Now showing items 8663-8682 of 20719

    • Habitat relationships of the pyrenean gray partridge

      Lescourret, F.; Génard, M. (Society for Range Management, 1993-07-01)
      Summer habitat relationships of the pyrenean gray partridge (Perdix peridix hispaniensis) were studied in the northern Pyrenees Mountains (France). Six available habitat types were defined, and those selected or avoided were identified. The only habitat type significantly (P < 0.05) selected was at intermediate altitudes, on fairly steep south-exposed slopes, with a moderate cover of woody plants. Two habitat types were significantly avoided. One occurred at low altitudes on mowed plateaus colonized by low woody plants, and the other was at high altitudes on slopes free of low woody plants. We suggest applications of the work in a model that should lead to valid habitat recommendations for restoring partridge populations.
    • Habitat Requirements of the Golden-Cheeked Warbler: Management Implications

      Kroll, J. C. (Society for Range Management, 1980-01-01)
      Characteristics of nesting and wintering habitats of golden-cheeked warblers (Dendroica chrysoparia) were studied from 1973-1978. Golden-cheeks are obligatively dependent on Ashe juniper (Juniperus ashei) for nesting materials and singing perches, but are equally dependent on scrub-oak (Quercus durandii breviloba) for foraging substrates. Golden-cheeks preferred to forage (73.6% of total observations) in hardwood species. Stepwise discriminant analysis suggested that quality nesting habitat differs from poor nesting habitat by having older (greater than or equal to 40 yrs.) Ashe juniper, lower juniper densities and higher densities of oak (juniper-oak ratio = 1.35 to 1). Structure of scrub-oak (mostly Q. oleoides) in the wintering habitat (La Esperanza, Intibuca Dept., Honduras) was structurally similar to that in the nesting habitat. Golden-cheeks were observed feeding in the shrubby understory.
    • Habitat Restoration--Solving the Puzzle of Wildlife Diversity in Texas

      Wagner, Matt; Pluhar, Jenny (Society for Range Management, 1996-06-01)
    • Habitat selection and activity patterns of female mule deer in the Front Range, Colorado

      Kufeld, R. C.; Bowden, D. C.; Schrupp, D. L. (Society for Range Management, 1988-11-01)
      Twenty-two adult, female mule deer (Odocoileus hemionus hemionus) were radio-collared with activity sensors and monitored with ground triangulation from mid-November through March, for 3 years (1982-1985) in the foothills west of Fort Collins, Colorado, to test 4 general hypotheses about habitat selection and activity: (1) The proportion of time deer spend feeding and resting varies with time of day. (2) Deer alter their activity patterns in response to environmental influences. (3) Selection of specific vegetation types for feeding and resting varies with time of day. (4) Ecotones are preferred habitats. Deer were monitored during 6-hr sampling periods: sunrise, daytime, sunset, and night. Deer fed most during sunset, night, and sunrise periods and least during the day. Feeding occupied similar proportions of an average deer's time during sunset, night, and sunrise periods. They preferred the grassland type for feeding and resting at night and the mountain mahogany (Cercocarpus montanus) type for both activities during all other periods. Preference deer showed for the ponderosa pine (Pinus ponderosa) type for feeding activity was inversely related to canopy cover. Deer rested most during daytime and night periods. During periods of daylight, deer using the grassland type showed preference for ecotones with certain types offering escape cover. No such preference was observed at night. Deer fed less and rested more when snow depth exceeded 36 cm. No significant differences (P>0.05) in the proportion of time deer devoted to feeding were found in the following comparisons: clear versus cloudy full-moon nights (-50 vs. + 50% cloud cover), full-moon versus new-moon, low versus high wind speeds (0-32 vs. 32-56 km/hr), and warm versus cold temperatures (+18 to -15 vs. -15 to -23 degrees C). No significant relationships were found for the same comparisons in proportion of time devoted to resting.
    • Habitat Selection and Vegetational Characteristics of Antelope Fawn Bedsites in West Texas

