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Wildlife managers in northwestern Colorado have had difficulty accurately estimating numbers of subadult male elk (Cervus elaphus) by sampling winter population densities and sex ratios. We investigated emigration and survival of telemetered 2-year-old male elk in a trophy hunting area in a northwestern Colorado Game Management Unit (GMU) to evaluate management strategies. We hypothesized that skewed numbers of males resulted from high subadult mortality or dispersal of subadult males. We used telemetered elk and Kaplan-Meier staggered entry methods to estimate emigration probability of 0.56 and 0.33 in 1995 and 1996, respectively. Maximum distances moved by emigrants from their capture point averaged 87 km (median...
Bryophytes disperse by small unicellular spores between 7 ?m und usually less than 100 ?m. A large percentage of species is sterile and propagates vegetatively either by special brood bodies or fragments of whole plants. It is shown that there is no difference in the effectiveness between generative and vegetative propagation. Size and weight of the diaspores suggest that both must easily be dispersed and the species must therefore have wide ranges. This does, however, not result in ubiquitous occurrence. This is only true for part of the species. Many, even sterile species show wide transcontinental ranges. On the other hand, there are many examples of limited to very limited distribution in spite of a rich production...
The present distribution of the Mexican vole (Microtus mexicanus) is not entirely the product of post-Pleistocene forest fragmentation and extinction; recent dispersal also is indicated. Literature records further suggest that this phenomenon may reflect a general pattern of northward range expansion in many southwestern mammal species. Published in Western North American Naturalist, volume 52, issue 3, in 1992.
The rate of future climate change is likely to exceed the migration rates of most plant species. The replacement of dominant species by locally rare species may require decades, and extinctions may occur when plant species cannot migrate fast enough to escape the consequences of climate change. Such lags may impair ecosystem services, such as carbon sequestration and clean water production. Thus, to assess global change, simulation of plant migration and local vegetation change by dynamic global vegetation models (DGVMs) is critical, yet fraught with challenges. Global vegetation models cannot simulate all species, necessitating their aggregation into plant functional types (PFTs). Yet most PFTs encompass the full...
Using a variety of sampling techniques and observations we describe aspects of the reproductive ecology and early life-history of Bear Lake sculpin, Cottus extensus, a species endemic to Bear Lake, Utah-Idaho. Adult sculpin spawned in shallow water (0.5-6.0 m depths) in cavities beneath large cobbles and boulders. During 1993, egg mass densities were highest (> 4.0 m(2)) at 1.0-2.0 m depths. Electivity indices verified substrate selection and also indicated an avoidance of sand- and gravel-embedded materials. During years of low water elevation, suitable spawning substrates were restricted to one Or two limited areas of the lake and comprised < 0.004% of the total benthic area. Disturbance from turbulence, as would...
Translocations of greater sage-grouse (Centrocercus urophasianus) have been attempted in 7 states and one Canadian province with very little success. To recover a small remnant population and test the efficacy of sage-grouse translocations, we captured and transported 137 adult female sage-grouse from 2 source populations to a release site in Strawberry Valley, Utah, USA, during March-April 2003-2005. The resident population of sage-grouse in Strawberry Valey was approximately 150 breeding birds prior to the release. We radiomarked each female and documented survival, movements, reproductive effort, flocking with resident grouse, and lek attendance. We used Program MARK to calculate annual survival of translocated...
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Symphyotrichum expansum (Puepp ex Spreng.) Nesom is reported new to Utah from the Escalante River drainage. A major range extension is reported for Aralia racemosa L. in the Escalante drainage, and additional populations are reported of the rare species Imperata brevifolia Vasey in Utah, including the 1st record for the Grand Staircase--Escalante National Monument. Heterotheca grandiflora Nutt. is reported new to north central Arizona. New locations and notes on an additional 22 rare species in Glen Canyon National Recreation Area are listed. Published in Western North American Naturalist, volume 65, issue 1, on pages 103 - 111, in 2005.
Landscape features such as mountains, rivers, and ecological gradients may strongly affect patterns of dispersal and gene flow among populations and thereby shape population dynamics and evolutionary trajectories. The landscape may have a particularly strong effect on patterns of dispersal and gene flow in amphibians because amphibians are thought to have poor dispersal abilities. We examined genetic variation at six microsatellite loci in Columbia spotted frogs (Rana luteiventris) from 28 breeding ponds in western Montana and Idaho, USA, in order to investigate the effects of landscape structure on patterns of gene flow. We were particularly interested in addressing three questions: (i) do ridges act as barriers...
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I examined dispersal and social organization of Gunnison's prairie dogs (Cynomys gunnisoni) for 7 years at Petrified Forest National Park, Arizona. Within colonies, individuals lived in harem-polygynous family groups called clans. The number of clans at the study site each year ranged from 21 to 23, with a mean of 22.3. Clan size (the number of adults living in the same territory) ranged from I to 19, with a mean of 5.30. Clans contained 1.06 +/- 0.39 (SD) breeding males,, 3.01 +/- 2.08 breeding females, and 1.23 +/- 1.65 nonbreeding yearling males. Some clams contained two breeding males, and others contained no resident breeding male. The area of clan territories ranged from 0.16 ha to 1.82 ha, with a mean of...
