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Our studies of the association between the lesser earless lizard (Holbrookia maculata) and Gunnison's prairie dogs (Cynomys gunnisoni) revealed: (1) the lesser earless lizard was more abundant on prairie dog colonies than off, (2) lesser earless lizard abundance was positively correlated with prairie dog burrow abundance; (3) lesser carless lizards responded positively to artificial burrows created on noncolonized areas; and (4) lesser earless lizards used prairie dog burrows as refuges from predators; however, the relative use of burrows was greatest at high and low temperature extremes. Although prairie dogs alter habitat in many ways, our study suggests that burrows are an important mechanism involved in the...
Contrary to the reports of several authors, Acomus generosus, a sucker of the subgenus Pantosteus of Catostomus, may have been collected in Big Cottonwood Creek or Little Cottonwood Creek, Salt Lake County, Utah, and possibly in Provo River, Utah County, Utah. Multiple Pantosteus species may exist in Provo River. Synonymies of the suckers that have been collected in Provo River and ?Cottonwood Creek? are provided. A comparison of their morphologies shows several distinctions. There is a need for further systematic (including up-to-date biochemical) analyses of these catostomids. Published in American Midland Naturalist, volume 143, issue 2, on pages 422 - 432, in 2000.
Artemisia tridentata has increased dramatically during the past 100 yr throughout the sagebrush steppe at the expense of late-seral perennial grasses. This study was designed to determine the effects of addition or depletion of different nitrogen forms on aboveground vegetative and reproductive growth of Artemisia tridentata ssp. wyomingensis and Stipa thurberiana, a late-seral grass. Treatments included application of sugar (45 g m-2), nitrate (4.5 g N m-2), ammonium (4.5 g N m-2) and a control. Both nitrogen forms significantly increased Stipa aboveground biomass and tiller density. Individual tiller weight was not different among treatments. Added nitrogen also increased aboveground biomass, total shoot density...
A study was conducted from July 1965 to September 1966 on the biology of Gunnison's prairie dog (Cynomys gunnisoni gunnisoni) in South Park, Park Co., Colorado. Prairie dogs within the colony were loosely organized into clans with adult females playing the major role in caring for the young and! warning of danger. Clan boundaries were not patrolled or defended by clan members, but individual burrows, burrow systems or food supplies were protected by individual animals. Little aggression was observed within the clans but members of different clans would engage in disputes when they encountered each other in the common feeding areas. Females had a high ratio of successful pregnancies or uterine implantation sites,...
Ephemeral plant biomass and density on a Sonoran Desert hill near Cave Creek, Arizona, vary relative to shrub canopy type and shrub density. Higher shrub density associated with increased elevation appears to decrease both ephemeral biomass productivity and density, while ephemeral growth is enhanced under a shrub canopy if it is not too dense or low-hanging. Phenology of ephemerals on the desert study site shows early cool-season germination, low tolerance to heat, and early flowering when compared to shrubs and succulents in the same area. Published in American Midland Naturalist, volume 93, issue 2, on pages 311 - 319, in 1975.
Litter production by Artemisia tridentata, Atriplex confertifolia and Ceratoides lanata plants was monitored from 1970 to 1974 in Curlew Valley, Utah. Chemical analysis of litter collected in 1971 was combined with data on total phytomass and net primary production collected in previous studies in the same area to estimate turnover rates of tissues and minerals. Litter production averaged 128.5, 175.6 and 191.9 g m-2 year-1 for the Ceratoides, Atriplex and Artemisia communities, respectively. This is much higher than would be predicted from a recently published model stressing evapotranspiration as the major driving variable. The percentages of aboveground phytomass that become litter, ranked in order, were Ceratoides...
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Numerous anthropogenic and natural factors affect living organisms in nature. Anthropogenic factors include a wide array of contaminants and processes that alter the habitat on both local and global scales. For example, chlorofluorocarbons (CFCs) and other industrial gases contribute to the depletion of the earth?s protective ozone layer, resulting in increased amounts of cell damaging ultraviolet-B (UV-B) radiation reaching the surface of the earth. Recent experiments provide evidence that increasing ambient levels of UV-B radiation harm many amphibian species. UV-B radiation can kill amphibians and can cause sublethal damage to them. However, most studies that have examined the effects of UV-B radiation on amphibians...