      Tucker, R. D.; Garner, G. W. (Society for Range Management, 1983-01-01)
      Vegetative composition, dominance, and height of cover characteristics were measured at 60 daytime bedsites of pronghorn antelope (Antilocapra americana) fawns in a desert grassland in southwest Texas. Fawns were fitted with radio transmitters and were located daily between 8 May and 9 July 1978. Igneous hill and mountain range sites were used 69% of the time during the first 4 weeks of age. Black grama (Bouteloua eriopoda), sideoats grama (B. curtipendula), hairy grama (B. hirsuta), and cane bluestem (Bothriochloa barbinodes) were the dominant species at bedsites of fawns 1 to 4 weeks of age. Cane bluestem and sideoats grama were the tallest species, averaging 52 and 42 cm in height, respectively. Blue grama (B. gracilis), tobosa grass (Hilaria mutica), and black grama were the species that occurred most often at bedsites of fawns 4 to 8 weeks of age. Cane bluestem, threeawns (Aristida spp.), sideoats grama, and tobosa grass had average heights of 46 cm, 38 cm, 41 cm, and 43 cm, respectively. Cover characteristics of the bedsites were taller than cover characteristics of the surrounding area (P<0.015) for fawns less than 4 weeks of age, but were the same for fawns over 4 weeks of age. Shrubs were not a major component of any bedsite. Management of areas used by fawns less than 4 weeks of age may be critical to young survival.
    • Habitat selection by cattle along an ephemeral channel

      Smith, M. A.; Rodgers, J. D.; Dodd, J. L.; Skinner, Q. D. (Society for Range Management, 1992-07-01)
      Because of widespread concern about cattle grazing effects on riparian zones of public lands, seasonal habitat selection by cattle was studied along a cold desert area ephemeral waterway of northcentral Wyoming. Little is known of grazing effects on ephemeral streams compared to perennial streams. Cattle activity was monitored in small pastures and a surrounding large allotment in spring, summer, and fall. Observations included activity and habitat where it occurred. Concomitantly, utilization levels, protein content, and dry matter content of forages were determined in the small pastures. A higher percent of cattle selected channel and floodplain habitats than percent area of habitats while a lower percent of cattle selected upland habitat than percent of this habitat in the area. Utilization levels of forages except greasewood (Sarcobatus vermiculatus (Hook.) Torrey) in the floodplain were not greatly different among habitats. Protein and dry matter content of forages did not vary greatly among habitats, except greasewood had higher protein and lower dry matter than other species and received much higher use. Forage quality declined in summer and fall. Animal preference for channel habitat was attributed to more available forage in the channels. In contrast, selection of floodplains was due to succulence and high protein content of greasewood. Comparison of cattle selectivity between small pastures and the large allotment indicates that greater avoidance of upland areas by cattle is likely due to greater distances to drinking water in the large allotment.
    • Habitat Selection by Cattle Along an Ephemeral Channel

      Smith, Michael A.; Rodgers, J. Daniel; Dodd, Jerrold L.; Skinner, Quentin D. (Society for Range Management, 1993-06-01)
    • Habitat Selection by Free-Ranging Bison in a Mixed Grazing System on Public Land

      Ranglack, D. H.; Du, Toit, J. T. (Society for Range Management, 2015-07)
      Domestic livestock have replaced bison (Bison bison) on almost all the remaining rangelands of North America. One of the few places where bison and cattle (Bos taurus) comingle on shared rangelands is in the Henry Mountains (HM) of southern Utah. Ranchers there are concerned, however, that bison are selecting the same grazing areas that are needed by cattle. We used global positioning system telemetry on bison across the entire HM rangeland to determine which habitats are most important for bison throughout the seasonal cycle. Sexual segregation was also measured (using the segregation coefficient, SC) to determine if bison bulls exert localized impacts by congregating in certain habitats separate from cow/calf groups. The HM bison exhibited low levels of sexual segregation for both the breeding (SC = 0.048) and nonbreeding seasons (SC = 0.112). We found bison habitat use to be diverse and dynamic, with bison grazing effects distributed widely across habitats throughout the seasonal cycle. Patches of grassland, whether naturally occurring or created through burning or mechanical treatments, were favored regardless of their distance to water. Our findings should assist ranchers and agency personnel in moving forward with the integrated management of free-ranging bison and cattle on the HM rangeland, with implications for bison conservation on public lands elsewhere in the United States. © 2015 The Authors.
    • Habitat selection patterns of feral horses in southcentral Wyoming

      Crane, K. K.; Smith, M. A.; Reynolds, D. (Society for Range Management, 1997-07-01)
      Feral horse habitat selection patterns and forage attributes on available habitats were studied on public rangelands of southcentral Wyoming. Environmental assessments preceding roundup of excess horses requires resource data to justify the number of horses removed. Randomly selected bands of horses were followed for 24-hour observation periods during the spring and summer to determine if they utilized habitats in proportion to their abundance. We also determined if forage abundance, succulence (an index to forage palatability), percent utilization, and dietary composition were related to habitats selected. Streamsides, bog/meadows, and mountain sagebrush habitats were preferentially selected (p less than or equal to 0.05). Lowland sagebrush habitats were avoided and no apparent selection behavior was shown for grassland and coniferous forest habitats. Forage abundance, palatability, and percent utilization were higher (p less than or equal to 0.05) in streamside and bog/meadow habitat classes. Diet composition indicated that sedges (Carex sp.), common in streamsides and bog/meadows, were an important forage of feral horses. Palatability and abundance of graminoid vegetation and proximity to preferred habitats seemed to be the primary influences on habitat selection by feral horses.
    • Habitat Selection, Foraging Behavior, and Dietary Nutrition of Elk in Burned Aspen Forest

