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Pocket gophers are of great importance both for their function in ecological systems and for their impact on anthropogenic environments. Managing pocket gopher populations requires a fundamental understanding of population demographics, specifically sex ratios; yet quick and reliable techniques for visually identifying gender of pocket gophers are lacking. We developed a visual identification method based on external characteristics of genitalia and mammae that allows for rapid, yet correct assessment of gender in pocket gophers. This approach was particularly accurate (>99%) for visual identifications in the field. Our approach was also accurate (>98%) for frozen specimens, although care must be taken when identifying gender of frozen, immature pocket gophers. Although our results pertain specifically to Thomomys talpoides and Thomomys bottae, we believe that our methodology can be broadly applied to additional pocket gopher species.
We explored the notion that small canals could be good experimental proxies of streams by documenting physiochemical parameters and macroinvertebrate community development in an aridland irrigation canal. Further, we tested the production-compensation hypothesis between benthic invertebrates and invertebrates in the water column (drift). If the hypothesis held, invertebrates in the drift would be low until the benthic carrying capacity was reached; then organisms in the drift would increase as individuals avoided overcrowded conditions in the substrate. In a small, naturalized freshwater canal, we sampled macroinvertebrates in the substrate and those in the drift once every 2 weeks over 170 days (May–October). We placed macroinvertebrates into functional feeding groups (FFG) and examined these groups along with total density and taxa richness. We found no density-dependent relationship either in FFG or total density between the benthos and invertebrates in the drift. Our negative results might indicate that the stream benthos did not reach carrying capacity (partially affected by adult emergence in the autumn), the invertebrate dynamics in the canal did not adequately represent those occurring in a natural stream, or the duration of our study was too short. However, the invertebrate community in the canal did follow community buildup patterns for small streams reported in the literature, and it also resembled the community in a nearby natural stream. We suggest that naturalized canals could be used as “mesocosms,” mimicking small natural streams, in which highly manipulative experiments could be conducted. In addition, the effects of temporary and permanent canals across the arid western landscape have been understudied and represent a new area of ecological research.
Reproductive strategies vary among freshwater fishes. Information on reproductive characteristics is important for water managers' efforts to protect and recover imperiled species. We describe aspects of the reproductive ecology of Pecos Bluntnose Shiner (Notropis simus pecosensis). We determined gonadosomatic index, examined ovarian condition, and counted mature ova to determine the seasonal reproductive timing and duration of Pecos Bluntnose Shiner in the Pecos River, New Mexico. Monthly changes in gonadosomatic index, ovarian stage, and number of mature ova per female suggest that Pecos Bluntnose Shiner has a reproductive season extending from April through September, with a peak occurring in June and July. In July, 93% (n = 44) of female Pecos Bluntnose Shiner were in reproductive condition, regardless of size. The highest number of mature ova counted (1498) was observed in a 59.5-mm (standard length) female from June 2009. Peak spawning activity coincides with sustained water releases from reservoirs; these releases have higher peaks and longer duration than natural rainfall events. Results of this study provide important insight on the reproductive biology of a threatened fish and may be useful in long-term conservation planning.
We examined the incidence of bark beetle (Coleoptera: Curculionidae: Scolytinae) colonization and subsequent mortality, and the presence of dwarf mistletoe (Arceuthobium vaginatum subsp. crytopodum) within a rare remnant old-growth stand of ponderosa pine. In 2011, 96% of the old growth trees were remaining with additional dense ingrowth of ponderosa pine (Pinus ponderosa Douglas ex. Lawson) within the understory of the oldest trees. We compared the old-growth stand to abutting stands of ponderosa pine: a low-density seed-tree cut and a high-density post-1900 second growth. The old-growth stand had levels of bark beetle colonization similar to the seed-tree stand, and both of these stands had significantly more bark beetles than the high-density stand. Across all sites, bark beetles were found in higher numbers in the 51–60 cm diameter class. We found a trend between the proportion of trees infected per site and the percentage of trees with bark beetle activity, although a direct relationship between a tree's dwarf mistletoe infection and beetle attack was not found. This work indicates that large, older trees are not immune to endemic bark beetle attack and subsequent mortality. In light of current efforts to implement forest restoration practices that favor older and larger trees, managers of ponderosa pine forests should be aware that risk from bark beetle attack may increase as basal area increases within the stand.
