A comparison of bird populations on Mount Crested Butte and Snodgrass Mountain - J. Chodosh (1994)

Acidification and salamander recruitment - J. Harte; E. Hoffman (BioScience, 1994)
Journal Article Acidification and Salamander Recruitment Get access John Harte, John Harte Energy and Resources Group, University of California, Berkeley, CA 94720 Search for other works by this author on: Oxford Academic Google Scholar Erika Hoffman Erika Hoffman Energy and Resources Group, University of California, Berkeley, CA 94720 Search for other works by this author on: Oxford Academic Google Scholar BioScience, Volume 44, Issue 3, March 1994, Pages 125–126, https://doi.org/10.2307/1312246 Published: 01 March 1994

Vegetation and tree abundance at active and non-active beaver ponds - E. MacDonald (1994)

Bumblebee foraging behavior: the roles of floral scent and color - E. Odell (1994)

A study of Clethrionomys gapperi habitat preference on Snodgrass - S. Advani (1994)

Pollen discounting in Erythronium grandiflorum: mass-action estimates from pollen transfer dynamics - K. E. Holsinger; J. D. Thomson (American Naturalist, 1994)
Pollen discounting, a reduction in success as an outcross pollen parent as a result of selfing, can reduce or eliminate the reproductive advantage commonly attributed to selfing. Previous estimates of pollen discounting have been based on segregation analysis of progeny from open-pollinated plants. Using data from Erythronium grandiflorum, we illustrate how direct measures of pollen transfer can be used to estimate discounting rates, and we discuss the relationship between absolute discounting rates measured in this way and relative discounting rates measured through segregation analysis. Only about 0.4% of the pollen removed from anthers in E. grandiflorum is used in selfing, and only a little more (0.5%) is delivered to the stigmas of other plants. Using these estimates in the framework of a mass-action model suggests that the success rate of self-pollen is almost 80 times that of outcross pollen. Thus, variants increasing the discounting rate would appear to have a substantial reproductive advantage in E. grandiflorum. Pollen discounting cannot explain the maintenance of an outcrossed mating system in E. grandiflorum, and it may also fail in other plants in which a large proportion of the pollen produced never reaches a receptive stigma.

Effects of pumping on the East River - J. Renfrow (1994)

Effects of floral traits, pollinator visitation, and plant size on Ipomopsis aggregata fruit production - R. J. Mitchell (American Naturalist, 1994)
Current understanding of reproduction for animal-pollinated plant species is based on the premise that traits of flowers and inflorescences influence reproductive success by affecting pollinator behavior. This implies that within-population variation in such traits should affect reproductive success. I used path analysis and structural equation modeling to test this hypothesis for two populations of the monocarpic herb Ipomopsis aggregata (Polemoniaceae). The basic hypothesis proposes that pollinator behavior may be affected by plant traits (including floral nectar production rate, corolla size, number of open flowers, and inflorescence height) and that behavior, along with plant size, may influence reproductive success through female function (proportion fruit set and total fruit production). This hypothesis was consistent with the data in both populations, although the specific details of the appropriate formulation varied. For both populations, the basic hypothesis is significantly better as a description of the interactions than alternative hypotheses that ignore the effects of plant traits on pollinator behavior or plant size on reproduction. In one population, disallowing the effects of pollinator behavior on reproduction significantly decreased the fit of model to data, and in the other, the decrease was almost significant (P = .06). Overall, the fundamental causal relationships proposed in the basic hypothesis were confirmed.

Survival of dispersing and philopatric yellow-bellied marmots: what is the cost of dispersal? - D. H. Van Vuren; Kenneth B. Armitage (Oikos, 1994)
Understanding the evolution of dispersal has been hindered by a lack of reliable measures of the cost of dispersal. We report that survival of dispersing yellow-bellied marmots (Marmota flaviventris) (0.73) was only 16% less than survival of philopatric marmots (0.87). A cost-benefit analysis reveals that the survival cost of dispersal may be less than some other costs of philopatry; thus, dispersal is explicable as a tactic to improve individual fitness

Cougars and conservation biology - A. Wojtalik (1994)

The relationship between stream velocity and body size of Blephariceridae larvae - the net-winged midge - J. V. Peck (1994)

Comparison of stonefly habitat on various sized rocks - A. Prussian (1994)

The effect of pH and other pollutants on benthic invertebrates in a pristine alpine watershed in central Colorado - G. L. Rouse (1994)

The activity patterns of the long-legged bat, Myotis volans in conjunction with habitat - A. Hines (1994)

The effects of light intensity on the activity of predacious stonefly nymphs on mayfly nymphs - C. Lake (1994)

Ecological restoration: a solution or a problem? - P. D. Mariner (1994)

The Birds of North America - L. L. Calder; L. L. Calder; L. L. Calder; L. L. Calder (1994)

Techniques for Pollination Biologists - C. A. Kearns; David W. Inouye (1993)

Geitonogamy: the neglected side of selfing - T. J. De Jong; Nickolas M. Waser; Peter G.L. Klinkhamer (Trends in Ecology and Evolution, 1993)
Selfing by geitonogamy incurs a fitness cost of reduced pollen export, and recent reports show that seed set can suffer as well, even in self-incompatible species.

Proceedings of the International Symposium on Pollination in Tropics - David W. Inouye; C. A. Kearns; Mary V. Price; Nickolas M. Waser (1993)

Sublethal consequences of stream-dwelling predatory stoneflies on mayfly growth and fecundity - B. L. Peckarsky; C. A. Cowan; M. A. Penton; C. Anderson (Ecology, 1993)
Predators can have consequences on prey populations and communities that extend well beyond direct predator—induced mortality. Predator—prey interactions often affect prey feeding rates, growth rates, or fecundities, thereby significantly affecting reproductive success of prey adults. Thus, investigation of the sublethal fitness consequences of behavioral responses of prey to predators is essential to our understanding of the total impact of predators on prey populations and communities. Feeding (algal grazing) rates, growth rates, and fecundities of Baetis bicaudatus (Baetidae) larvae were measured in replicated circular flow—through stream channels to determine the sublethal consequences on fitness correlates of the presence of predatory stoneflies (Perlodidae). Gut fullness of 24—h starved Baetis larvae was measured using fluorometry after 24 h (short—term experiments) in four treatments: (1) ambient resource rocks and no predators, (2) low resource rocks and no predators, (3) ambient resource rocks and one female perlodid stonefly (Megarcys signata), or (4) Kogotus modestus whose mouthparts were glued to prevent lethal effects of predation. Mid—instar male and female Baetis larvae were reared for 3 wk until wing pad maturation (long—term experiments) and subjected to all but the Kogotus treatment. Predator avoidance significantly reduced levels of Baetis gut fullness, over the short term, to levels intermediate between the high and low resource treatments. Longer term residence with predatory stoneflies caused larvae of both male and female Baetis to mature at significantly smaller sizes than in the treatment with ambient food but no predators. Mayflies with predators matured at sizes similar to those held with low food levels over the long term. Interestingly, both starved larvae and those avoiding predators did not grow during the experimental period in contrast to about a 50% growth rate of larvae experiencing ambient food levels, but no predators. Similarly, egg biomass per mature female larva was significantly reduced in both starved and predator treatments. The proportion of total body mass allocated to eggs was only reduced in starved mayflies indicating that the females avoiding predators accrued less total mass, but allocated a similar proportion to eggs as did well—fed Baetis. These data convincingly demonstrate that predator avoidance can have dramatic consequences on mayfly fitness. The mechanism explaining those fitness consequences is probably a disruptive drift/swim response by Baetis to encounters with stoneflies, which reduces Baetis' feeding rates. If we accept the assumption that natural selection has shaped the foraging behavior of organisms to maximize fitness, foragers need to make decisions that maximize both survivorship (minimizing risk of predation) and fecundity. In mayflies fecundity is entirely a function of resource acquisition by the larvae, which makes them particularly vulnerable to such sublethal effects of predation. Nonetheless, we suspect that the types of sublethal costs of predator avoidance documented by this and other recent studies are nearly universal consequences or organisms foraging under predation risk.

