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Nest-area fidelity is common among many birds including those in the orders Anseriformes, Ciconiiformes, and Procellariiformes. Successful nesting attempts are often associated with a higher probability that nesting adults will return in a consecutive year. Conversely, unsuccessful birds are often less likely to show fidelity in subsequent years. Despite substantial natural history information from across the range of Greater Sage-Grouse (Centrocercus urophasianus), the prevalence of sage-grouse nest-area fidelity remains unclear. Our objectives were to (1) determine if individual female sage-grouse showed fidelity to nesting areas in subsequent years, (2) test whether successful females were more likely to demonstrate fidelity than unsuccessful females, and (3) examine the distance between nest sites and active leks in Strawberry Valley, Utah. We observed 30 radio-marked females that attempted a nest in consecutive nesting seasons between 1998 and 2010. The mean distance between initial year's nests and subsequent year's nests ( = 1459 m, SE = 84.9 m) was lower (P < 0.01) than the mean distance from initial year's nests to random nests ( = 13,263 m, SE = 227.5 m) indicating that sage-grouse demonstrated nest-area fidelity. We found no support (P > 0.05) for the hypothesis that successful females (n = 17, = 1355 m, SE = 142.6 m) were more likely to nest closer to the previous nest location than unsuccessful females (n = 13, = 1595 m, SE = 214.9 m) in our study area. Mean distance from all nests (n = 181) to nearest active lek was 4.3 km. We found only 57% of our nests located within the 3.2-km distance from an active lek often used to delineate critical nesting habitat. We suggest a more conservative distance of 10 km for our study area and consideration of nest-area fidelity in conservation planning.
Establishment of sampling frameworks to monitor the occurrence of ecological indicators and to identify the covariates that influence occurrence is a high-priority need for natural resource restoration and management efforts. We utilized occupancy modeling to identify patterns of beaver occurrence and factors influencing these patterns (i.e., type and amount of vegetation cover) in the Grand Canyon of the Colorado River ecosystem. We used rafts and kayaks to access a stratified random sample of sites (i.e., 100-m-long sections of riverbank) and used repeated sampling procedures to sample for beaver sign (i.e., lodges, cuttings, tracks, and beaver sightings). We quantified the type and amount of vegetation cover at each sampled section by using a GIS database of remotely sensed information on the riparian vegetation in the Grand Canyon. We first modeled occurrence of beaver sign as a function of the total amount of vegetation cover (summed across classes) and then determined the relative importance score for each of the 7 vegetation classes. Detection probability (p) was 2 times higher when observers traveled in kayaks (0.61) than when they traveled in rafts (0.29). Occurrence of beaver sign (ψ;) in sampled transects was widespread throughout the Grand Canyon (ψ; = 0.74, SE = 0.06) and positively associated with total vegetation. The relative importance scores for Tamarix and Pluchea vegetation classes were 1.5–2.5 times larger than those for all other vegetation classes, indicating that occurrence of beaver sign was most strongly associated with the cover of these 2 vegetation classes. Our results imply that quantifying the amount of riparian vegetation in close proximity to a river helps determine the occurrence of an important ecological indicator in riparian systems. The results also demonstrate a useful and cost-effective method for monitoring riverine species' usage patterns by explicitly accounting for detectability.
Described as new from Moffat and adjacent Rio Blanco counties, Colorado, are 4 taxa: Chrysothamnus nauseosus (Pallas) Britton var. linearifolius S.L. Welsh & S. Goodrich, var. nov.; Erigeron nematophylloides S.L. Welsh & A. Huber, sp. nov.; Lepidium montanum Nuttall var. diffusum S.L. Welsh & S. Goodrich, var. nov.; and Iva axillarisPursh var. parvifolia S.L. Welsh & A. Huber, var. nov.
Eccentricity of stems of Artemisia tridentata Nutt. (big sagebrush) has been reported previously. Analysis of samples observed over 2 years documented that each stem terminal produces about 8–10 branches each year, and during second-year growth, 3–8 of these develop into short, flowering, determinate branches. Each flowering branch produces hundreds of seeds and then dies at the end of the season, while the other vegetative branches persist. However, growth of the determinate flowering branches causes the death of vascular cambium surrounding their attachment points on the main stem. This death then results in the observed eccentric growth of the stein. In a separate experiment, when presumptive flowering branches were removed prior to elongation, the vascular cambium of the stem was not destroyed, and no eccentric growth occurred. Since the vascular cambium is responsible for continued wood production, the effect of these areas of cambial death is amplified during subsequent years and leads to weak stem segments and possibly to limitations on overall growth. Nevertheless, in spite of these negative side effects, flowering stem growth provides for ample seed production year after year. This peculiar eccentric growth phenomenon, coupled with the anomalous interxylary cork that has also been reported for Artemisia tridentata, supports the idea that this and related species are descended from an herbaceous ancestry and have therefore evolved their rather imperfect woodiness secondarily.