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Contrary to the reports of several authors, Acomus generosus, a sucker of the subgenus Pantosteus of Catostomus, may have been collected in Big Cottonwood Creek or Little Cottonwood Creek, Salt Lake County, Utah, and possibly in Provo River, Utah County, Utah. Multiple Pantosteus species may exist in Provo River. Synonymies of the suckers that have been collected in Provo River and “Cottonwood Creek� are provided. A comparison of their morphologies shows several distinctions. There is a need for further systematic (including up-to-date biochemical) analyses of these catostomids. Published in American Midland Naturalist, volume 143, issue 2, on pages 422 - 432, in 2000.
Relatively low but significant rates of N2 fixation (C2H2 reduction) associated with rhizosheaths of Indian ricegrass Stipa hymenoides varied inversely with percent O2 in test atmospheres, and directly with percent water-holding capacity of sand substrate. Nitrogen fixation was not observed for plants tested in late summer or for nonrhizosheath plants inhabiting nonsandy soil. Delayed linear rates of C2H2 reduction preceded by ca. 24-48 h lag periods were observed. Published in American Midland Naturalist, volume 126, issue 1, on pages 76 - 81, in 1991.
The pattern of vegetation types has changed markedly at Devils Tower in the past 100 years. Fire scars on ponderosa pine (Pinus ponderosa Laws.) at the Monument indicate that there has been a marked change in fire frequency over this period. Changes in fire regime are clearly important in driving the changes in vegetation pattern. Studies of soil-borne opal phytoliths also indicate the presence of a stable ecotone in the past followed by a dynamic boundary in recent times. Changes in fire frequency from 1770-1900, a time when the Sioux were rapidly expanding into the Black Hills, indicates that native Americans may have dramatically affected the prairie-forest mosaic observed by early Europeans Published in American...
A population of Coleonyx variegatus was studied during 1965-66 at a low-altitude Sonoran Desert mountain range. Seasonal activity extended from April through October, with intermittent activity during winter months. Mean distances between capture points ranged from 10.9 m for immature males to 43.7 m for immature females. Frequency of broken or regenerated tails was positively correlated with body length; in the largest size group 74.1 % were broken. Growth rates varied from 9.7 mm/month in immature lizards to no discernible growth for large adults. Gravid females were found from April through September, occurring most frequently in May and June. Two or more clutches of two eggs each are produced annually. Males...
Desert iguanas in the Coachella Valley of California fed primarily on annual plants in the spring and shifted almost entirely to the leaves of desert perennials during the summer. Insects and fecal material always comprised a small portion of the diet. In summer at Palm Desert these lizards obtained about 1.0 liters of water per kg of dry food which contained 364 meq K+, 34 meq Na+ and 105 meq Cl-. In spring the foods were more succulent but contained virtually the same concentrations of electrolytes. At Thousand Palms the summer diet was drier and contained higher concentrations of cations. In summer desert iguanas turned over about 30 ml of water/(kg x day) when maintaining weight on natural vegetation in Palm...
Artemisia tridentata on the A. tridentata-Agropyron spicatum habitat type (h.t.) annually sheds approximately 117 kg/ha of leaf and inflorescence litter as determined by collecting litter of shrubs enclosed in nylon net cages. Total available amounts of cations (kg/ha) to a depth of 1 m on this h.t. are: Ca, 21,936; Mg, 4450; P, 127.2; and K, 3588. On the adjacent A. tridentata-Poa secunda h.t., approximately 1/2 of the leaf litter is lost in the 1st year on the soil surface with an element mobility series of K> Mg> P = Ca. Inflorescence litter apparently decays completely within 6 months after abscission. Published in American Midland Naturalist, volume 97, issue 1, on pages 189 - 197, in 1977.
Defining the trophic position of stream organisms is a first step in understanding the ecology of lotic systems. Whereas trophic positions of stream fishes have been traditionally assigned based on dietary analysis, stable isotope ratios may provide additional information on the validity of this approach and may be used to verify energy acquisition assumed from dietary studies. In this study, we assessed the concordance of literature-based trophic classifications and isotopic ?15N signatures for small-bodied fishes from four streams in Kansas, Oklahoma and New Mexico. ANOVA results revealed no significant difference (F2,27 = 1.71, P = 0.201) in trophic position based on ?15N values among three broad trophic classifications...