Resource and pollen limitations to lifetime seed production in a natural plant population - Diane R. Campbell; K. J. Halama (Ecology, 1993)
Using experimental manipulations, we examined pollen and resource limitations to seed production and their interaction in a natural population of a monocarpic plant, Ipomopsis aggregata. Our design cross two factors, pollen level (hand—pollinated or control) and resource level (water added, water and fertilizer added, or control). Both hand—pollination and fertilizing during the blooming season increased total seed production, while watering alone has no effect on any component of reproductive success. Hand—pollination boosted number of seeds per flower, with no effect on flower number. In contrasts, fertilizing had its primary effect on the number of flowers produced, while also increasing the number of seeds per mature fruit in hand—pollinated plants. Fertilizing increased nectar volume, but path analysis detected no indirect effect of this increased reward rate on seed production, suggesting instead that fertilizing has a slight, but direct, effect on seeds per flower. These results argue against a strict dichotomy between pollen limitation and resource limitation of female reproductive success in plants.

Vascular Plants of the Gothic Area - P. Buck; B. A. Frase (1993)

Migration of rufous hummingbirds - W. A. Calder (Wildbird, 1993)

Microclimate amelioration may be critical to recovery of subalpine ecosystems (Colorado) - C. G. Curtin (Restoration and Management Notes, 1993)

The effect of molt on oxygen consumption of yellow-bellied marmots (Marmot flaviventris) - Kenneth B. Armitage; C. M. Salsbury (Comparative Biochemistry and Physiology, 1993)

Hypothesis concerning the causes of the disappearance of boreal toads from the mountains of Colorado - C. Carey (Conservation Biology, 1993)
Recent reports of world‐wide declines and extinctions of amphibian populations have raised questions about the relation of environmental change to the demise of certain amphibian species. Between 1974 and 1982, 11 populations of boreal toads ( Bufo boreas boreas ) in the West Elk Mountains of Colorado totally disappeared. The apparent cause of extinction of these toads was infection with the bacteria Aeromonas hydrophila . In this paper, the presence of disease in declining populations of these toads is used in conjunction with a variety of data from the literature to formulate a working hypothesis for explaining the cause of the decline of this species, and perhaps others: Some environmental factor or synergistic effects of more than one factor changes sufficiently to cause sublethal “stress”; This stress directly causes suppression of the immune system, or indirectly causes immunosuppression by effecting elevated secretion of adrenal cortical hormones; Immunosuppression, coupled with the apparent effect of cold body temperatures on the ability of immune systems of ectothermic animals to fight disease, leads to infection by Aeromonas or other infectious agents and to subsequent death of individuals and extinction of populations.

Heartwood decay and vertical distribution of red-naped sapsucker nest cavities - G. C. Daily (Wilson Bulletin, 1993)

Birding for fun: Sapsuckers, swallows, willow, aspen and rot - P. R. Ehrlich; G. C. Daily (American Birds, 1993)

Parentage analysis in ant colonies using simple sequence repeat loci - J. D. Evans (Molecular Ecology, 1993)

Comparison between plant species in bushy-tailed woodrat middens and in the habitat - B. A. Frase; W. E. Sera (Great Basin Naturalist, 1993)

Temporal Organization: Reflections of a Darwinian Clock-Watcher - C. S. Pittendrigh (Annual Review of Physiology, 1993)
Macrophage polarization refers to how macrophages have been activated at a given point in space and time. Polarization is not fixed, as macrophages are sufficiently plastic to integrate multiple signals, such as those from microbes, damaged tissues, and ...Read More

Differential success of pollen donors in a self-compatible lily - L. P. Rigney; J. D. Thomson; M. B. Cruzan; J. Brunet (Evolution, 1993)

Floral mimicry by a plant pathogen - B. A. Roy (Nature, 1993)
An extraordinary case of pathogen-mediated floral mimicry that contributes to fungal reproduction of the rust fungus Puccinia monoica is reported.

Patterns of rust infection as a function of host genetic diversity and host density in natural populations of the apomictic crucifer, Arabis holboellii - B. A. Roy (Evolution, 1993)
It is often assumed that genetic diversity contributes to reduced disease incidence in natural plant populations. However, little is known about the genetic structure of natural populations affected by disease. Here I present data from three apomictic (asexual) populations of Arabis holboellii infected by the rusts Puccinia monoica and P. thlaspeos. An average of 300 host individuals per population were genotyped (using seven variable allozyme loci) and scored for disease presence. Arabis holboellii populations are genetically diverse; the number of clones detected per population ranged from 6 to 27. There was substantial variation in frequency of host clones within and among sites, and significant variation among clones in susceptibility to the different rusts. Contrary to predictions based on frequency-dependent selection theory there was not a consistent positive relationship between clone frequency and disease incidence within any of the populations (Spearman's r = -0.096, P > 0.5). In addition, clonally diverse populations did not necessarily have decreased disease incidence. The population with the lowest overall (both pathogens combined) disease incidence (7.5 ± 1.9%) had the smallest number of clones (6), the lowest spatial variability, and the highest Arabis density. By comparison, another population had 22 clones, high spatial variability, low Arabis density and significantly more disease overall (16.8 ± 2.7%). Although this study does not eliminate the possibility of frequency-dependent pathogen attack in these populations, the results suggest that it is likely to be weak or intermittent.

Disruptive selection in flowering time of Wyethia amplexicaulis (Asteraceae) - K. Suzuki (Plant Species Biology, 1993)

Colonization, interaction, and organization of cladoceran epibiont communities - S. T. Threlkeld; R. L. Willey (Limnology and Oceanography, 1993)

Organization of crustacean epizoan communities in a change of subalpine ponds - R. L. Willey; S. T. Threlkeld (Limnology and Oceanography, 1993)

Intraguild predation and competition between larval dragonflies: direct and indirect effects on shared prey - S. A. Wissinger; J. McGrady (Ecology, 1993)
We conducted manipulative field experiments in artificial ponds to quantify the predatory impact of larvae of a migratory dragonfly (Tramea lacerata) on a common resident dragonfly species (Erythemis simplicicollis), and on damselflies as shared prey of the two dragonflies. We found that the combined predatory effects of these two dragonflies on damselflies were not additive. To determine the underlying cause of non—additive predation rates in the field, we conducted a second experiment in laboratory aquaria to isolate the impact of each predator on the consumption rates of the other. Dragonfly consumption rates of damselflies in single—predator treatments were compared to those in the presence of heterospecifics or conspecifics with their menta (mouthparts) surgically modified so that they could not capture prey. In the laboratory experiment, de—mented Tramea reduced the consumption rates of Erythemis to less than half of that observed when Erythemis foraged alone. Erythemis numbers were also reduced by Tramea predation. Erythemis had neither effect on Tramea. Both of the negative effects of Tramea on Erythemis will have indirect positive effects on damselflies. The "behavioral" component (reduced Erythemis foraging rate) should be more important than the "trophic link" (reduced Erythemis numbers) indirect effect. Together these indirect positive effects will allay, but not completely compensate for, the direct negative effects of Tramea predation on damselflies. These results illustrate how an asymmetric potential for intraguild predation can lead to asymmetries in interference competition and to non—additive effects on prey mortality. The addition of removal of predators that interact in this manner to or from communities should have only a small net effect on prey because of compensating direct and indirect effects. This may explain why predator manipulations have often had unpredictable or undetectable effects on freshwater benthic communities.

