known to have negative effects on aquatic ecosystems. In this study, we used historical museum collection records (1942–2006) and contemporary (2009) collections to assess changes in the distribution of largemouth bass in the lower Boise River (southwestern Idaho). We also examined the stomach contents of largemouth bass collected during the contemporary survey to determine diet. Seventy-four large-mouth bass (45–137 mm TL) were represented in 13 historical collections from 5 lower Boise River locations. During autumn 2009, we sampled 8 sites in the lower Boise River for largemouth bass. Sixty-one largemouth bass (range 55–156 mm TL; = 84 mm) were captured from 5 sites downstream of a 4-m-high diversion dam. Largemouth bass were absent from all sites upstream of the dam. Our contemporary collection data extends the known distribution of largemouth bass 7.2 river km upstream. The long-term persistence (without recent stocking) of largemouth bass in the lower Boise River indicates that the fish may be spawning in the river and/or entering the system from external sources. Eighty percent of the largemouth bass collected in 2009 were <100 mm TL. Analysis of largemouth bass stomach contents revealed that aquatic insects (40%), crayfish (37%), and small-bodied fishes (11%) comprised much of the diet. Our study confirms that the largemouth bass has successfully established in the lower Boise River and that the species is piscivorous at small sizes (<100 mm TL). These findings suggest that largemouth bass could have a negative impact on native fishes in the lower Boise River.
Natural history information for rare plants can help land managers better understand the threats to extinction that a taxon may face. Our focus is on the natural history of Maguire primrose (Primula cusickiana var. maguirei, Primulaceae), an endemic, threatened plant found along a narrow corridor within a single canyon in northern Utah. We examined floral morphology, air temperature, relative humidity during flowering, dichogamy, blooming period, and visits from flying insects. As with most Primula, Maguire primrose displays distinct floral distyly. Within the distylous flowers, 17% of our samples had a timing difference in the maturation of anthers and stigmas, a trait not previously recorded in any other Primula species. Temperatures during the early-spring blooming period fluctuated widely between recorded minima below 0 °C and maxima above 33 °C. We captured 8 different species of flying insects visiting Maguire primrose flowers in air temperatures ranging from 6 to 15 °C. Bloom timing was not well synchronized between different canyon locations. Between different canyon locations, we observed only a small number of plants that overlapped in their flowering phenology. This threatened primrose variety has a cool, early-season blooming period, a dependence on visiting insects for outcrossing, and disjunct populations throughout the canyon, resulting in the potential for serious challenges to reproduction.
Climate change is predicted to increase the frequency of severe drought, yet little information exists on the impacts of drought on dominant trees of Mexican pine forests, which are among the most biologically diverse forests in the world. We conducted the first comparison of growth sensitivity to drought of two co-occurring Pinus species in Mexico to understand whether growth of dominant pines of the Sierra Madre Occidental in northern Mexico is sensitive to drought and temperature variation and to understand how sensitivity differs between tree species and elevations. We sampled and analyzed tree-ring data across a 400-m elevation gradient for the years 1945–2004 for co-occurring Pinus engelmannii and Pinus lumholtzii at Basaseachi National Park, Chihuahua, Mexico. We hypothesized that growth sensitivity to drought would be highest at low elevations, annual basal area increment (BAI) would be lowest at low elevations, and winter precipitation would covary positively with BAI at all elevations. Growth sensitivity to drought, as measured by a wet-dry ring-width index ratio (W:D), was significantly higher for both species at low elevations (W:D range 2.2–2.8) than at intermediate and high elevations (WD range 1.5–1.9). Pinus engelmannii had significantly higher W:D (2.2) than P. lumholtzii (1.8). Annual BAI did not differ between elevations or species. Annual ring—width index was positively and significantly associated with winter (December–April) precipitation. This association was stronger at low elevations than at high elevations. Other seasons of precipitation and other climatic variables were not significantly associated with annual growth. Our results suggest that the increasing frequency and severity of drought predicted for this region in the coming decades will reduce growth of P. engelmannii and P. lumholtzii, with greater impacts on low-elevation populations and on P. engelmannii.
