Experimental manipulations of precipitation seasonality: effects on oak ( Quercus ) seedling demography and physiology

Predicted changes in regional precipitation patterns and soil moisture caused by anthropogenic trace gas emissions may affect the distribution and abundance of woody plants in arid and semiarid regions. To test the response of woody plants to potential changes in precipitation regimes, we manipulated summer and winter precipitation on plots that contained seedlings of Quercus emoryi Torr. (Emory oak), the dominant tree in oak savannas of the southwestern United States. Throughout the growing season, we monitored seedling survival and physiology (predawn leaf water potential, midday instantaneous gas exchange, and leaf carbon isotope discrimination). Seedling survival and physiological performance differed little between treatments, which embodied 50% changes to quantities of summer and winter precipitation, and encompassed a continuum of precipitation from 359 mm · year -1 to 846 mm · year -1 . However, survival and physiological performance of seedlings were negatively impacted by seasonal environmental conditions common to all treatments, especially during the annual pre-'monsoon' drought. Seedling predawn leaf water potentials, net CO 2 assimilation, and stomatal conductance indicate that growing conditions for Q. emoryi seedlings at this site are generally restricted to periods with adequate soil moisture (i.e., April and August). Results contrast with an assumption implicit to the ""two-layer"" soil water resource partitioning hypothesis that woody plants in all life history stages are more dependent upon winter than summer precipitation. In fact, summer precipitation appears more important than winter precipitation for Q. emoryi seedling recruitment and growth.     

Field observations of Irbisia pacifica (Hemiptera: Miridae): feeding behavior and effects on host plant growth

The interaction between a grass-feeding mirid, Irbisia pacifica (Uhler), and plant growth of intermediate wheatgrass, Thinopyrum intermedium (Host) Barkw. & D. R. Dewey, was examined on a field site in northern Utah in 1985. With egg hatch beginning in April, the bug completed its life cycle within two months. Ovarian development was completed by 11 June, a week after all bugs had become adults. The proportion of feeding damage per leaf (35.1%) peaked on the seventh week of the twelve-week study (18 July). Green leaf area per tiller decreased initially from bug feeding and then continued to decrease because of seasonal aging. All plants senesced within three months. Grass bugs predominantly attacked the second and third youngest leaves. Analyses of age-specific leaf cohorts demonstrated that the major effect of bug feeding was the loss of green leaf area and potential foliage production over time. Bug feeding may also exacerbate other physiological stresses on the host plants.     

The short song of Brewer's Sparrow: individual and geographic variation in southern Idaho

Brewer's Sparrows ( Spizella breweri ) have two song types--a ""short"" song that has 1 to 3 trill types and a ""long"" song that has 5 to 10 or more trill types. I describe the short song and examine patterns of individual and geographic song variation from 15 sites on the Snake River Plain in southern Idaho. Territorial males sang the short song regularly during the breeding season. Two-trill song types comprised 72.9% of all song types, with 3-trill types (18.8%) and 1-trill types (8.2%) less frequent. Over 90% of the males sang their song type(s) essentially without variation. Many trill types appeared most often in only 1 of 3 possible song positions, i.e., 1st, 2nd, or 3rd trill. Trill types that occurred in different song positions differed in syllables per second, trill and syllable duration, and frequency variables. First trill types were more variable than 2nd or 3rd trill types. There was no evidence that birds at sites closer together shared more trill types or pairs of trill types than those farther apart. There was no tendency for territorial neighbors to sing similar song types. Brewer's Sparrows' small territories, dense populations, and apparently high rate of annual turnover may mediate against the evolution of song sharing or vocal dialects.     