Life in the Cold: Ecological, Physiological and Molecular Mechanisms - C. Carey; G. L. Florant; B. A. Wunder; B. Horwitz (1993)

The Green Fuse: An Ecological Odyssey - J. Harte (1993)

Design and Analysis of Ecological Experiments - R. J. Mitchell (1993)

Prceedings of the International Symposium on Pollination in Tropics - R. B. Primack; David W. Inouye (1993)

Biological Field Stations: Opportunities for undergraduate and faculty research - R. J. Smith (1993)

The BLM’s restoration of a braided reach of the Slate River: “If you’re gonna do it, do it right.” - A. Benson; E. Odell; H. Rustigian (1993)

An assessment of the effects of powdertracking on small mammals - A. Benson (1993)

Microtine population in a spruce-fir avalanche area - S. A. Bookhout (1993)

Quantification of secondary pollen carryover in Erythronium grandiflorum (Liliaceae) - K. A. Eisenhart (1993)

A comparative population study of an avalanche site and the neighboring standing forest - E. Fetterley (1993)

The diet of the red fox - D. Glicklich (1993)

Bumblebee foraging: can observed preferences of two bee species be explained by their foraging efficiencies on flowers of two different plant species? - L. Graham (1993)

Use of macroinvertebrates to assess water quality at three sites along the East River - A. Hall (1993)

The occurrence of Myotis volans and other Myotis spp. in areas surrounding Gothic - J. Hertzig (1993)

Alternatives for the restoration of Gothic - J. Hertzig; K. Walker (1993)

Feeding behavior as affected by the risk of predation in T. minimus and S. lateralis - D. Hutcheson (1993)

Evaluation of mitigated wetlands, Gunnison, CO - J. Klumpp; N. Neitzel (1993)

The Natural History of Inbreeding and Outbreeding, Theoretical and Empirical Perspectives - Nickolas M. Waser (1993)

Carrion beetle distribution and effects on larval development and brood size - S. Kaufman (1993)

The effects of nectar robbing on the reproductive success of Ipomopsis aggregata - K. Kuta (1993)

The behavioral effects of intraspecific predation on larval tiger salamanders: an investigation of life history variation in montane populations of Ambystoma tigrinum - J. M. Marcus (1993)

Recruitment and aggression in Formica neorufabarbis (Hymenoptera: Formicidae) - Raymond C. Moore (1993)

The longevity of a yellow fluorescent powder on a small nocturnal rodent, Peromyscus maniculatus - E. Odell (1993)

The effects of avalanche disturbance on the diversity and abundance of small mammals in an aspen stand near Gothic, Colorado - C. Rideout (1993)

Behavioral observations of Ochotona princeps: foraging and haypiles - E. Rosi (1993)

A characterization of the minimum home range of the western jumping mouse (Zapus princeps) - M. Steiner (1993)

Pollinator mediated selection in an Ipomopsis hybrid zone in Poverty Gulch, Gunnison County, Colorado - M. Steiner (1993)

The use of Bayesian foraging to evaluate novelty by T. minimus and S. lateralis - T. A. Strickland (1993)

The influence of environmental variables on the timing of emergence of bats (Myotis spp.) from diurnal roosts - J. Stortz (1993)

Field performance of woodburning stoves in crested butte, Colorado - Dennis R. Jaasma; Mahesh Gundappa; Mark R. Champion; Robert C. Mccrillis (Environmental Monitoring and Assessment, 1993)
The carbon monoxide (CO) and particulate matter (PM) emissions of woodburning stoves have been measured under field conditions and the rate reductions occur because the certified stoves burn cleaner and the average burn rate of certify stoves in field use is less than the averageBurn rate of conventional stoves.

The effects of habitat variability on the ectoparasites of P. maniculatus - B. Sullivan (1993)

Mowing as a management tool for increasing forage for wildlife and livestock at Cabin Creek, CO - G. R. Yaksich (1993)

Connoisseur's Choice: Rhodochrosite Alma, Park County, Colorado - Robert B. Cook (Rocks & Minerals, 1993)

Double keystone bird in a keystone species complex - G. C. Daily; P. R. Ehrlich; N. M. Haddad (Proceedings of the National Academy of Sciences, USA, 1993)
Species in a Colorado subalpine ecosystem show subtle interdependences. Red-naped sapsuckers play two distinct keystone roles. They excavate nest cavities in fungus-infected aspens that are required as nest sites by two species of swallows, and they drill sap wells into willows that provide abundant nourishment for themselves, hummingbirds, orange-crowned warblers, chipmunks, and an array of other sap robbers. The swallows thus depend on, and the sap robbers benefit from, a keystone species complex comprised of sapsuckers, willows, aspens, and a heartwood fungus. Disappearance of any element of the complex could cause an unanticipated unraveling of the community.

Watering the Land: The Colorado River Project - Kevin Starr (Southern California Quarterly, 1993)
Research Article| October 01 1993 Watering the Land: The Colorado River Project Kevin Starr Kevin Starr Search for other works by this author on: This Site PubMed Google Scholar Southern California Quarterly (1993) 75 (3-4): 303–332. https://doi.org/10.2307/41171683 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter LinkedIn Tools Icon Tools Cite Icon Cite Search Site Citation Kevin Starr; Watering the Land: The Colorado River Project. Southern California Quarterly 1 October 1993; 75 (3-4): 303–332. doi: https://doi.org/10.2307/41171683 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentSouthern California Quarterly Search This content is only available via PDF. Copyright 1993 Historical Society of Southern California Article PDF first page preview Close Modal You do not currently have access to this content.

The Birds of North America, No. 53 - W. A. Calder (1993)

Reproductive energetics of adult male yellow-bellied marmots - C. M. Salsbury (1993)

The relative role in parental care of a pair of nesting mountain bluebirds, Sialia currucoides - K. M. Wacker (1993)

Crossing distance effects on prezygotic performance in plants: an argument for female choice - Nickolas M. Waser; Mary V. Price (Oikos, 1993)
Seed set in the perennial larkspur Delphinium nelsonii is greater in crosses between plants growing an intermediate distance apart than in shorter and longer crosses. Since crossing distance is an attribute of a specific combination of parents, its effect on seed set represents an interaction of these parents, and since genetic similarity declines with physical distance in D. nelsonii populations, the interaction reflects parental genetic similarity. Understanding processes responsible for the effect is simplified if seed set differences result from prezygotic events, because in this case no inbreeding or outbreeding depression are involved. In 1990 we observed pollen tubes after performing crosses between plants separated by 1 m, 10 m, or 100 m, and found that the intermediate, 10 m crosses delivered the most tubes to the ovary

Insect oviposition patterns in flowers of Helianthella quinquenervis - E. D. Andrews (1993)

The organization of zooplankton epibiont communities - S. T. Threlkeld; D. A. Chiavelli; R. L. Willey (Trends in Ecology and Evolution, 1993)
This study examines the organization of communities whose populations are distributed among ephemeral habitat patches and the frequent molting of the crustacean exoskeleton keeps these epibiont populations in a state of constant renewal.