Neviusia cliftonii (Rosaceae), the Shasta snow-wreath, is an endemic shrub found in the vicinity of Shasta Lake, Shasta County, California. First described 20 years ago, the species is of conservation concern due to its restricted range, a low number of known populations, and the potential impacts on or threats to many of these populations. To assess the genetic structure of N. cliftonii, 21 of the 23 known populations were sampled for isozyme analysis. Genetic and multivariate analyses were used to assess levels of genet (genotypic) diversity, allelic variation, and population differentiation. When assessed at 17 loci, a total of 48 multilocus genotypes were identified in the collection of 410 samples, indicating N. cliftonii is capable of significant vegetative reproduction. Five populations were composed of a single genet each, with an average of 3.14 genets per population and a maximum of 15 genets in a single population, Allelic diversity was low, with a maximum of 3 alleles observed at one locus. Populations were differentiated, with 85% of the allele frequency variance distributed among populations. Multivariate analysis identified 3 clusters of genetically similar populations: one cluster composed of 15 populations, a second cluster composed of 5 populations, and one population being distinct. Individuals from the distinct population displayed unique alleles at 2 loci (AAT-1 and AAT-2). The distribution of populations among clusters did not correspond to geographic (watershed) or substrate classifications, indicating that additional, unmeasured factors may influence the genetic structure of this species.
Benthic macroinvertebrates are integral components of stream ecosystems and are often used to assess the ecological integrity of streams. We sampled streams in the upper Clear Creek drainage in the Klamath—Siskiyou Ecoregion of northwestern California in fall 2004 (17 sites) and 2005 (original 17 plus 4 new sites) with the objectives of documenting the benthic macroinvertebrate assemblages supported by the streams in the area, determining how those assemblages respond to environmental variables, assessing the biological condition of the streams using a benthic index of biotic integrity (IBI), and understanding the assemblages in the context of biodiversity of the ecoregion. We collected both reach-wide (RW) and targeted-riffle (TR) macroinvertebrate samples at each site. The macroinvertebrate assemblages were diverse, with over 150 genera collected for each sampling protocol. The macroinvertebrate assemblages appeared to be most responsive to a general habitat gradient based on stream size, gradient, flow, and dominance of riffles. A second important habitat gradient was based on elevation and dominance of riffles. A gradient in water quality based on concentrations of dissolved ions and metals was also important. Models based on these 3 gradients had Spearman's rank correlations with macroinvertebrate taxonomic composition of 0.60 and 0.50 for the TR and RW samples, respectively. The majority (>50%) of the sites were in good or very good biological condition based on IBI scores. The diversity of macroinvertebrate assemblages is associated with the diversity of habitats available in the Klamath—Siskiyou Ecoregion. Maintaining the aquatic habitats in good condition is important in itself but is also vital to maintaining biodiversity in this diverse and unique ecoregion.
I studied the ecology and behavior of ringtails (Bassariscus astutus) in juniper (Juniperus monosperma) woodland on the Sevilleta National Wildlife Refuge in central New Mexico. Average home-range sizes of ringtails (males 462 ha, females 94 ha, 95% fixed kernel) were among the largest reported to date. Females moved least in summer and most in autumn, but males showed no seasonal trend in movements. The average stay in a single den was 1.3 days. I found no effect of the closeness of approach of the den observer on the distance moved between successive dens. Ringtails used a variety of den settings: rocks, trees, shrubs, rocks and shrubs, and holes in the ground. Males used trees and rocks more and shrubs less than females. In summer and autumn, ringtails used rocks more and shrubs less than expected, and in winter ringtails used rocks less and shrubs and holes in the ground more than expected. There was no tendency to reuse certain types of dens, and 31.6% of dens were reoccupied at least once. Most ringtails died before the age of 4 due to predation, resulting in an annual survival rate of 0.375. Contrary to the popular conception that ringtails require open, permanent water for survival, 16 of 18 ringtail home ranges had no water source within them, and no ringtail was observed in the vicinity of water. Latrines of ≥2 scats contained 89.4% of scats found. As measured by frequency of occurrence in scats, ringtails consumed primarily fruits, followed by arthropods, mammals, birds, and reptiles, Many arthropod prey were venomous or chemically defended. Average weights were 1.0 kg for males and 0.9 kg for females.