Anthropogenic flooding to create wetlands is a management option intended to compensate for historical loss of natural wetlands in the Dry Mixedgrass Prairie of western Canada. It may help moderate or reverse declines in density of breeding Northern Pintails (Anas acuta L.) and other waterfowl. Little information exists, however, on breeding waterfowl use of created wetlands flooded at different seasons and frequencies. This study assessed the effects of 2 flooding seasons (fall and spring) on abundance of breeding Northern Pintails and other ducks within newly created wetlands. Additionally, we compared breeding waterfowl use of sites with spring and fall flooding by using 2 treatments (1 year vs. 2 years of flood cessation) intended to alter vegetation composition and density (measured as visual obstruction) on older wetlands currently dominated by cattail (Typha latifolia L.). Vegetation density was assessed across the landscape in all treatments. While recently initiated fall and spring flooding each increased breeding duck densities compared to naturally flooded wetlands, spring flooding led to a greater density of Northern Pintails and other ducks in 1 of 3 years. Within established wetlands, 2 years of flood cessation led to a marked decline in duck abundance, while removal of flooding for one year led to the greatest duck abundance, even compared to wetlands with sustained fall flooding. Finally, vegetation density (i.e., visual obstruction) varied by flooding treatment and year of sampling, and was an important predictor of use of created wetlands by both Northern Pintails and other duck species. Collectively these results indicate that duck use of managed wetlands in the Dry Mixedgrass Prairie of western Canada can be maximized with carefully planned flooding treatments that include spring flooding in newly created wetlands and intermittent flooding in established wetlands.
In summer, bands of sheep are grazed in western North American mountains. At night the sheep are concentrated into bedding areas. In the study area, each bedding area is only utilized by sheep for one night a year for 2 out of 3 years. Vegetation in the bedding areas was compared to vegetation outside these areas. Both perennial forb cover and total perennial cover were greater outside (48% and 61%, respectively) than inside (29% and 36%, respectively) the bedding areas. Annual forb cover one year after sheep grazing was greater inside (17%) bedding areas than outside (5%). Immediately after sheep bedding, total forb cover was greater outside the bedding areas. Forb and grass biomass were greater outside the bedding areas compared to inside. Total vegetation biomass outside (240 g · m-2) the bedding areas was more than double the amount inside (86 g · m-2) immediately after bedding. In the year after bedding, vegetation biomass inside the bedding areas increased, but was still less than outside. Sheep bedding areas were not invaded by nonnative plants. Sheep bedding reduced vegetation quantity and changed relative abundance of annual forbs. Vegetation in the bedding areas was resilient to grazing impacts, and long-term use of sites in this ecosystem does not significantly degrade vegetation.
Lake Mohave, on the lower Colorado River in Nevada and Arizona, was created by the construction of Davis Dam for power generation, flood control, and water supply. Management has led to the periodic lowering of the water level of the reservoir (drawdown), such that it reveals a gradient of zones around the margins of the reservoir that range from frequently inundated to frequently dry. The initial filling of Lake Mohave flooded the preexisting native riparian woodlands of Populus-Salix (cottonwood-willow), creating a new shoreline and plant community. We analyzed the spatial distribution of the plant species that dominate the plant community (i.e., native Salix gooddingii C.R. Ball [Goodding's willow] and nonindigenous Tamarix ramosissima Ledeb. [saltcedar]) and the soil components to discern patterns. Data analyses and modeling indicate that there are 3 emergent patterns in the distribution and composition of vegetation and soils. First, even though both S. gooddingii and T. ramosissima were present in the inundated zones, there were more mature S. gooddingii individuals in the frequently inundated reaches, while T. ramosissima presence and cover increased with distance from the water's edge. Salix gooddingii seedlings were not observed, but T. ramosissima seedlings were present in all zones. The only regeneration of S. gooddingii was vegetative. Naturally occurring Populus fremontii S. Watson (Fremont cottonwood) was completely absent in the drawdown and upland plant communities. Second, soil salinity and pH values range from 49.4 to 0 dS · m-1 and 6.4 to 9.4, respectively, and varied significantly with landform type and geographic location along the reservoir. Patterns in soil chemistry may be related to shore geomorphology that either shelters or exposes soils to wave action, which mechanically agitates, aerates, and flushes soils. Presence of Salix gooddingii in the frequently inundated zones and the co-occurrence of T. ramosissima and relatively high soil salinity concentration reflect patterns among plant flood tolerance and soil responses to periodic inundation. While reasons for the absence of P. fremontii are unknown, the absence of S. gooddingii seedlings may be related to the fact that seed release coincides with the period when the reservoir is at its highest, thereby limiting recruitment. Third, the only regeneration of S. gooddingii appeared to have occurred following herbivory (Castor canadensis Kuhl [North American beaver]) and wind damage. We conclude with suggestions for the conservation of novel riparian ecosystems as surrogates for lost native ecosystems. These suggestions include manipulating reservoir water levels to simulate natural fluvial processes so that nonnative plant establishment is inhibited, excessive soil salts are flushed from the system, and native transplants can be established.
