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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,...
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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...
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...
Eighty-six scats were analyzed to determine food habits of wild black- footed ferrets (Mustela nigripes). Most scats were collected during winter (N = 27) and spring (N = 27); scats from summer (N = 2), autumn (N = 2) and from undetermined seasons (N = 28) accounted for the remainder. White-tailed prairie dog remains oc- curred in 87% of all scats. Mouse remains were found in 6% and lagomorph remains in 3 % of scats. Published in American Midland Naturalist, volume 117, issue 1, on pages 208 - 210, in 1987.
Volatile substances, probably terpenes, exuded from Artemisia tridentata var. vaseyana may inhibit its associates under field conditions. (1) At high concentrations volatile exudates inhibit the growth of seedlings, lower the respiration rates of juvenile plant material and raise the respiration rates of mature plant material. Monoterpenes found in Artemisia, the presumptive toxins, also raise the respiration rates of mature wheat leaves. (2) Wheat plants exposed to Artemisia exudates in the field (chronic low concentrations) have higher respiration rates than controls. This suggests that volatile phytotoxins may inhibit established competitors as well as establishing competitors. Published in American Midland Naturalist,...
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Erigeron kachinensis is a rare endemic of the Colorado Plateau regions of southeastern Utah and southwestern Colorado. It occurs in small, isolated alcoves (recessed areas in canyon walls) at seeps arising along canyon walls in sandstone substrates. One hundred randomly selected individuals of E. kachinensis within each of six alcoves in Natural Bridges National Monument, San Juan County, Utah, were monitored for 5 yr (1990-1994). Survival of the 600 individuals was followed over the monitoring interval. Vegetative and reproductive parameters were assessed for the survivors each year. Mortality varied among the study alcoves and individual size-classes. Mortality was heavily concentrated in the smaller size-classes....
We live-trapped rodents in 2000-2001 at eight sites on a 3160 ha grassland and mesquite-oak savanna in southeastern Arizona that had been ungrazed since 1968, and on eight paired sites on adjacent cattle ranches. There were 917 captures of 14 species during 5760 trap-nights. Four species of Muridae (Sigmodon fulviventer, Baiomys taylori, Reithrodontomys megalotis and R. fulvescens) were significantly more common on ungrazed plots, while no species was more abundant on grazed plots. However, Heteromyidae as a group (especially Chaetodipus hispidus and Perognathus flavus) comprised a significantly higher proportion of total captures on grazed plots, and heteromyids as a percentage of total captures was positively...
ABSTRACT: The rate of invasion of Tamarix pentandra Pall. into the vegetation bordering Utah Lake, Great Salt Lake, Colorado River, and Green River in Utah was determined from historical information and scientific studies. There are no records of tamarix at the above listed lakes and streams prior to 1925. The period from 1925 to 1960 was one of rapid spread and increase in importance of tamarix. The greatest degree of invasion occurred from 1935 to 1955. At the present time, naturalization is occurring along the mountain streams and reser- voirs of the Wasatch Mountains. Published in American Midland Naturalist, volume 68, issue 1, on pages 51 - 57, in 1962.
    map background search result map search result map Demography and Life History Characteristics of the Rare Kachina Daisy (Erigeron kachinensis, Asteraceae) 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 Demography and Life History Characteristics of the Rare Kachina Daisy (Erigeron kachinensis, Asteraceae) 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