      Canon, S. K.; Urness, P. J.; DeByle, N. V. (Society for Range Management, 1987-09-01)
      Prescribed burning is frequently used to enhance regeneration of aspen. The effects of burning aspen on wild ungulates are poorly understood. We used free-ranging tame elk to assess diet composition and quality on a site containing a 40-ha aspen burn, pure unburned aspen, mixtures of aspen and conifers, and other habitats. Foraging preferences of elk among the habitats were also investigated. Overall, no dietary nutritional differences were found between burned and unburned aspen habitats. Diet composition by forage class varied somewhat, due primarily to an abundance of very palatable post-fire forbs on the burn. Time spent feeding was significantly different among habitats. The burn was substantially more attractive for foraging probably because preferred forages were consistently available and greater foraging efficiency was possible than in other habitats.
    • Habitat Use and Fecal Analysis of Feral Burros (Equus asinus), Chemehuevi Mountains, California, 1974

      Woodward, S. L.; Ohmart, R. D. (Society for Range Management, 1976-11-01)
      Between January and March burros spent from 60 to 78.7% of their time on the interfluves. In April, habitat use was predominantly in washes, with a high of 58.5% in July. During the summer months, when daily maximum ambient temperature approached 48°C, much of their time was spent in densely shaded pockets of vegetation along the Colorado River. Thirty-nine plant species comprised the diet in 1974, desert Indian-wheat (Plantago insularis) and palo verde (Cercidium floridum) being the most common. These two species, combined with mesquite (Prosopis spp.) and arrowweed (Pluchea sericea) formed over 50% of the annual diet. The 1974 diet consisted of 3.9% grasses, 30.1% forbes, and 61.1% browse. Population increases of 20-25% every 13-18 months and little predation bespeaks the need for unceasing management and possible control to prevent deterioration of the native flora and fauna.
    • Habitat Use by Federal Horses in the Northern Sagebrush Steppe

      Ganskopp, D.; Vavra, M. (Society for Range Management, 1986-05-01)
      Distribution patterns of feral horses (Equus caballus) relative to plant communities, herbaceous production, and perennial water sources were studied from April 1979 to March 1981 in Oregon's Owyhee Breaks. Repeated observations of radio-collared and easily identified horses allowed estimation of home range sizes and documentation of the plant communities utilized. A map of plant communities was constructed, and composition and herbaceous production of key communities sampled. Time-lapse cameras monitored the daylight watering patterns of horses. One hundred thirty-three horses were initially censused and identified on the study area with the total population subsequently increasing at an annual rate of 13%. Home ranges averaged 12 km2 with the minimum convex polygon procedure and 27 km2 with the 90% confidence ellipse method. No seasonal shifts in home ranges occurred, and no correlations were detected between home range size and number of horses per band, densities of perennial water sources, or levels of forage production within home ranges. Six distinct herds were identified on the area. Only one band of horses moved from one herd to another during the 2-year study. Animals in each herd made greatest use of the most prevalent plant community, with no community being universally preferred to over another. Watering activities were most intense during the first and last periods of daylight. Horses rapidly vacated the watering areas after drinking. A seasonal trend was observed in which horses remained slightly closer to perennial water sources during warm, dry summer months than during spring periods when additional seasonal sources were available. Seasonal differences were not statistically significant, however.
    • Habitat use by white-tailed deer on cross timbers rangeland following brush management

      Leslie, D. M.; Soper, R. B.; Lochmiller, R. L.; Engle, D. M. (Society for Range Management, 1996-09-01)
      Seasonal habitat use by white-tailed deer (Odocoileus virginianus Zimmerman) was monitored with radio telemetry in 1988-89 to determine responses to experimental brush treatments, 5-6 years post-treatment, in the cross timbers region of central Oklahoma. The study area was a mosaic of brush treatments: tebuthiuron (N-[5-(1,1-dimethylethyl)-1,3,4-thiazol-2-yl 1]-N,N'-dimethylurea) herbicide, tebuthiuron with an annual spring burn, triclopyr ([(3,5,6-trichlor-2-pyridinyl)oxy]acetic acid) herbicide, triclopyr with an annual spring burn, and no herbicide with annual spring burning. Control areas with no burning or herbicide applications also were evaluated. Herbicides were applied in 1983, and fires were initiated in 1985. Annual home range (95% harmonic mean) averaged 99.9 ha, and no differences in size among seasons or between sexes were observed. Both sexes selected and avoided specific brush treatments throughout the year. Female deer selected or avoided more human-altered habitats in specific contrasts of main treatment groups (e.g., treated vs. control, herbicide vs. no herbicide, fire vs. no fire, etc.) than males. Both sexes selected fire treatments in summer and were most particular in their choice of main treatment groups in summer and fall habitat use between the sexes was most similar in winter and most disparate in fall. The mosaic of habitat types resulting from the variable herbicide and burn application pattern probably influenced deer habitat use in the cross timbers region through combined effects of increased mid-story cover and forage production as they relate to reproductive activities and nutritional needs of female deer in particular.
    • Habitat Use of Feral Horses and Cattle in Wyoming’s Red Desert