Conservation of avian species requires understanding their nesting habitat requirements. We compared 3 aspects of habitat at nest sites (topographic characteristics of nest sites, nest placement within nest sites, and canopy stratification within nest sites) of 2 related species of ground-nesting warblers (Red-faced Warblers, Cardellina rubrifrons, n = 17 nests; Painted Redstarts, Myioborus pictus, n = 22 nests) in the Sky Island mountain ranges of southeastern Arizona. These species nested in several forest and woodland cover types that occurred along an elevational gradient. Red-faced Warblers nested primarily toward the upper end of that gradient, in pine (Pinus spp.)—oak (Quercus spp.) and mixed-conifer forests. Painted Redstarts nested primarily at lower elevations, in riparian forest, oak-pine woodlands, and pine-oak forest. The 2 species both nested in cover types that occurred at mid-elevations. Within these shared cover types, Red-faced Warblers nested at higher elevations and at nest sites with greater canopy cover >10 m aboveground than Painted Redstarts. Nest placement within nest sites was similar between species; both placed their nests in concealed locations. Our results suggest that managers should consider the entire elevational gradient surveyed here to best conserve habitat for both species, and should maintain at least some areas with relatively dense understory cover across that gradient to provide cover for nest sites. Managers should emphasize lower overstories in lower-elevation oak-pine woodlands, taller overstories in higher-elevation pine-oak and especially mixed-conifer forests, and a mixture of overstory heights in mid-elevation pine-oak forests. We recommend additional detailed studies of nesting habitat and the effects of disturbance processes on nesting habitat. Such studies will add to our understanding of the ecology of these 2 bird species and habitat conservation in this ecologically important area.
A lichen inventory of White Rocks Open Space (City of Boulder, CO), a unique outcropping of exposed unstable sandstones, is presented. White Rocks is an ecologically important, ∼40.5-ha (100-acre) protected area whose biological significance is in part attributable to geological and climatological history as well as degree of preservation, but also because it represents a biodiversity reservoir in a sea of agriculture and urban development. This inventory resulted in documentation of 56 species, including 1 new record to the United States, 1 new record to Colorado, 2 species new to science, and 2 additional species potentially new to science pending further study. Several species, though common at White Rocks, are locally rare within Boulder County and the Front Range Mountains of Colorado owing to a paucity of exposed sandstone. Such species instead have affinities to habitats more typical of eastern and far western Colorado, such as the state's high plains and sage-juniper scrub. A checklist of the 56 species is presented along with an assessment of taxon abundance and preliminary delimitation of 5 lichen communities. General discussion of ecology and management recommendations is provided. The present study is intended to begin the process of more fully documenting the lichen biota of Boulder City, Boulder County, and surrounding areas. Data herein also contribute new knowledge to the North American lichen biota as a whole via a comprehensive inventory of a sandstone formation, of which there exist relatively few. The inventory highlights the ecological significance of Open Space programs nationwide, particularly those in densely populated areas such as the Denver—Boulder—Longmont urban triangle. The discoveries reported here were made within a 10-min drive of the University of Colorado, demonstrating the potential for further discovery in Colorado lichenology.
Wilderness stream crossings used by mules, horses, and hikers are localized disturbances that may affect habitat immediately downstream, but the potential influence of fords on streams has received little investigation, particularly in terms of possible effects on fauna. Our overall null hypothesis was absence of below-above differences for either benthic macroinvertebrate assemblages or habitat characteristics at such fords. We further sought to determine (1) whether any such differences were present prior to annual use, suggesting longer-term effects, and (2) whether differences were present in late season, after annual use. We examined macroinvertebrates and habitat immediately below and above 2 fords crossing subalpine streams in Yosemite National Park in the Sierra Nevada (California, USA) in early and late season and over 2 years. There were both longer-term below-above differences, as well as differences that became apparent in late season, both of which were indicative of below-ford effects. Below fords there was evidence, either as main effects or interactions, of higher silt, sand, and gravel cover; a thicker periphyton layer; a greater Hilsenhoff biotic index; a higher proportion of tolerant taxa; higher chironomid midge and total densities; and greater species richness, largely a function of chironomid richness. There was also a lower expected number of species, a smaller proportion of sensitive taxa and predators, and lower densities of some sensitive Ephemeroptera (mayflies) and Plecoptera (stoneflies) below fords. Both hikers and stock may contribute to the apparent effects, but management interventions targeting stock may be particularly achievable. Among other approaches, simply halting stock strings briefly before reaching fords should reduce the volume of urine and feces directly entering streams, and handlers can expedite crossings if watering is not necessary.