Alien plant species often use areas of heavy human activity for habitat and dispersal. Roads and utility corridors have been shown to harbor more alien species than the surrounding vegetation and are therefore believed to contribute to alien plant persistence and spread. Recreational trails represent another corridor that could harbor alien species and aid their spread. Effective management of invasive species requires understanding how alien plants are distributed at trailheads and trails and how their dispersal may be influenced by native vegetation. Our overall goal was to investigate the distribution of alien plants at trailheads and trails in the Rocky Mountains of Colorado. At trailheads, we found that although the number of alien species was less than the number of native species, alien plant cover ( = 50%) did not differ from native plant cover, and we observed a large number of alien seedlings in the soil seed bank, suggesting that alien plants are a large component of trailhead communities and will continue to be so in the future. Along trails, we found higher alien species richness and cover on trail (as opposed to 4 m from the trail) in 3 out of 4 vegetation types, and we observed higher alien richness and cover in meadows than in other vegetation types. Plant communities at both trailheads and trails, as well as seed banks at trailheads, contain substantial diversity and abundance of alien plants. These results suggest that recreational trails in the Rocky Mountains of Colorado may function as corridors that facilitate the spread of alien species into wildlands. Our results suggest that control of alien plants should begin at trailheads where there are large numbers of aliens and that control efforts on trails should be prioritized by vegetation type.
The Sierra San Pedro Mártir (SSPM) in northern Baja California, Mexico, is a remote mountain at the southern edge of the California Floristic Province, a vegetation type that includes the Sierra Nevada of California and western Nevada. Unlike most forests in the southwestern United States, the forests of the SSFM have never been logged and have experienced only light grazing in recent years, and wildfires have not been suppressed until recent decades. The SSFM represents one of the best examples of an intact presettlement forest in the California Floristic Province. We investigated the mode of seed dispersal of Jeffrey pine (Pinus jeffreyi) in the SSPM, and compared it to that from the eastern slope of the Sierra Nevada, to determine how this process might differ between nearly pristine and heavily altered forests. We found that seed dispersal appears to occur by the same means in both forests (i.e., scatter hoarding of seeds by rodents), but that seedling establishment is much less successful in the SSPM. We considered several hypotheses for why this difference might exist, including the size of seed crops, fire regimes, climate change, grazing by domestic ungulates, and lack of facilitation by shrubs (i.e., nurse plants), but none of these explanations appears adequate to account for the difference. Instead, we suggest that the slow rate of seedling establishment at the SSPM is due to a greater consumption of seeds cached by California chipmunks (Tamias obscurus), who experience a relatively long period of euthermic winter activity in the warm climate of the SSPM. This greater consumption leaves few seeds to germinate. Future studies should test the relative importance of these alternative causes for low seedling recruitment at the SSPM.
Postfire revegetation with native perennial grasses is difficult to achieve in disturbed arid rangelands. If local populations are adapted to current conditions, then locally collected seed would be predicted to have higher survival than nonlocal seed, and using local seed should improve revegetation success. However, for revegetation projects in the Great Basin, sufficient quantity of local seed is often difficult to obtain commercially, so seeds often originate from source populations that are hundreds of kilometers from the project site. We investigated whether seed source affected first-year establishinent of big squirreltail (Elymus multisetus M.E. Jones) seedlings in a common garden field trial 50 km north of Reno, Nevada. For the trial, we used wild, locally collected seed and commercially produced seed originating from Oregon, Idaho, and California. Several phenological and growth traits varied significantly between source populations. Eighty-six percent of local seeds emerged, compared to 71%, 61%, and 12% of seeds from Idaho, Oregon, and California, respectively. Local seeds emerged, on average, 9 days earlier than seeds from other sources. Fourteen percent of the local seedlings survived through the first year, exceeding survival by Oregon (12%), Idaho (8%), and California (2%) seedlings. Though survivorship was highest for local seed, local seedlings were smaller, producing 24% fewer leaves than the most productive seedlings from the Idaho seed source. Our data suggest that seed source is an important factor in seedling establishment. If local seed can survive significantly better than regionally collected, commercially produced seed, it may be both ecologically and economically beneficial to use local seed in revegetation.
Distribution of the plains pocket mouse (Perognathus flavescens) overlaps tallgrass prairies in northeastern parts of the species' range in the central United States. Distribution and abundance of the plains pocket mouse appears negatively impacted by agricultural practices during the last century due to the scarcity of records throughout the region. In eastern Nebraska, few plains pocket mice have been captured and no published account exists in recent decades. We investigated the current status of P. f. perniger, the eastern subspecies in Nebraska, because of a paucity of information regarding this subspecies' natural history and suspected extirpation from the state. We captured 56 P f. perniger in 13 counties in northeastern and east-central Nebraska in 2008, including 10 counties lacking prior records. We also obtained data on its presence in extreme eastern Nebraska (Douglas and Lancaster counties) via a literature review and query for specimens in museums. Some individuals without darker-colored guard hairs represented the eastern limits of the western subspecies P. f. flavescens associated with the easternmost extent of the Sandhill Region of the state or other isolated sandy habitats. Across eastern Nebraska, many sites with captures of plains pocket mice appear to represent strongholds associated with isolated areas of friable, sandy soils. To date, presence of the species has not been detected in southeastern parts of the state. Conservation of habitats with sandy soils, along with implementation or continuance of disturbance regimes (i.e., grazing), will benefit this species and a number of other sand-adapted species in eastern Nebraska.