Habitat use and food selection of small mammals near a sagebrush/crested wheatgrass interface in southeastern Idaho

Habitat use and food selection data were collected for deer mice ( Peromyscus maniculatus ), montane voles ( Microtus montanus ), Ord's kangaroo rats ( Dipodomys ordii ), and Townsend's ground squirrels ( Spermophilus townsendii ) near a sagebrush ( Artemisia tridentata )/crested wheatgrass ( Agropyron cristatum ) interface in southeastem Idaho. Significantly more captures occurred in the native sagebrush habitat than in areas planted in crested wheatgrass or in disturbed sites. Crested wheatgrass, a prolific seed producer, still accounted for over 30% of the total captures. Montane voles and Townsend's ground squirrels (during periods of aboveground activity) used the crested wheatgrass habitat throughout the summer, while deer mice and, Ord's kangaroo rats exhibited heavy use after seed set.     

Role of post-Pleistocene dispersal in determining the modern distribution of Abert's squirrel

Abert's squirrel is a forest-dwelling mammal, dependent upon ponderosa pine, that now ranges from southern Wyoming to northern Mexico. During the late Pleistocene, ponderosa pine and this squirrel occurred no further north than central Arizona and New Mexico. In consequence, the present range of the squirrel north of the 36thparallel must have been the result of post-Pleistocene (Holocene) dispersal. If such dispersal took place after the fragmentation of the northern montane conifer forest, at least some leakage across barriers of unsuitable (non-ponderosa pine) habitat must have occurred. Dispersal following transplanting "experiments" has shown that such barriers can be crossed; other evidence is provided that suggests this may occur sufficiently often to produce significant changes in distribution within short periods of time. Thus, explanations for the distribution of Abert's squirrel, based only on historical legacy and local extinctions, are found to be insufficient. An alternative explanation is proposed in which post-Pleistocene dispersal also plays an important role.     

Late fall and early spring bird observations for Mulegé, Baja California Sur, Mexico

Observational data from spring and fall 1996 and spring 1997 for the region near Mulegé, Baja California Sur, Mexico, are summarized in tabular form. In addition, new or noteworthy data for 17 species are annotated to provide clarification of previously published records. A uniquely plumaged bird, too far south for a female American Robin ( Turdus migratorius ) in basic plumage and too far north for the endemic ""San Lucas"" Robin ( Turdus migratorius confinis ) and intermediate in coloration between the two, was recorded. Range expansions are documented for several species including the European Starling ( Sturnus vulgaris ), Anna's Hummingbird ( Calypte anna ), Western Meadowlark ( Sturnella neglecta ), White-faced Ibis ( Plegadis chichi ), and White-fronted Goose ( Anser albifrons ). Lease Grebes ( Tachybaptus dominicus ), a species of concern which is apparently declining in numbers, and Belding's Yellowthroat ( Geothlypis beldingi ) a species endemic to Baja California Sur, were observed in the freshwater marsh during all 3 study periods.     

The authorship and date of publication of Siren intermedia (Amphibia: Caudata)

However "just" it might be to credit LeConte, 1828, with Siren intermedia, both Harlan, 1826 (not 1827 as often cited), and Barnes, 1826, antedate LeConte's proposal of the name. As the earliest, Barnes, 1826, stands credited with it. In analysis of precedent for these conclusions, types of taxonomic plagiarism (calculated vs. innocent, homoplagiarism vs. heteroplagiarism) and the distinctions between nomina nuda and nomina dubia are reviewed, giving examples of each category.     

Radio transmitter attachment for chukars

Thirty-seven chukars ( Alectoris chukar ), fitted with conventional poncho-type radio transmitters, were released on Antelope Island in Utah's Great Salt Lake. Twenty-seven removed their radios, averaging three days after release. The remaining 10 died from predation (average 15 days). Twenty-two chukars with pleated and six with harness ponchos were then released. Five of the pleated ponchos were removed (average four days), and 17 resulted in mortality (average two days). All six harness poncho-equipped birds were dead the following day. A consequential laboratory study comparing various attachment methods (conventional, pleated, harness, and ""irreversible"" flange poncho vs. bellystrap and wingstrap backpack) favored the wingstrap backpack. The effectiveness of 30 conventional ponchos and 30 wingstrap backpacks was compared on game farm chukars. Twenty-nine removed their ponchos within one day. One remained attached throughout the 30-day trial. All of the wingstrap backpacks remained attached with no apparent problems.     