Planktivore effects on zooplankton epibiont communities: epibiont pigmentation effects - R. L. Willey; S. T. Threlkeld (Limnology and Oceanography, 1993)
We observed the development of epibiont communities on freshwater crustacean zooplankton from 12 July–31 August 1991 in three ponds: one with planktivorous fish, a second with planktivorous larval salamanders, and a third with planktivorous fish added midway through the sampling period. Prevalence, on zooplankton, of pigmented euglenoid epibionts (Colacium vesiculosum), alone and with unpigmented peritrich ciliates (Vorticella campanula and Epistylis sp.), was significantly reduced by the addition of planktivorous fish in the third pond, while the prevalence of peritrich ciliates alone was not. Neither of the ponds with unaltered planktivore regimes showed a similar pattern of change in prevalence of pigmented and unpigmented epibionts on zooplankton. The relative loss of pigmented euglenoid epibionts, after planktivore addition, suggests that epibiont color or contrast may increase the susceptibility of their substrate organisms to planktivores.

Proceedings of the International Symposium on Pollination in Tropics - Nickolas M. Waser; Mary V. Price (1993)

A proposal for monitoring the East River - K. J. Bihr; A. Hall; C. Rideout (1993)

APPLICATIONS OF A GIS FOR MODELING THE SENSITIVITY OF WATER RESOURCES TO ALTERATIONS IN CLIMATE IN THE GUNNISON RIVER BASIN, COLORADO1 - William A. Battaglin; LAUREN E. Hay; Randolph S. Parker; George H. Leauesley (JAWRA Journal of the American Water Resources Association, 1993)
ABSTRACT: The Gunnison River drains a mountainous basin in western Colorado, and is a large contributor of water to the Colorado River. As part of a study to assess water resource sensitivity to alterations in climate in the Gunnison River basin, climatic and hydrologic processes are being modeled. A geographic information system (GIS) is being used in this study as a link between data and modelers ‐ serving as a common data base for project personnel with differing specialties, providing a means to investigate the effects of scale on model results, and providing a framework for the transfer of parameter values among models. Specific applications presented include: (1) developing elevation grids for a precipitation model from digital elevation model (DEM) point‐elevation values, and visualizing the effects of grid resolution on model results; (2) using a GIS to facilitate the definition and parameterization of a distributed‐parameters, watershed model in multiple basins; and (3) nesting atmospheric and hydrologic models to produce possible scenarios of climate change.

The Effects of Environment and Culture on the Distribution of Prehistoric Dwellings at Chimney Rock Mesa, Colorado - Dale R. Lightfoot; Frank W. Eddy (The Geographical Journal, 1993)
Dale R. Lightfoot, Frank W. Eddy, The Effects of Environment and Culture on the Distribution of Prehistoric Dwellings at Chimney Rock Mesa, Colorado, The Geographical Journal, Vol. 159, No. 3 (Nov., 1993), pp. 291-305

Differing plant communities in environments of high and low densities of Formica obscuripes - J. Reithel (1993)

Effects of weather conditions on cliff swallow foraging - D. Morris (1993)

Factors affecting pollinator visitation rates: a biogeographic comparison - R. B. Primack; David W. Inouye (Current Science, 1993)

The effect of adult food limitation on life history traits in Speyeria mormonia (Lepidoptera: Nymphalidae) - C. L. Boggs; C. L. Ross (Ecology, 1993)
Variation in food availability is likely to occur in the wild, and may affect resource allocation to various life history traits. Quantitative adult diet restriction had no effect on life—span or mean individual egg mass, but reduced fecundity in the butterfly Speyeria mormonia. The sum of fecundity plus unlaid oocytes remaining in the ovaries at death declined in direct proportion to the reduction in the adult diet. This indicates that oocytes were resorbed and resources re—allocated away from reproduction under resource stress, since the sum of laid and unlaid eggs for butterflies fed ad libitum did not differ from the number of oocytes present in the ovaries at eclosion. In this nectivorous species, then, life—span is conserved at the expense of reproduction under adult resource stress. Further, for butterflies fed ad libitum, the volume of honey—water imbibed declined with age for both sexes. Daily volume imbided by females fed ad libitum was directly correlated with daily egg production and life—span, suggesting that factors as yet unexplored may be affecting both resources intake and life history traits when resources are available ad libitum.

Hummingbird of the mountains - W. A. Calder (Wildbird, 1993)

Flora of the Fraser Experimental Forest, Colorado - Steve J. Popovich; Rocky Mountain Forest and Range Experiment Station (Fort Collins, Colo.) (1993)
the total precipitation falls as snow from October through May. As spring advances, snow disappears progressively from lower to higher elevations, and from south slopes first. The varied topography of the Forest is typical of the southern Rocky Mountains. The western portion of the Forest is characterized by rugged mountains and narrow, steep-sided valleys filled with alluvium and glacial outwash. Southern and eastern portions are remnants of an old peneplain, dissected by glaciers and characterized by long, gentle, relatively uniform slopes. The northern portion is a nearly level, broad valley dissected by St. Louis Creek and surrounded by rolling hills.

Climbing capabilities of Zapus princeps - J. A. Walton (1993)

The potential for rust infection to cause natural selection in A. holboellii - B. A. Roy; P. Bierzychudek (Oecologia, 1993)

Natural and human assisted recovery of anthropogenic damage at the Rocky Mountain Biological Laboratory (RMBL) - S. Feldhousen (1992)

The success of transplanted plants in a damaged ecosystem - J. T. Hutchinson (1992)

Patch choice in Peromyscus maniculatus: does cover affect perception of predation risk? - T. Grenager (1992)

Oviposition choices by a pre-dispersal seed predator (Hylemya sp.). I. Correspondence with hummingbird pollinators and the role of plant size, density, and floral morphology - Alison K. Brody (Oecologia, 1992)

Oviposition choices by a pre-dispersal seed predator (Hylemya sp.). II. A positive association between female choice and fruit set - Alison K. Brody (Oecologia, 1992)

Variance in thermoregulatory efficiency between immature and adult bushy-tailed woodrats (Neotoma cinerea) - T. Wangchuck (1992)

Factors correlated with the productivity and distribution of temperate ants of the genus Myrmica - C. R. Nufio (1992)

Can Speyeria mormonia detect nectar in a floret? A study in butterfly foraging behavior - V. Iyengar (1992)

Relative success of self and outcross pollen comparing mixed- and single-donor pollinations in Aquilegia caerulea - A. M. Montalvo (Evolution, 1992)
Flowers frequently receive both self (S) and outcross (OC) pollen, but S pollen often sires proportionally fewer seeds. Failure of S pollen can reflect evolved mechanisms that promote outcrossing and/or inbreeding depression expressed during seed development. The relative importance of these two processes was investigated in Aquilegia caerulea, a self-compatible perennial herb. In the field I performed single-donor (S or OC) and mixed-donor (S plus OC) pollinations to compare the relative success of both pollen types at various stages from pollen germination to seed maturity. Single-donor S pollinations produced significantly fewer and lighter seeds (x decrease = 12% and 3%, respectively) than OC pollinations. Abortion rates differed by an average of 38% whereas fertilization rates differed by only 5%, indicating that most differences in seed number arose postzygotically. This suggests that inbreeding depression was responsible for most failure of S pollen. One prezygotic effect measured was that 10% fewer S than OC pollen tubes reached ovaries after 42 hr, suggesting S pollen might fertilize proportionately fewer ovules after mixed pollination. Using allozyme markers, I found mixed-donor pollinations produced significantly more and heavier outcrossed than selfed seeds. However, the proportion of selfed seed, fertilized ovules, and aborted seeds for mixed-donor fruits were each predictable from pollen performance in single-donor fruits, suggesting that differential paternity is best explained by inbreeding depression during seed development. Even given these similarities between mixed- and single-donor fruits in the relative performance of S and OC pollen, both individual seed weight and seed set were significantly higher in multiply-sired fruits.