      Miller, R. (Society for Range Management, 1983-03-01)
      Habitat selection by feral horses (Equus caballus) and cattle (Bos taurus) was studied with a series of 16 flights, between November 1977 and April 1979, during which the locations of cattle and feral horses were mapped. The C7 coefficient of association and percent occurrence in different vegetation types and near water sources and ridges were used to compare and describe the habitat use patterns. Cattle and feral horses showed seasonal patterns relative to vegetation types and distance from water sources, and horses showed a seasonal use pattern in regard to areas near ridges. Possibilities for direct competition between cattle and feral horses in the Red Desert were strongest for forage during the fall and in severe winters, and for water during the summer.
    • Habitat-Type: A Review

      Dyksterhuls, E. J. (Society for Range Management, 1983-12-01)
    • Hacking the Electorate: A Non-Intervention Violation Maybe, but Not an Act of War [Article]

      Stein, Christopher T. (The University of Arizona James E. Rogers College of Law (Tucson, AZ), 2020)
    • Half Full or Half Empty?

      McGinley, Susan (College of Agriculture, University of Arizona (Tucson, AZ), 1993)
    • Half-Century Changes on Northern Nevada Ranges

      Robertson, J. H.; Kennedy, P. B. (Society for Range Management, 1954-05-01)
    • Half-Life Determination of 41Ca and Some Other Radioisotopes

      Kutschera, Walter; Ahmad, Irshad; Paul, Michael (Department of Geosciences, The University of Arizona, 1992-01-01)
      We have performed a new determination of the half-life of 41Ca by measuring the specific activity of an enriched Ca material with known 41Ca abundance. We measured the activity via the 3.3-keV X-rays emitted in the electron capture decay of 41Ca, and the 41Ca abundance was measured by low-energy mass spectrometry. The result, t1/2 = (1.01 +/- 0.10) x 10^5yr, agrees with the recent 'geological' half-life of Klein et al., (1991), t1/2 = (1.03 +/- 0.07) x 10^5 yr, and with the corrected value of Mabuchi et al. (1974), t1/2 = (1.13 +/- 0.12) x 10^5yr. We recommend the weighted mean of these three measurements, t1/2 = (1.04 +/- 0.05) x 10^5yr, as the most probable half-life of 41Ca. We also discuss the situation of the radioisotopes, 32Si, 44Ti, 79Se and 126Sn, whose half-lives, though still uncertain, are potentially interesting for future AMS studies and other applications.
    • Halite and stable chlorine isotopes in the Zag H3-6 breccia

      Bridges, J. C.; Banks, D. A.; Smith, M.; Grady, M. M. (The Meteoritical Society, 2004-01-01)
      Zag is an H36 chondrite regolith breccia within which we have studied 14 halite grains less than or equal to 3 micrometers. The purity of the associated NaCl-H2O brine is implied by freezing characteristics of fluid inclusions in the halite and EPMA analyses together with a lack of other evaporite-like phases in the Zag H36 component. This is inconsistent with multi-stage evolution of the fluid involving scavenging of cations in the Zag region of the parent body. We suggest that the halite grains are clastic and did not crystallize in situ. Halite and water-soluble extracts from Zag have light Cl isotopic compositions, delta-37Cl = 1.4 to 2.8 ppm. Previously reported bulk carbonaceous chondrite values are approximately delta-37Cl = +3 to +4 ppm. This difference is too great to be the result of fractionation during evaporation, and instead, we suggest that Cl isotopes in chondrites are fractionated between a light reservoir associated with fluids and a heavier reservoir associated with higher temperature phases such as phosphates and silicates. Extraterrestrial carbon released at 600 degrees C from the H34 matrix has delta-13C = -20 ppm, consistent with poorly graphitized material being introduced into the matrix rather than indigenous carbonate derived from a brine. We have also examined 28 other H chondrite falls to ascertain how widespread halite or evaporite-like mineral assemblages are in ordinary chondrites.