Douglas' dustymaiden, Chaenactis douglasii (Hook.) Hook. & Arn., is a widespread, inconspicuous, short-lived perennial wildflower that blooms in early summer and is found in basin sagesteppe to upper montane areas throughout the U.S. Intermountain West. The species is proving practical to grow for seed and is expected to be used for western rangeland rehabilitation. Through manual pollination experiments, C.douglasii was found to be only weakly self-fertile; 15% of flowers from geitonogamy and autogamy treatments yielded filled achenes. In contrast, 57% of outcrossed flowers produced achenes filled with endosperm, with every capitulum yielding some fertile seeds. Freely visited flowers from a wild population produced 91% fertile achenes, indicating that seed production was not pollinator limited. Floral visitors to C. douglasii were sparse, consisting entirely of bees, most of them floral generalists. Museum specimens of bees taken at C. douglasii and 3 closely related congenerics comprise 175 species in 39 genera and all 6 North American bee families. A population of the manageable mesolectic cavity-nesting bee, Osmia californica, when released at one sagesteppe site, provisioned its cells primarily with pale, spiny pollen resembling that of the C. douglasii growing at the site. This bee and the honey bee appear most promising for pollinating dustymaiden that is being farmed for seed.
Habitat fragmentation is hypothesized to influence movements of animals between isolated habitat fragments and to affect survival of animals moving between fragments. Translocation experiments can provide quantitative information on movements and survival. We assessed potential barriers to dispersal and survival of pygmy rabbits (Brachylagus idahoensis), a species of conservation concern that is hypothesized to be sensitive, after translocation, to fragmentation of its sagebrush habitats. We measured homing tendency and estimated survival of pygmy rabbits after short-distance (1–2 km) experimental translocations at sites in southeastern Oregon. We captured, radio-tagged, and translocated 59 pygmy rabbits across 3 landscape categories of habitat fragmentation. We used logistic regression to compare among landscapes the odds of homing, after accounting for sex and displacement distance of individuals. We used known-fate models in program MARK to estimate survival rates of rabbits after translocation. Fifteen percent of translocated pygmy rabbits successfully homed to within 150 m of their original capture locations. Individuals translocated across fragmented landscapes with patchy cover of big sagebrush were the most likely to home, whereas rabbits translocated across relatively continuous big sagebrush cover bisected by a road were least likely to home. We also found that pygmy rabbits that homed had higher survival rates than those that did not return to their hoirie areas, and rabbits that settled near roads had lower survival rates than those that did not settle near roads. The proximity of the largest patch of big sagebrush also had a positive influence on the survival of rabbits after translocation. Our results indicate that fragmentation does not necessarily impede movements nor does it necessarily reduce survival.
Population studies of the dunes sagebrush lizard (Sceloporus arenicolus) suggest that fluctuations in the population dynamics of this lizard are driven by spatial and temporal variation in annual recruitment. Although variation in survival of eggs or embryos is known to contribute greatly to variation in annual recruitment in many other lizard species, little is known about these early life history stages and their contributions to the population dynamics of S. arenicolus. Here we describe the first 3 observations of nesting in the wild for S. arenicolus. All observations took place between 2005 and 2011 at Caprock Wildlife Area, 48 km east of Roswell, New Mexico. From these observations, we supplement existing knowledge of these early life history stages, which can inform working models of life history evolution for this lizard endemic to the Mescalero Sands and Monahans Sandhills ecosystems.
Diet items and ectoparasites were identified from 15 southern short-tailed shrews (Blarina carolinensis) captured during a one-year study (December 2009—November 2010). Twenty different diet items were found in 13 southern short-tailed shrews. Collectively, insects made up the bulk of these shrews' diet (92%), with Diptera and Hymenoptera being most prevalent. Plant material and arachnids occurred 46% of the time. Six of the diet items identified are new reports for the southern short-tailed shrew. Nine ectoparasite species were collected from 11 of the southern short-tailed shrews, comprising 8 species of mites and one species of tick. Orycteroxenus soricis and Androlaelaps fahrenholzi were the most frequent (36%) ectoparasites collected. Two of the ectoparasites (Ornithonyssus bacoti and Ixodes scapularis) are new host records, and 5 of the 8 species of mites collected were not previously reported as occurring in Louisiana.
We report the southernmost records of the spotted skunk (Spilogale gracilis) and the ring-tailed cat (Bassariscus astutus) for the state of Baja California, México. We also report the first specimens of the California chipmunk (Neotamias obscurus meridionalis) for the Central Desert of Baja California.