The natural revegetation of the old volleyball court: is neglect sporting in the restorative field? - E. D. Andrews; H. Dickinson (1992)

Time-place learning in Tamias minimus - M. Winterrowd (1992)

Global Warming and Biodiversity - J. Harte; M. S. Torn; D. Jensen (1992)

Community structural and compositional variability on a microsite basis - G. Merrill (1992)

The spatial scale of genetic differentiation in a hummingbird-pollinated plant: comparison with models of isolation by distance - Diane R. Campbell; J. L. Dooley (American Naturalist, 1992)
We examined patterns of genetic differentiation at isozyme loci in natural populations of Ipomopsis aggregata, for which distances of gene flow had been previously estimated. Using genetic neighborhood areas based on direct estimates of gene flow to define subpopulations, we found that FST values (the inbreeding coefficient of a subpopulation relative to the total population) were consistently positive but small. Allele frequencies were spatially autocorrelated at distances of less than 5 m only. Both measures of genetic structure indicate some isolation by distance but less than predicted by current population genetics theory. Subpopulation size derived from realized gene flow estimates from paternity analysis produced a slightly better fit to theory than did using estimates from tracking pollen dispersal to stigmas. Discrepancies between observation and theory may also arise from other sources including occasional long-distance gene flow that is difficult to observe.

Factors in recovery of subalpine vegetation studied (Colorado) - C. G. Curtin (Restoration and Management Notes, 1992)

Genes in Ecology - M. E. Feder; W. B. Watt (1992)

Plant size, geitonogamy, and seed set in Ipomopsis aggregata - T. J. De Jong; Nickolas M. Waser; Mary V. Price; R. M. Ring (Oecologia, 1992)

the Unique Value of Biological field stations - J. C. Johnson (Bios, 1992)

The effect of herbivory on nectar production of Ipomopsis aggregata - S. Griggs (1992)

Variation in sex allocation and floral morphology in Ipomopsis aggregata (Polemoniaceae) - Diane R. Campbell (American Journal of Botany, 1992)
Intrapopulational variation in biomass allocation to male vs. female function was quantified for the hermaphroditic plant Ipomopsis aggregata in terms applicable to sex allocation models. The proportions of flower biomass put into the corolla and calyx averaged 0.59 and 0.20 and were relatively constant across plants. The proportions in the stamens and pistil averaged 0.13 and 0.08, with considerable variation among plants. Phenotypic gender at the time of flowering ranged from 0.34 to 0.77 female. Pistil dry weight was correlated with stigma exsertion. Stamen weight was correlated with corolla width, which influences male pollination success, and was also correlated with anther position and pollen production. Female reproductive success as estimated by seeds per flower showed no detectable relationship with initial allocation of biomass at the time of flowering, but decreased in accelerating fashion with the proportion of final biomass including seeds that was allocated to male function.

Anthophilous fly distribution across an elevation gradient - C. A. Kearns (American Midland Naturalist, 1992)
-Flower-visiting Diptera are abundant in montane and Arctic areas. This research, conducted on the western slope of the Colorado Rocky Mountains: (1) characterizes the predominant anthophilous fly taxa in comparison with other high-elevation and highlatitude sites; (2) examines changes in fly abundance with elevation, and (3) examines the potential of flies as pollinators by examining quality and quantity of pollen loads. Flies collected from 66 flowering species were identified to species to produce a data base containing taxonomic information, elevation and floral records. Malaise trap censuses were conducted in three elevational zones. Pollen carried by flies and pollen in their guts were quantified and examined to determine the number of plant species represented. Proportional representation of dipteran families changed in a similar manner in different mountain systems and the Arctic. The predominance of flies on flowers at high elevations appears to be due to a decrease in representation of other orders of insects. Most fly taxa fed at multiple plant species, but gut contents indicated that individual flies fed largely on a single pollen type. Total pollen loads of flies and solitary bees were similar although flies collected on Linum lewisii carried less pollen than bees.

Adaptive significance of Ipomopsis aggregata nectar production: observation and experiment in the field - R. J. Mitchell (Evolution, 1992)

Testing evolutionary and ecological hypotheses using path analysis and structural equation modelling - R. J. Mitchell (Functional Ecology, 1992)
The use of path analysis has grown rapidly in recent years, yet few studies employ recent advances in the field of structural equation modelling (SEM). Here I illustrate the capabilities of SEM for path analyses, using data from a study of hummingbird pollination. The main drawback to conventional path analysis is that the overall agreement between the path diagram (or model ) and the data is not quantified ; this also means that there is no clear way to directly compare competing models of the same system

The spatial arrangement of the alpine ant Formica neorufibarbis - A. Nguyen (1992)

On the appropriateness of performance measures for studying the evolution of metabolism - W. B. Watt (Functional Ecology, 1992)

The effects of stream water acidification on the behavior and mortality of two groups of benthic invertebrate larvae, B. bicaudatus and Hydropsychidae - T. Grenager; S. F. Raab (1992)

The Birds of North America - L. L. Calder; L. L. Calder (1992)

Ten years on an aspen branch - W. A. Calder (Natural History, 1992)

The relation between premolar wear and age in the yellow-bellied marmot, Marmota flaviventris - D. H. Van Vuren; C. M. Salsbury (The Canadian Field-Naturalist, 1992)

Sex allocation in hermaphroditic plants - J. Brunet (Trends in Ecology and Evolution, 1992)
Although the empirical evidence lags behind the theoretical development, sex-allocation theory has been quite successful at predicting trends among populations.

Interactions between two carrion beetle species: Nicrophorus americanus and Silpha lapponica - V. Bauer (1992)

Community stability in a small pond system - A. Bohonak (1992)

Sapsuckers, swallows, aspen, willow, and rot - P. R. Ehrlich; G. C. Daily (American Birds, 1992)

A change in coyote diet in early summer 1992 - A. Brillhart (1992)

Adaptive significance of Ipomopsis aggregata nectar production: pollination success of single flowers - R. J. Mitchell; Nickolas M. Waser (Ecology, 1992)

The role of extrafloral nectaries in seed predation of Helianthella quinquenervis: life without the ant - E. D. Andrews (1992)

Distribution and abundance patterns of Polycelis coronata - A. Brillhart (1992)

Age and sex variations in homing behavior of Peromyscus maniculatus rufinus - E. Fan (1992)

How beaver ponds affect the processing of organic matter in streams - E. Fan; J. Skelton; L. Spencer; N. Vulich (1992)

Time distribution of young yellow-bellied marmots - M. J. Garcia (1992)

Foraging behavior of Ambystoma tigrinum nebulosum - H. S. Mun (1992)

Competition for pollination in two montane plants: visitation and pollen load differences in Ipomopsis aggregata and Castilleja linarifolia - G. Schwartz (1992)

Homing behavior in Peromyscus maniculatus rufinus, or, the mice came back (mostly) - J. Skelton (1992)

Does the patch effect exist in beaver ponds in Coal Creek, CO? - R. Yaksich (1992)