The biogeographic history of aquatic organisms in relation to the Wasatch Mountains divide (which separates the eastern Great Basin and upper Colorado River basin in Utah) has been little studied aside from a large body of work on fishes. Pyrgulopsis kolobensis is a small springsnail that is distributed (in the eastern portion of its range) along the western flanks of the Wasatch Mountains, with a single population occurring just across the Wasatch divide in Strawberry Valley. Here we analyze the genetic structure of this species across the Wasatch divide (using the mtCOI gene) to discriminate between alternative hypotheses that explain this distributional pattern. The 6 P. kolobensis populations that we sampled were resolved as a single, weakly supported and shallowly structured clade in a Bayesian analysis. Specimens from Strawberry Valley shared a unique haplotype and differed from the other populations by 0.3%–0.8% sequence divergence, suggesting a geologically recent split that well postdated the Miocene inception of the Wasatch divide. This result is consistent with a hypothesis (supported by geological evidence) that the Strawberry Valley population became isolated during the late Quaternary as a result of a headwater transfer across the Wasatch divide. Our findings parallel a recent phylogeographic study of regional pebblesnails (Fluminicola coloradensis) and contrast with the prevailing pattern in fishes, which generally do not cross the Wasatch divide. The ability of these 2 snail species to penetrate into upland headwater habitats appears to be the key to their success in crossing the Wasatch (and other) drainage divides.
Cacti are transplanted when their occurrence conflicts with road and pipeline construction and mitigation requires relocation, or they are transplanted for personal use. Methods used in transplanting have credence by virtue of common practice; however, there are few scientific studies comparing different methods. Our objective was to determine if different transplanting techniques, time of year of transplanting, and association with a nurse plant upon transplanting affected the long-term survival (8 years) and vigor of Sclerocactus parviflorus (Clover and Jotter). The 3 transplanting procedures were as follows: (1) cacti excavated, soil removed from roots, roots trimmed, plants placed in shaded open environment for 2 days and then transplanted (modification of conventional procedure); (2) cacti excavated to maintain a root ball and transplanted within 2 hours; and (3) cacti excavated, soil shaken off the roots and transplanted within 2 hours. Mortality was documented every spring and fall for 8 years. Plant vigor was determined in the eighth year by measuring flower and tubercle production. There was no difference in cactus survival among the 3 transplanting techniques, time of year of transplanting, and association with a nurse plant. There was no difference in vigor among the treatments as measured by flower and tubercle production. Three years after transplanting, 97% of the cacti were alive, and after 8 years 84% were alive. Based on this study, transplanting of S. parviflorus with high long-term survival can be done by any of these procedures, at any time of year, and with or without an associated nurse plant.
Many carnivores are sensitive to habitat fragmentation, and the capacity to shift diets may improve their ability to persist in urban areas. We collected and identified contents of a total of 119 scats from coyotes (Canis latrans), 58 scats from gray foxes (Urocyon cinereoargenteus), and 31 scats from bobcats (Lynx rufus) within habitat fragments of varying size in the San Diego area in coastal southern California. Coyote diet was generalist, composed of mostly mammals but also anthropogenic items, fruit and seeds, birds, and invertebrates. Dietary breadth of coyotes was similar in small urban habitat fragments and larger sites, but composition differed, suggestive of the opportunistic habits of coyotes. Notably, domestic cats occurred in 29% of coyote scats in small urban fragments, implicating coyotes as a threat to cats. Like coyotes, gray foxes had an omnivorous diet consisting of mammals, fruit and seeds, invertebrates, and birds. As with coyotes, dietary breadth of gray foxes was similar in urban habitat remnants and larger control sites. Bobcats, not detected in small urban fragments, had a more specialized diet focused primarily on mammalian prey. Such resource specialization might limit bobcats' ability to exploit anthropogenic subsidies and hence persist in small urban patches, compared to more opportunistic carnivores such as coyotes and gray foxes.