Pronghorn responses to hunting coyotes

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Six accounts of pronghorn antelope ( Antilocapra americana ) chasing or attacking coyotes ( Canis latrans ) are described: three chases by individual pronghorn does, two by herds of antelope, and one joint effort by a pronghorn doe and a Short-eared Owl ( Asio flammeus ). Modifications of Berger's (1979) ungulate antipredatory defense model are proposed.       

Notes on the Swainson's Hawk in central Utah: insectivory, premigratory aggregations, and kleptoparasitism

A premigratory flock of Swainson's Hawks numbering at least 213 individuals was observed during July and August of 1984. Aerial feeding on grasshoppers was noted and kleptoparasitism was recorded between the Swainson's Hawk and the American Kestrel.     

Winter crude protein among accessions of fourwing saltbush grown in a uniform garden

Winter crude protein content was determined for the current year's growth of 43 accessions of fourwing saltbush ( Atriplex canescens ) grown on a uniform garden. The crude protein level varied among accessions from 6 percent to 14 percent of dry matter. Individual plants (215) ranged from 5.3 percent to 17.1 percent. The mean winter crude protein level was 9.6 percent. Because these data were generated on even-aged plants, it appears that genetic variation plays an important role in determining the level of crude protein in fourwing saltbush.     

Environmental site characteristics and incidence of chokecherry black knot in Utah

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Black knot disease of chokecherries, induced by Dibotryon morbosum (Schw.) Th. & Syd., is widely distributed in Utah. The incidence of black knot was measured by determining the ratio of total black knot gall length to total stem length of plants and then expressing that value as a percentage of diseased stems in the sample plot. The environmental site factors measured were elevation, exposure, slope, soil pH, soil depth, distance to surface water, plant moisture stress, and associated vegetation. Numerical values were determined for each of these variables at each of 18 randomly located plots. Correlation coefficients for plant moisture stress and soil temperature were –.439 (p = .065) and –.440 (p = .055). Multiple regression analyses using plant moisture stress and soil temperature gave a regression coefficient of –.641 (p = .05). As plant moisture stress and soil temperature decreased, incidence of black knot increased.        

Influence of black-tailed prairie dog towns ( Cynomys ludovicianus ) on carnivore distributions in the Oklahoma Pandhandle

Carnivores were recorded at prairie dog towns and non-prairie dog town paired sites in the Oklahoma Panhandle over 4 sampling sessions from October 1995 to February 1997. We established carnivore presence through the use of baited tracking plates dusted with chalk and matched with infrared-triggered cameras. Five carnivore species were recorded at both prairie dog towns and paired sites across the Oklahoma Panhandle. Of these, 4 were recorded with sufficient regularity to permit analyses. Carnivores were analyzed at prairie dog towns across the entire Panhandle and in the Panhandle's westernmost county (Cimarron County) only. Canids showed no significant preference for prairie dog towns or other areas. In the Oklahoma Panhandle and Cimarron County only, occurrence of swift fox ( Vulpes velox ) between prairie dog towns and control sites was insignificant. Badgers ( Taxidea taxus ) and spotted skunks ( Spilogale putorius ) occurred significantly more often at prairie dog towns in Cimarron County but not in the Panhandle. No single mustelid species showed a significant association with either prairie dog towns or non-prairie dog town habitats. Our results indicate that whereas prairie dog towns do attract some carnivore species, the presumption that prairie dogs are ""keystone species"" for so many organisms (especially threatened or endangered species) in the current plains ecosystem may not be as clear as previously thought.     