Resource allocation: exploring connections between foraging and life history strategies - C. L. Boggs (Functional Ecology, 1992)
Foraging determines an organism's intake of resources (water, nutrients or energy), while life-history patterns (survival, reproduction, growth) result from resource expenditure on fitness-related activities. Allocation of a limited resource pool among competing life-history traits links foraging and lifehistory strategies (Fig. 1). Although foraging, allocation and life history can be studied independently, they must be integrated in order to understand an organism's ecology and population dynamics in contrasting or variable environments (Pianka 1976; Boggs 1981; Mooney & Chiariello 1984; Gatto, Matessi & Slobodkin 1989). In particular, integration allows us to study ecological dynamics via the effects of input and output variation on the whole system through time. Allocation is arguably both the most important and least understood element in the chain from foraging to life-history strategy. The physiological processes and the life-history effects of allocation have been studied extensively, but they have generally been examined separately. For example, life-history studies have examined correlations between offspring size and number, or among reproduction, storage, maintenance and growth, but have assumed a given resource intake and utilization efficiency (e.g. Cohen 1971; Smith & Fretwell 1974; Snell & King 1977; Reznick 1985; Parker & Begon 1986; Lloyd 1987; Reekie & Bazzaz 1987a-c). Physiological studies have focused on efficiencies of resource utilization, and resultant rates of growth or reproduction, but usually do not relate the results to integrated life-history strategies (e.g. Lei & Armitage 1980; Milne 1987; Briegel 1990; Glazier 1990). Foraging studies have considered patterns of resource intake in variable environments, but generally do not address resource use, even on further foraging effort (e.g. Chapin 1980; Real & Caraco 1986; Hutchings 1988; Tuttle, Wulfson & Caraco 1990). Here I argue that these three sorts of studies must be blended and expanded if we are to understand life-history strategies in variable resource environments. Much life-history and resource allocation work has recently focused on the evolution of specific strategies, for which an understanding of the underlying

Sorex preblei from the Black Canyon, First Record for Colorado - Charles A. Long; Robert S. Hoffmann (The Southwestern Naturalist, 1992)

Observations of a high altitude population of the sage stem-galling fly Eutreta diana (Diptera: Tephritidae) and its associated parasitoids - D. J. Emlen (Journal of the Kansas Entomological Society, 1992)

On the ecology of long-tailed weasels: a pilot study - E. W. Schweiger (1992)

Quaking aspens and woody tissue rot: how does it work and how does it affect woodpecker's tree choices for sap wells and nests - G. Shair (1992)

Effects of Mt. Crested Butte sewage treatment plant on a stream ecosystem - D. Gaul; B. Heese (1992)

Ventilatory and metabolic dynamics during entry into and arousal from torpor in Selasphorus hummingbirds - T. Bucher; M. Chappell (Physiological Zoology, 1992)

Seasonal changes in hormone-sensitive and lipoprotein lipase mRNA concentrations in marmot white adipose tissue - B. E. Wilson; S. Deeb; G. L. Florant (American Journal of Physiology, 1992)
White adipose tissue (WAT) and plasma samples were obtained from yellow-bellied marmots (Marmota flaviventris) throughout the year. Mean plasma triacylglycerol (TG), free fatty acids (FFAs), and glycerol were determined. There was a clear increase in FFAs and decrease in mean TG and glycerol during the hibernation period when animals were fasting, suggesting increased lipolysis. RNA was isolated from WAT biopsies at four times in the year: spring, summer, fall, and winter. There were significant changes in the relative levels of mRNA for lipoprotein lipase (LPL) and hormone-sensitive lipase (HSL) during the body mass cycle of the marmot. The relative levels of LPL mRNA are high during the mass gain phase of the year and that of HSL mRNA are high during the fasting period when endogenous lipid is utilized. These results suggest that the genes for LPL and HSL are regulated seasonally to control the adipose mass depot in marmots.

Eggs, enzymes, and evolution - natural genetic variants change insect fecundity - W. B. Watt (Proceedings of the National Academy of Sciences, 1992)
Phosphoglucose isomerase genotypes in the butterfly Colias differ dramatically in biochemical properties. These differences were evaluated earlier, using metabolic network theory, to predict, successfully, their effects on glycolytic metabolism and hence on Colias flight capacity and several consequent fitness components in the wild. Female egg-laying, not previously studied, also depends on flight, so female fecundity is now predicted to differ among these genotypes. An experimental design incorporating the thermal ecology of Colias confirms these predictions in a cool habitat. Thus female fecundity differences among animal enzyme polymorphs have now been found. Quantitative reconstruction of the selection regime for phosphoglucose isomerase genotypes in Colias can now begin. The most heat-stable genotypes are the least fecund, suggesting that global warming, if it occurs, may have severe impacts, through population genetics, on demography of thermally sensitive creatures.

Effects of altered aquatic ecosystems on the surrounding floral community - V. Bauer (1992)

Changes in herbivore levels across a hybrid zone between Ipomopsis aggregata and I. tenuituba - T. A. Forbis (1992)

ArctoLemania: Not the effects of plant-animal mutualisms - D. Goldman; G. Schwartz (1992)

Effects of Resource Distribution on Animal-Plant Interactions - A. E. Weis; Diane R. Campbell (1992)

The effect of global warming on soil mesofauna - A. Rawa (1992)

COOPERATIVE RIVERFRONT PLANNING: THE COLORADO RIVER, GRAND JUNCTION, COLORADO - Katherine M. Portner (Canadian Water Resources Journal, 1992)
Abstract The Colorado River, the largest river system in the western United States stretches from the headwaters in Rocky Mountain National Park in Colorado to Mexico. This mighty river evokes strong feelings and images to many people. Rich in history, it offers a haven for outdoor enthusiasts as well as for wildlife. Unfortunately, this image of the majestic river does not hold true for the segment running through Grand Junction, where the Colorado (formerly known as the Grand) and the Gunnison Rivers meet. Once the "lifeline" of the community, the river had become a neglected and forgotten resource, with its banks being lined with salvage yards and other undesirable industrial uses.In 1985 the community embarked on an ambitious project to reclaim the Colorado River corridor. The appointed Riverfront Commission's goals are to maximize recreational use and public access, preserve and rehabilitate the wildlife and riparian habitat along the river, and promote the reclamation of the river as a source of community pride and economic revitalization for the Grand Valley.The success of the project to date can be attributed to the coordinated effort by many local state and federal agencies, as well as wide spread community support from a variety of diverse interests.

Ecology and Evolution of Plant Reproduction: New Approaches - B. A. Thomson; B. A. Thomson (1992)

Banner petal color change and pollination in Lupinus argentius - J. L. Barker (1992)

Perceived risk of predation: Tamias minimus - P. Berning (1992)

Aquatic invertebrate colonization on moss substrates in a mountain valley river - D. M. Massart (1992)

Natural recovery of a mineral mine damaged ecosystem - L. Salomon; J. Heckman (1992)

Geranium richardsonii: sexuality and pollination dynamics of a gynodioecious species - F. C. Scales (1992)

Control of Pyrethroid Resistant Colorado Potato Beetle, Grand Forks, North Dakota, 1991 - David M. Noetzel; Michele Ricard; Laura Heuser; Roger Hansen (Insecticide and Acaricide Tests, 1992)
Abstract This experiment was located on the Red River Valley Potato Growers Research farm in Grand Forks, ND. The field was planted on 28 May using cut A-size 'Norchip' certified seed. Plots were four rows, 0.9 m wide, 7.6 m in length, with a 1.5 m fallow aisle at the end of each plot. Plots were arranged in a randomized complete block design with 4 replicates. Soils at this site were Bearden silt-loam and moisture was adequate at planting. Soil systemics were applied just as the potato plants were emerging (21 Jun). Foliars were applied in 2 1 of total material per 0.0088 ha on 27 Jun, 5, 10, 19, and 25 Jul. Asana XL .66 E was combined i with the first treatment of each biological (i.e., Trident II, MYX-1806). Karate 1 E was combined with Trident II and MYX-1806 each time the biological was used. In this case a reduced dosage of each was applied. Monitor 4 E was applied, as needed, following the appropriate predetermined number of biological treatments. Percent defoliation was estimated on 19 Jul.