Wind is suspected to be a primary dispersal mechanism for large branchiopod cysts on the Colorado Plateau. We used a wind tunnel to investigate wind velocities capable of moving pothole sediment and cysts from intact and disturbed surfaces. Material moved in the wind tunnel was trapped in filters; cysts were separated from sediment and counted. Undisturbed sediment moved at velocities as low as 5.9 m s?1 (12.3 miles h?1). A single all-terrain vehicle (ATV) track increased the sediment mass collected 10-fold, with particles moving at a wind velocity of only 4.2 m s?1 (8.7 miles h?1). Cysts were recovered from every wind tunnel trial. Measured wind velocities are representative of low-wind speeds measured near Moab,...
A two-dimensional hydrodynamic model was applied to seven study reaches in the Colorado River within Grand Canyon to examine how operation of Glen Canyon Dam has affected availability of suitable shoreline habitat and dispersal of juvenile humpback chub (Gila cypha). Suitable shoreline habitat typically declined with increasing discharges above 226?425m3/ s, although the response varied among modelled reaches and was strongly dependent on local morphology. The area of suitable shoreline habitat over cover types that are preferred by juvenile humpback chub, however, stayed constant, and in some reaches, actually increased with discharge. In general, changes in discharge caused by impoundment tended to decrease availability...
Effective wildlife conservation strategies require an understanding of how fluctuating environmental conditions affect sensitive life stages. As part of a long-term study, we examined post-fledging and post-independence survival of 89 radio-marked juvenile Northern Goshawks (Accipiter gentilis) produced from 48 nests in northern Arizona, USA, during 1998-2001. Information-theoretic methods were used to examine within- and among-year variation in survival relative to environmental (prey abundance, weather), territory (hatching date, brood size), and individual (gender, body mass) sources of variation. The results support age- and cohort-specific differences in survival that were best explained by behaviors occurring...
Multiple factors likely influence natal dispersal behavior of juvenile mammals, which is typically male-biased. Because of their small body size and specific habitat requirements, pygmy rabbits (Brachylagus idahoensis) are expected to exhibit limited dispersal. We predicted that dispersal would be male-biased, that juveniles born later in the year would disperse farther, and that juveniles would be more likely to disperse away from areas of higher habitat saturation. We used radiotelemetry to study dispersal of 61 juvenile pygmy rabbits (31 males and 30 females) from shortly after emergence from natal burrows (April?July) to the beginning of the next breeding season (mid-March) during 2004?2006. Juveniles dispersed...
In this paper, we develop a five-step approach for analysis of historical relationships among areas of endemism using a set of 22 clades (9 mammal, 7 bird, 4 reptile, 1 amphibian, and 1 cactus) drawn from the warm deserts biota of western North America. As has been suggested in previous studies of portions of this biota, our results suggest a complex biogeographic history, but with substantial support for the influence of several major vicariant events in the diversification and assembly of the aridlands biota. We discuss and demonstrate the reciprocal strengths (and weaknesses) of phylogeography and phylogenetic biogeography for defining areas of endemism, analysing vicariance and dispersal, and dealing with temporal...
A small numbers of Ospreys (Pandion haliaetus) are known to have nested historically in Utah. A precise baseline figure is unavailable, but the 19th-century Osprey population in Utah probably consisted of at least 15 breeding pairs scattered in 4 geographic regions. Human persecution is believed to have caused the abandonment of nesting territories along the Wasatch Front and in the western Uinta Mountains by 1900 and 1960, respectively. Osprey populations in the southern plateaus and Green River areas, however, began increasing in the late 1970s. Several recent nesting attempts and numerous summer sightings at nontraditional and abandoned historical sites in Utah suggest the Osprey is also expanding its range in...
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Ephemeral aquatic habitats in Wupatki National Monument vary from naturally formed pools in arroyos over 5000 years old, to constructed catchment basins with ages estimated at 60?1000+ years old, and borrow pits and stock ponds 30?60 years old. The different ages of these pools provide different histories of colonization by amphibians and aquatic invertebrates, especially temporary pool specialists such as spadefoot toads and branchiopod crustaceans. Ten pools of five different origins and ages were surveyed in August and/or September 1997 for aquatic organisms; a total of 13 surveys were conducted. Twenty-two taxa were found, with the number of species in a pool during any survey ranging from one to 10. Species...
    map background search result map search result map Survey of aquatic macroinvertebrates and amphibians at Wupatki National Monument, Arizona, USA: An evaluation of selected factors affecting species richness in ephemeral pools Philopatry, Dispersal, and Social Organization of Gunnison's Prairie Dogs Notes on significant collections and additions to the flora of Glen Canyon National Recreation Area, Utah and Arizona, between 1992 and 2004 Survey of aquatic macroinvertebrates and amphibians at Wupatki National Monument, Arizona, USA: An evaluation of selected factors affecting species richness in ephemeral pools Philopatry, Dispersal, and Social Organization of Gunnison's Prairie Dogs Notes on significant collections and additions to the flora of Glen Canyon National Recreation Area, Utah and Arizona, between 1992 and 2004