Declines in Greater Sage-Grouse (Centrocercus urophasianus, hereafter sage-grouse) populations could be attributed to low chick survival, which may be influenced by the availability of food and cover at sites used by females rearing broods. Habitat attributes important to broods may vary regionally; thus, it is necessary to understand factors affecting regional sage-grouse brood-rearing site selection, especially when estimating the impacts of development. We monitored brood-rearing female sage-grouse equipped with solar Argos Global Positioning System Platform Transmitter Terminals from 2011 to 2013 to assess microhabitat selection by broods in Carbon County, Wyoming. We measured vegetation and arthropod characteristics at diurnal sites used by broods (n = 42 in 2011, n = 31 in 2012, n = 32 in 2013) and at 3 paired-random sites associated with each used site (n = 315), located 50 m, 250 m, and 500 m from the used site. We fit conditional logistic models within an information-theoretic framework to identify vegetation and arthropod characteristics associated with microsite selection of brood-rearing sites. Sage-grouse selected brood-rearing sites with greater visual obstruction (0–45.7 cm in height), higher numbers of arthropods in the order Diptera, and lower numbers of arthropods in the order Coleoptera. There was an interaction effect between the number of arthropods in the order Hymenoptera and the canopy cover of broad-leaf forbs; the relative probability of selection increased with increasing number of Hymenoptera when there was low cover (<20%) of broad-leaf forbs, but decreased with increasing number of Hymenoptera when there was high broad-leaf forb cover (>20%). We also found a quadratic relationship between selection of brood-rearing sites and total vegetation canopy cover; the relative probability of selection increased until approximately 75% cover and then decreased with increasing cover. Sage-grouse rearing broods selected a diverse array of vegetation types, but greatest use occurred within mesic communities. Our results could be used to identify vegetation communities with high relative probabilities of use by sage-grouse rearing broods, which will help guide management decisions and provide reference conditions for future research that evaluates the effects of wind energy development on sage-grouse.
The bark of quaking aspen (Populus tremuloides), a clonal hardwood that is dominant in many Rocky Mountain forests, varies from white to orange to green among both ramets and populations. The proximate causes of this color variation remain controversial. We collected 72 samples of aspen bark from 11 locations in Boulder County, Colorado, and used microscopy, dissection, and thin layer chromatography to assess the structural and biochemical basis for the color gradient. Our study shows that the cork cells closest to the cork cambium of the aspen were consistently orange and conglutinated. Outward from this layer, the cork cells transitioned from orange to white; they aged and simultaneously lost cohesion. Green bark was visible due to thinnest cork layers, which revealed subcortical chlorenchyma tissue, the only bark tissue in which photosynthetic pigments were detected. Tests for photosynthetic pigmentation in the cork were negative. Comparison to standards indicated that b-carotene is not the pigment responsible for the orange hue of the cambium. We conclude that the powdery substance found on the tree surface is composed of bark cells, and their color variation seen on the aspen bark is attributed to the cell's pigment content and thickness, although the molecule responsible for cork cell coloration remains unidentified.
Herein we present the first contemporary record of the jaguar (Panthera onca) in Morelos State and the Sierra de Huautla Biosphere Reserve. The record is based on 3 photographs of an adult jaguar obtained by photo-trapping. This noteworthy record extends the geographical distribution of the species into central Mexico by more than 100 km.
Little information is known about reproduction in the 3 species of shrews in Louisiana. We examined reproductive notes from specimen records for the southern short-tailed shrew (Blarina carolinensis), least shrew (Cryptotis parva), and southeastern shrew (Sorex longirostris). Most breeding activity occurred from March to December for B. carolinensis and C. parva. Average number of embryos was 3.75 for B. carolinensis and 5.5 for C. parva. The average length of testes was 5.2 mm for B. carolinensis and 3.8 mm for C. parva. One male S. longirostris possessed a testis length of 3 mm.
Based on the first record in the state of Morelos and a new record for the Estado de México, we suggest that Reithrodontomys microdon preferentially uses an arboreal habitat. Specimens described here, for the most part (75%), were captured >4 m above ground on trees. Although historical records indicate that R. microdon is rare, our data may suggest otherwise. Assuming this species is preferably arboreal and that most inventories of rodents have focused on the ground, it is evident that, historically, this species has not been surveyed in its preferred habitat.
Capture data differed at woodrat houses associated with selected microhabitats in a chaparral-oak woodland site in the foothills of northwestern California. Mean trapping success was significantly higher at houses located under dense tree canopy (and in low scrub cover) compared with houses in high scrub cover (and under less tree canopy), as was trapping success at houses found in non-edge versus edge habitat. Woodrats trapped at houses under dense canopy also were significantly heavier than those captured in high scrub cover; however, mean body masses at edge- and non-edge houses were similar. Broadly, our results mirror existing research but indicate the need for more study of the specific microhabitat factors that influence woodrat house use in chaparral-oak habitat.
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