Activity patterns of animals can vary depending on both endogenous and environmental factors. Although black bears exhibit substantial variation in activity across the year, relatively little is known about how daily activity patterns and associated movement rates differ among sex and age classes across seasons. We used fine-scale movement data from black bears fitted with GPS collars to evaluate movement and activity patterns across sex and age classes for daily and seasonal time periods in relation to mating and foraging behavior. Black bears were most active during crepuscular time periods, moderately active during the day, and least active at night, which is consistent with previous research on black bear activity patterns in areas where bears were not greatly influenced by human activities. However, during spring and early summer, adult males moved significantly more during the crepuscular time period than they did during late summer and fall. Female and subadult males exhibited very similar activity patterns between seasons; and during late summer and fall, all bear classes exhibited similar activity patterns across daily time periods. Differences in activity patterns of males between seasons were potentially related to extensive movements undertaken during the mating season. Although adult males exhibited lower movement rates in late summer and fall compared to spring and early summer, females and subadult males did not appear to reduce movement rates during the late-summer berry season. Our research reveals that, although bear classes exhibit similar temporal patterns of daily activity and inactivity, the magnitude of movement rates revealed differences in activity patterns among bear classes, which allowed us to better understand factors influencing activity in animal populations.
Velvet lupine (Lupinus leucophyllus Dougl. ex Lindl) contains the teratogenic alkaloid anagyrine that causes a crooked calf syndrome. An outbreak of crooked calves occurred in the Channeled Scabland region of eastern Washington in 1997 following 2 years of above-average precipitation. Following this catastrophic loss, we began studies to track velvet lupine density and relate its population cycle to precipitation. In the first study, five 1-m2 quadrats were systematically placed in dense lupine patches at each of 5 locations throughout the scabland region. The quadrats were permanently marked and the number of seedlings and established mature plants were counted biweekly or monthly through the growing seasons of 2001–2005. In the second study, four 1 × 30-m belt transects were established at each of 3 additional locations in the scabland region. The number of seedlings and mature lupine plants were counted within these transects in June or July each year from 2002 to 2009. A third study was conducted to determine the slope or aspect where lupine was most abundant. Ten sites were located along the Cow Creek drainage which runs through the region. At each site, 1 × 10-m belt transects were established in alluvial bottoms, slopes, and shallow rocky ridges. In study 1, density of mature lupine plants generally declined between 2001 and 2005 (P < 0.001) and was correlated with spring precipitation (r = 0.77). In study 2, density of mature lupine plants differed between years (P < 0.001), declining from 2002 through 2005 but increasing in 2007 in response to heavy precipitation the previous fall and spring (mature lupine plants vs. fall precipitation, r = 0.75; and mature lupine plants vs. spring precipitation, r = 0.62). Density of lupine was greatest on slopes (2.6 plants · m-2), intermediate on alluvial bottoms (1.5 plants · m-2), and lowest on shallow rocky ridges (0.26 plants · m-2). Velvet lupine populations appear to cycle with climatic patterns, increasing following wet years and dying back in drought.