Integration of disturbed ecosystems in areas of high altitudes - L. Villa (1992)

Niche overlap and the potential for competition and intraguild predation between size-structured populations - S. A. Wissinger (Ecology, 1992)
Many populations are heterogeneous collections of different sizes or stages of conspecifics. Existing overlap indices do not account for the size—/stage—structured nature of these populations. In this paper I present new overlap indices that use information about the sizes of individuals that co—occur in time and space to predict the potential for interactions in size—structured guilds. An index of the opportunity for competition (IOC) calculates the frequency with which similar size classes of two species encounter each other, whereas an index of the opportunity for intraguild predation (IOP) calculates the frequency of encounters among disparate size classes of the same two species. To illustrate that these indices are more appropriate for size—structured populations than conventional indices, I calculated overlap, IOP, and IOC for all species pairs in a diverse assemblage of dragonfly larvae. The new indices revealed size—specific patterns of overlap that were not detected by the conventional index, including that (1) some species with high overlap values should interact mainly as competitors, others mainly as intraguild predators, and many as both competitors and predators, (2) subtle differences in phenology and/or size—specific shifts in habitat distribution can lead to the potential for asymmetric interspecific interactions, (3) some species with low pairwise IOP and IOC values are nonetheless vulnerable to the effects of diffuse competition or intraguild predation, (4) seasonal segregation reduces competitive overlap but at the same time increases the opportunity for intraguild predation. The indices are general in form and should be useful for analyzing distributional data for any size—structured assemblage in which the type and intensity of interaction varies as a function of relative size.

Factors influencing host plant range in two lycaenid butterflies - D. B. Carey (1992)

Fluctuation in a Rocky Mountain population of salamanders: anthropogenic acidification or natural variation? - S. A. Wissinger; H. H. Whiteman (Journal of Herpetology, 1992)
We monitored the demographics of the salamander Ambystoma tigrinum nebulosum as part of a community-wide study on the effects of acidification in sub-alpine (elevation 3600 m) ponds in central Colorado. A decline in A. t. nebulosum at this site from 1982 to 1988 has been hypothesized to result from embryonic mortality during a pulse of acidity that accompanies snowmelt in spring. Since 1988 we have monitored salamander population size, reproduction, and recruitment, and compared survival and individual growth rates among ponds which differ five-fold in acid-neutralizing capacity (ANC)

Ski runs and avalanche slopes: response to periodic natural and human disturbance - D. Thomson (1992)

Genetic diversity, disease incidence, and pathogen-mediated selection in apomictic Arabis (Brassicaceae) - B. A. Roy (1992)

Factors affecting oxygen consumption in wild-caught yellow-bellied marmots (Marmota flaviventris) - Kenneth B. Armitage; C. M. Salsbury (Comparative Biochemistry and Physiology, 1992)
It is suggested that basal metabolic rate is not an appropriate measure of the metabolic activity of free-ranging animals because basal metabolism is a stage on a food-deprivation curve.

Optimal prey size in dragonfly larvae (Odonata: Anisoptera: Libellulidae) - C. Wong (1991)

Probable consequences of a cosmopolitan distribution - J. Cairns (Speculations in Science and Technology, 1991)

Birding for fun: seeking sapsucker secrets - P. R. Ehrlich; G. C. Daily (American Birds, 1991)

Mechanisms of intra and interspecific interference between larval stoneflies. - B. L. Peckarsky (Oecologia, 1991)

Outcrossing distance effects in Delphinium nelsonii: pollen loads, pollen tubes, and seed set - Nickolas M. Waser; Mary V. Price (Ecology, 1991)

Biochemistry, physiological ecology, and population genetics -- the mechanistic tools of evolutionary biology - W. B. Watt (Functional Ecology, 1991)

Butterfly species composition by site - S. Christenson; J. C. Herz; R. Lyons; C. Wong (1991)

Abilities of hummingbirds to discern nectar quality from feeders - P. E. Dunlap (1991)

Behavioral response of Ambystoma tigrinum, tiger salamanders, to varying temperatures and oxygen levels - K. Horst (1991)

The effects of puddle nutrients on the life history of the Speyeria mormonia - K. Middleton (1991)

Adaptive nature of floral nectar production rate for the hummingbird-pollinated plant Ipomopsis aggregata - R. J. Mitchell (1991)

Predation risk and the community organization of montane ground squirrels and a phylogenetic test of the association between diurnal activity and gregarious behavior in mammals - R. J. Smith (1991)

The effect of quinolizidine alkaloids on oviposition preference, larval food preference, and survival and growth of Plebejus icariodes (Lycaenidae) larvae - D. Bryant (1991)

Egg predation in Dendragapus obscurus - Michaela Johnson (1991)

Effects of snowpack on the timing and abundance of flowering in Delphinium nelsonii: implications for climate change - David W. Inouye; A. D. McGuire (American Journal of Botany, 1991)
Delphinium nelsonii is an early‐blooming herbaceous perennial of montane western North America, which we studied in dry subalpine meadows in the Colorado Rocky Mountains. We examined the effects of variation in annual snowfall between 1973 and 1989 on the timing and abundance of flowering. During years of lower snow accumulation, D. nelsonii plants experienced colder temperatures between the period of snowmelt and flowering. Also, flowering was delayed, floral production was lower, and flowering curves were more negatively skewed; damage during floral development probably occurred in years of low snowfall. If climate change results in decreased mean annual snowfall for the Rocky Mountains, then the seed production of D. nelsonii will probably be adversely affected. Decreased snowfall may also indirectly lower the seed production of later‐blooming species by decreasing populations of bumblebees and hummingbirds that forage on D. nelsonii flowers. Decreased snowfall has the potential to reduce the number and relative proportions of species in the herbaceous flora in our study area.

Rock effect on plant location on talus slopes - Michaela Johnson; S. Griggs; C. Sickel; N. Bernard (1991)

Reproductive costs of self-pollination in Ipomopsis aggregata: are ovules usurped? - Nickolas M. Waser; Mary V. Price (American Journal of Botany, 1991)
In common with many cosexual angiosperms, the hummingbird‐pollinated montane herb Ipomopsis aggregata (Polemoniaceae) is likely to experience self‐pollination. Does this incur a fecundity cost even in such a highly self‐sterile (presumably self‐incompatible) species? Histological studies showed that self pollen germinates, and its tubes penetrate ovules almost as often as those of outcross pollen. Ovules penetrated by self tubes are especially likely to show milky callose occlusion 24–48 hr after pollination, and several observations suggest an association between occlusion and degeneration. Compared to flowers receiving only outcross pollen, seed set was reduced by 42% on average when self pollen was applied along with outcross, either by hand (in emasculated flowers) or by natural autodeposition (in unemasculated flowers). Reductions were statistically indistinguishable whether self pollen was applied 9 hr before outcross pollen, or at the same time. Unemasculated flowers accumulated substantial self pollen loads, and this autodeposition persisted when flowers were probed to mimic hummingbird visitation. Geitonogamy also is substantial, judging from field estimates of pollen transfer. Thus natural self pollen deposition may be sufficient to “usurp” ovules that otherwise could mature. In this light, late‐acting self‐rejection in I. aggregata seems decidedly less efficient than an early‐acting system that would block pollen germination or tube growth.