Cattail decline at Farmington Bay Waterfowl Management Area

For the last seven years, 1969 to 1976, a steady decline of cattails ( Typha latifolia L.) has been observed at Farmington Bay Waterfowl Management Area, Davis County, Utah. Several parameters of Farmington Bay's environment that could cause or enhance a decline of the marshland vegetation were studied. These parameters included temperature, pH, phenols, oil and grease, heavy metals, fungus pathogens, and salt water intrusion from the Great Salt Lake. Elevated soluble salt concentrations were found to be responsible for the decline. Cattails are weakened or killed when they are exposed to soluble salt concentrations greater than 5.0 gm/liter, and there is a significant (1 percent level) negative correlation ( - 0.68) between soluble salt concentration and cattail height. Symptoms of elevated salt concentrations include stunted growth, leaf tip necrosis (burning), and occasional browning of an entire cattail clone. Furthermore, those salt concentrations that cause physiological stress in cattails also facilitate the growth of a decomposition fungus, Chaetophoma confluens. This fungus causes a rot consisting of irregularly scattered lesions on the surface of the rhizomes and was consistently isolated from rhizomes of declining plants.       

Planting depth of 'Hobble Creek' mountain big sagebrush seed

We conducted a greenhouse study in which 'Hobble Creek' mountain big sagebrush ( Artemisia tridentata ssp. vaseyana ) seeds were planted at various depths in soil to determine the optimal planting depth. Results showed that the optimal planting depth is 5 mm or less.     

Classification of the riparian vegetation along a 6-km reach of the Animas River, southwestern Colorado

Riparian ecosystems are important components of landscapes, particularly because of their role in biodiversity. A first step in using a ""coarse-filter"" approach to riparian biodiversity conservation is to determine the kinds of riparian ecosystems. These ecosystems vary substantially in plant species composition along a single river reach, as well as between rivers, and yet the river-reach scale has received little attention. We sampled the vascular plant composition of 67 contiguous patches of riparian vegetation along the reach of the Animas River, in southwestern Colorado's San Juan Mountains, that is relatively undisturbed by human land uses. Using cluster analysis and detrended correspondence analysis, we identified eight riparian community types along the reach. Using a new technique, we combined overstory size-class data and understory cover data to identify community types. The eight community types, which are in part the products of past floods, are spatially arranged along the reach in relation to variation in valley morphology, tributary location, and geomorphic landforms. These eight community types do not necessarily represent successional stages of a single potential vegetation type. This study at the river-reach scale suggests that sampling and analysis, as well as conservation, may need to be turned to the scale of patchiness produced by flood disturbances in the riverine landscape, since vegetation varies significantly at this scale.     

Nutritional condition of elk in Rocky Mountain National Park

We tested the hypothesis that elk in Rocky Mountain National Park (RMNP) were at ecological carrying capacity by determining herd-specific levels of nutritional condition and fecundity. Ingesta-free body fat levels in adult cows that were lactating were 10.6% ( s = 1.7; range = 6.2-15.4) and 7.7% ( s = 0.5; range = 5.9-10.1) in November 2001 for the Horseshoe and Moraine Park herds, respectively. Cows that were not lactating were able to accrue significantly more body fat: 14.0% ( s = 1.1; range = 7.7-19.3) and 11.5% ( s = 0.8; range = 8.6-15.1) for the Horseshoe and Moraine Park herds, respectively. Cow elk lost most of their body fat over winter (April 2002 levels were 3.9% [ s = 0.4] and 2.9% [ s = 0.4] for the Horseshoe and Moraine Park herds, respectively). Nutritional condition indicated that both Horseshoe Park and Moraine Park elk were well below condition levels elk can achieve on very good-excellent nutrition (i.e., > 15% body fat; Cook et al. 2004) and were comparable to other free-ranging elk populations. However, condition levels were higher than those expected at a ""food-limited"" carrying capacity, and a proportion of elk in each herd were able to achieve condition levels indicative of very good-excellent nutrition. Elk in RMNP are likely regulated and/or limited by a complex combination of density-independent (including significant heterogeneity in forage conditions across RMNP's landscape) and density-dependent processes, as condition levels contradict a simple density-dependent model of a population at ecological carrying capacity.     