Temperature is a critical factor in the distribution of stream fishes. From laboratory studies of thermal tolerance, fish ecologists can assess whether species distributions are constrained by tolerable thermal habitat availability. The objective of this study was to use lethal thermal maxima (LTM) methodology to assess the upper thermal tolerance for mountain sucker Catostomus platyrhynchus, a species of greatest conservation need in the state of South Dakota. Adult fish were captured from wild populations in the Black Hills of South Dakota and acclimated to 20, 22.5, and 25 °C. Four endpoints (3 sublethal, 1 lethal) were recorded, with death being the most precise (lowest SE, easily discernible). The LTM for mountain sucker was 34.0 °C at 25 °C acclimation, 33.2 °C at 22.5 °C acclimation, and 32.9 °C at 20 °C acclimation. Compared to co-occurring species in the Black Hills, the LTM of mountain sucker is higher than that of salmonids but lower than that of 3 cypriniforms. Mountain sucker LTM is intermediate compared to other species in the family Catostomidae. These results suggest that the mountain sucker is not currently limited by water temperatures in the Black Hills but may be affected by stream warming as a result of climate change.
A road-killed specimen of a large male ocelot (Leopardus pardalis) was salvaged on March 2010 from Palo Pinto County in north central Texas. Our review of the northern biogeography of the species indicates that the specimen is not out of historical context. The possibility that the animal represents a broader range of sparsely distributed individuals within the elusive cat's known historical range deserves consideration.
Greater Sage-Grouse (Centrocercus urophasianus) depend on sagebrush habitat for food and cover during winter, yet few sage-grouse winter ecology studies have been conducted. During January and February 2007, we monitored 22 radio-collared sage-grouse (7 females and 15 males) in central Oregon to characterize winter habitat use and movement patterns. We estimated distances traveled between locations on a weekly basis and quantified habitat characteristics at locations used by male and female sage-grouse. The birds we collared moved extensively across the landscape, using approximately 1480 km2. Sagebrush canopy height in sites used by sage-grouse varied from 0.25 to 0.75 m, with females tending to be found in sites with taller sagebrush and less foliar cover than in sites where we found males. The difference in foliar cover between sexes was related to a seasonal change in habitat use: 4 females found in little sagebrush (Artemisia arbuscula) in January and early February were no longer located nor found foraging in little sagebrush after 15 February. Also, by this date, most male sage-grouse had stopped using big sagebrush (Artemisia tridentata) as they migrated to leks. Sage-grouse mortality rates were low during our study, which may be attributed to the study area receiving half the long-term average amount of snow. The large area over which sage-grouse moved during winter indicates that conservation of Greater Sage-Grouse may require preservation of sagebrush at landscape scales (thousands of square kilometers).
In a pilot study, I observed a relationship between domestic livestock grazing and location of American pika (Ochotona princeps) haypiles in the eastern Sierra Nevada and several Great Basin mountain ranges. Where vegetation communities adjacent to talus bases (forefields) were grazed, mean distance from the talus borders to the closest fresh haypiles was 30.1 m (SD = 18.9 m, n = 27), and haypiles were found only high in the talus. In ungrazed forefields, mean distance was 1.8 m (SD = 0.9 m, n = 57), and haypiles were found along the low-elevation talus—vegetation border. Where grazing was active, haypiles consistently contained vegetation gathered from plants growing within the talus. Talus vegetation appeared to be of lower diversity and the plant species of lower nutritional value than forefield plants. This difference, if real, would compromise quality of forage for summer browsing and winter haypile storage. This condition, combined with potentially less favorable summer and winter thermal conditions of upper talus locations relative to lower talus borders, suggests that grazing might be a factor compromising population conditions and status of pikas. Recent studies have reported higher extirpation rates of pika populations in Great Basin ranges (primarily in Nevada) than in adjacent regions. Because domestic livestock grazing is widely permitted on public lands throughout pika habitat in the Great Basin but not permitted (or much more restricted) in pika habitat of the Sierra Nevada, California, grazing effects might be contributing to observed regional differences in viability of pikas.
Alpine plant species are thought to have limited phenotypic plasticity, but few data exist on forbs. We assessed plasticity in allocation of biomass to belowground and aboveground parts and to reproduction in 5 forb species from a 50-year-old disturbance and adjacent undisturbed areas in an alpine dry meadow. Three of the species, mostly those with variable numbers of stems per genet, increased in size in the disturbed areas. All 5 forbs showed very limited plasticity in allocation of biomass. Lack of phenotypic plasticity in these forbs may limit their ability to respond to future changes in environment.