Between 1964 and 1968, 20 species of Hirudinea were collected in Colorado, 12 of which are new records for the state. A wide variety of sites were visited in all 63 Colorado counties, including 87 lotic and 443 lentic stations. A total of 6726 leeches were collected from 32 lotic sites and 261 lentic sites. Some species are geographically or altitudinally restricted; others are widely distributed. Helobdella stagnalis is the most abundant and widely distributed leech in Colorado. Erpobdella punctata, Haemopis marmorata, Glossiphonia complanata, Placobdella ornata, and Theromyzon rude are also widespread. Batracobdella phalera is found only in the foothills zone and montane zone, whereas B. picta occurs from the...
Raptors were counted at approximately 2-week intervals between March and November 1985-1987 in the Moreno Valley, Colfax Co., New Mexico. During that period, an epizootic of plague (Yersinia pestis) swept through the valley and sequentially killed Gunnison's prairie dogs (Cynomys gunnisoni) in three areas of approximately 25 km2 each. Red-tailed hawk (Buteo jamaicensis) numbers did not change significantly over the study period. Although golden eagles (Aquila chrysaetos) declined in abundance, their numbers did not recover with the recovery of prairie dogs in 1987. Ferruginous hawks (B. regalis) were abundant during autumn migration where prairie dogs were abundant, but their numbers declined significantly with...
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The largest population of endangered humpback chub Gila cypha inhabits the Colorado River below Glen Canyon Dam and the lower 14 km of the Little Colorado River (LCR), Arizona. Currently, adults from both rivers spawn and their progenies grow and recruit to adulthood primarily within the LCR, where we studied G. cypha's life history using hoop net capture data. Humpback chub undergo an ontogenesis from diurnally active, vulnerable, nearshore-reliant young-of-the-year (YOY; 30–90 mm total length) into nocturnally active, large-bodied adults (≥180 mm TL). During the day, adults primarily resided in deep midchannel pools; however, at night they dispersed inshore amongst the higher densities of YOY conspecifics. Many...
The noteworthy aspect of the discovery lies less in the extension of the range of the species than in the environmental setting in which the animals occur. Xantusia vigilis has been considered one of relatively few vertebrates that exhibits close association with a plant type. Its range corresponds closely with the distribution of plants of the genus Yucca. Although previous records of occurrence have by no means indicated that the lizards are invariably re- stricted to association with these plants, by far the majority of individuals have been found in areas where they are abundant. They occur beneath dead fallen trees and limbs and among the spiny leaves of Joshua trees (Yucca brevifolia) and beneath the rosettes...
The sounds of black-tailed, white-tailed, and Gunnison's prairie dogs were studied in Colorado and Wyoming from February 1964 to June 1966. Observations, photographs, and tape recordings were made in the field and were supplemented by data collected from captive prairie dogs. The sounds of black-tailed prairie dogs were named and had the usual function as follows: ( 1 ) "repetitious barks" alert; (2) "chuckle" alert; (3) "chatter barks" - threat; (4) "wee-oo" - contact; (5) "snarl" - threat; (6) "growl" threat; (7) "scream" - distress; (8) "raspy purr" - pleasure; and (9) "tooth chatter" - threat. The sounds of white-tailed prairie dogs were: (1) "repetitious barks" alert; (2) "chuckle" alert; (3) "laughing barks"...
The influence of intensive grazing on canopy microclimate, grass leaf water relations and community evapotranspiration was investigated by comparing a grassland heavily grazed by a colony of black-tailed prairie dogs (Cynomys ludovicianus) with an adjacent lightly-grazed, uncolonized area in a northern-mixed prairie in South Dakota. Total above-ground plant biomass was lower on the colony through the growing season. Daytime leaf and air temperatures were higher on the colony. Although daytime air vapor pressure in the canopy was higher on the colony, higher leaf temperatures resulted in higher leaf-to-air vapor-pressure differences on the colony. Along with higher vapor-pressure differences, higher wind speeds within...


map background search result map search result map Ontogenesis of Endangered Humpback Chub (Gila cypha) in the Little Colorado River, Arizona Ambient levels of ultraviolet-B radiation cause mortality in juvenile western toads, Bufo boreas Suckers of the Subgenus Pantosteus from Provo River and “Cottonwood Creek�, Utah Suckers of the Subgenus Pantosteus from Provo River and “Cottonwood Creek�, Utah Ontogenesis of Endangered Humpback Chub (Gila cypha) in the Little Colorado River, Arizona Ambient levels of ultraviolet-B radiation cause mortality in juvenile western toads, Bufo boreas