Diet switching and food delivery by shrubsteppe passerines in response to an experimental reduction in food

We experimentally reduced the food base of nesting Brewer's Sparrows ( Spizella breweri ) and Sage Thrashers ( Oreoscoptes montanus ) in a shrubsteppe region of south central Idaho in 1989 and 1990. Frequency and mass of "birdfood" arthropods in pitfall, sweep net, and stickyboard samples were generally lower on sites treated with a broad-spectrum insecticide (malathion) than on untreated sites though the effect varied among taxa. In 1990 O. montanus switched nestling diets to prey taxa not affected by the treatment. Time between nestling food deliveries was greater for S. breweri on the treated than untreated site in 1989. In 1990 there were no between-site differences, but there was an increase in delivery time on the treated plot after treatment; this difference was within the range of delivery times recorded on the untreated plot. Malathion applications did reduce the food base, but plasticity in passerine behavior and emergence characteristics of some prey taxa ameliorated indirect effects of food reduction to birds.     

A survey and assessment of the rare vascular plants of the Idaho National Engineering Laboratory site

A two-year study of the rare vascular plants of the Idaho National Engineering Laboratory generated new data on the abundance, distribution, and habitat features of eight taxa presently under review at either the federal or state level, or recently proposed for such review. Astragalus ceramicus Sheld. var. apus Barneby is common on the INEL and adjacent areas and will be recommended for removal from further consideration at the federal level and placed on Idaho's Federal Watch List. Coryphanta missouriensis (Sweet) Britt. & Rose is common throughout east central Idaho, but will be recommended for retainment on the State Watch List. Gymnosteris nudicaulis (H. & A.) Greene and Oxytheca dendroidea Nutt. are also recommended for retention on the State Watch List. Four taxa not previously known to occur in Idaho or not known from the southeastern part of the state ( Astragalus gilviflorus Sheld., Astragalus kentrophyta Gray var. jessiae (Peck) Barneby, Gilia polycladon Torr., and Lesquerella kingii S. Wats. var. cobrensis Roll. & Shaw) were encountered and evaluated with reference to current or potential threats, and are recommended for placement on Idaho's State Watch List.         

Ecophysiology of the temperate desert halophytes: Allenrolfea occidentalis and Sarcobatus vermiculatus

Numerous basins of the intermountain area often have extensive playa surfaces that are nearly devoid of vegetation. Margins of these playas support sparse communities dominated by chenopod shrubs Allenrolfea occidentalis (iodine bush) and Sacrobatus vermiculatus (black greasewood). These plants establish and persist in an environment where halomorphic soils induce extreme osmotic stress and atmospheric precipitation is very low and erratic and occurs largely during the winter when temperatures are too low for growth. We measured net CO 2 assimilation rates, leaf conductances, transpiration rates, water-use efficiencies, and stem xylem potentials for these two C3 species. Data were collected in above-average (1991) and below-average (1992) precipitation years. Net CO 2 assimilation rates for Allenrolfea were statistically similar in 1991 and 1992 but in general declined for Sarcobatus in 1992. For both species, leaf conductances and leaf transpiration rates declined significantly from 1991 to 1992, with the decline greater for Sarcobatus . Water-use efficiencies doubled from 1991 to 1992 for both plant species. Predawn xylem water potentials were -2.2 and -3.3 MPa for Allenrolfea and -1.8 and -2.6 MPa for Sarcobatus by September 1991 and 1992, respectively. Afternoon xlem water potentials were -3.1 and -2.0 MPa for Allrolfea and -2.6 and -2.2 for Sarcobatus beginning in May 1991 and 1992, respectively. Xylem water potentials dropped to -5.0 MPa for Allenrolfea and -3.4 MPa for Sarcobatus by September for both 1991 and 1992. For Allenrolfea , in general, the total soil water potential within the zone of maximum root activity is more negative than the plant's predawn xylem potential, which suggests that the plant is partially phreatophytic and/or has a large capacitance due to its extensive woody root system.