Postpollination selection, progeny performance, and the genetic basis of fitness traits in Aquilegia caerulea (Ranunculaceae) - A. M. Montalvo (1991)

Contrasts and Commonalities: Hispanic and Anglo Farming in Conejos County, Colorado - Paul Gutierrez; Jerry Eckert (Rural Sociology, 1991)
Abstract The San Luis Valley farming systems' project sought to identify improved technologies and better decision‐making capabilities for modest‐sized and limited‐resource farms. Characteristics of limited‐resource farms operated by Hispanic and Anglo families, which may or may not be associated with differential rates of social participation and/or institutional discrimination, were examined. To determine characteristics of client farms, data were collected and stratified on farm resources, farm operations, goal hierarchies, and operational management strategies. Hispanic and Anglo farmers differed significantly in several respects. Key among these differences were crop and livestock enterprise mixes and the importance of off‐farm income to households. For many farming parameters, farm size, age of farmer, and full‐time/part‐time characteristics overshadowed ethnicity as a determinant of decision‐making. However, an important subset of the farm population is composed of Hispanic farmers who operate below median farm acreage on a part‐time basis and for whom few technological developments or assistance programs are specifically designed or delivered.

Control of Colorado Potato Beetle with Natural Product Insecticides, Grand Forks, 1990 - Edward B. Radcliffe; Abdelaziz Lagnaoui; Kathy L. Flanders; Roger Hansen (Insecticide and Acaricide Tests, 1991)
Abstract Natural product insecticides used in this experiment were Bacillus thuringiensis var. san diego (MYX 1806), B. thuringiensis var. tenebrionis (Trident and BK-102) and azadirachtin (Margosan-O) from the neem tree, Azadirachta indica. Plots were planted 15 May at the Research Farm, Red River Valley Potato Growers Association, Grand Forks, N.D. Plots were 6 rows wide, 16.8 (55 ft) long, with 91 cm (36 inches) spacing between rows and 30 cm (12 inches) between plants. The two center rows of each plot were planted with certified 'Red Pontiac' seed pieces, the remaining four rows were planted with certified, B-size, 'Russet Burbank.' Plots were separated on all sides by 1.8 m (6 ft) of cultivated soil. A completely randomized plot design with 4 replications was used. Plots were scouted daily from CPB egg masses beginning 21 Jun. When egg masses were found these were flagged and checked daily for hatch. Timing of first spray application was based on egg hatch. Three basic spray schedules were used: first application at 30% hatch of flagged egg masses and subsequent application on either a 7 d or 10 d schedule, or first application at 30% hatch of all eggs (unflagged) laid on or before that sampling date and subsequent applications on a 7 d schedule. Plots were sprayed 1-3 times for each generation of CPB larvae: 29 Jun (30% hatch of flagged eggs—1st generation) 2 Jul (30% total hatch—1st generation), 5,9, 12, 16, 19 and 31 Jul (30% hatch of flagged eggs—2nd generation), 6 Aug (30% total hatch—2nd generation), 10, 13 and 14 Aug. Insecticidal sprays were applied using a tractor-mounted boom sprayer, with a single Teejet nozzle over each row. Sprays were applied in 150 liters water/ha (40 gal/ acre) at 275 kPa (40 psi). All data were collected from the two center rows of each plot. CPB larvae (small = 1st and 2nd instar, large = 3rd and 4th instar) were counted on 20 randomly selected whole plants per plot, PLH nymphs were counted on 35 mid-plant leaves per plot. Leaf loss to defoliation (by CPB) and hopperbum (injury caused by PLH) were estimated visually (by 2 individuals per sampling date) as percent foliage lost. CPB were counted on 4, 10 and 17 Jul, and 1, 8 and 17 Aug; defoliation was estimated on 10, 17 and 24 Jul, 1, 8 and 15 Aug; PLH were counted on 4, 10, 17 and 24 Jul, 1, 8 and 17 Aug; hopperbum was estimated on 1, 8 and 15 Aug. Insect data and plant injury ratings were expressed as mean insect numbers or plant injury × number of days elapsed (= Area under Curve). AUC for CPB was calculated separately for 1st and 2nd generations, and then summed. Yields were obtained 2 Oct by harvesting one center row from each plot. Two way analysis of variance was used to test for treatment differences in pest densities, plant injury and yield. The 1990 growing season at Grand Forks was characterized by severe drought from late Jun through harvest.

The impact of humans on red squirrels at Rocky Mountain Biological Laboratory - M. Philips (1991)

The use of community- and ecosystem-level end points in environmental hazard assessment: a scientific and regulatory evaluation - J. Cairns; P. V. Mccormick (Environmental Auditor, 1991)

Contest behaviour in Weidemeyers admiral butterfly Limenitis weidemeyerii(Nymphalidae): the effect of size and residency - R. H. Rosenberg; M. Enquist (Animal Behaviour, 1991)

Colorado Potato Beetle Control with Biological and Synthetic Insecticides, Pasquotank County, 1989 - Kenneth A. Sorensen; K. A. Kidd (Insecticide and Acaricide Tests, 1991)
Abstract Su perior' potatoes were planted near Weeksville, N.C. Single row plots, 6 . 1 B long with rows 1.06 m apart were replicated 4 times in a randomized complete block design. Treatments were applied using a COa pressurized sprayer with a single hollow cone nozzle (18 X) operating at 60 psi to apply 119.2 liter/ha. Treatments were applied 16 May (all) and 24 May (M-One, Trident and Trident II). Visual estimates of foliar damage and/or insect counts were made 23 May and 1 Jun. Larvae were counted on 3 hills/plot. Small larvae were assumed to be 1st and 2nd instars, and large 3rd and 4th.

Species diversity as distance increases from the edge of man-made disturbances on Mt. Crested Butte - S. Christenson (1991)

A time budget analysis: time spent foraging by two female yellow-bellied marmots - K. L. Drewes (1991)

Factors affecting corticosteroid concentrations in yellow-bellied marmots - Kenneth B. Armitage (Comparative Biochemistry and Physiology, 1991)
There was no consistent relationship between measures of population density and concentrations of corticosteroids; when a significant relationship occurred, only 22-34% of the variation was explained.

Social and population dynamics of yellow-bellied marmots: results from long-term research - Kenneth B. Armitage (Annual Review of Ecology and Systematics, 1991)

Obesity: Dietary Factors and Control - G. L. Florant; S. Ameenuddin; D. A. Rintoul (1991)

Can microbial species with a cosmopolitan distribution become extinct? - J. Cairns (Speculations in Science and Technology, 1991)

Intraventricular insulin reduces food intake and body weight of marmots during the summer feeding period - G. L. Florant; L. W. Singer; A. J. Scheurink; C. R. Park; R. D. Richardson; S. C. Woods (Physiology and Behavior, 1991)
It is suggested that during the summer when marmots are not hibernating and are actively feeding, brain insulin levels may play a role in regulating food intake.

The effect of floral abundance on feeder censuses of hummingbird populations - David W. Inouye; W. A. Calder; Nickolas M. Waser (Condor, 1991)
Numbers of Broad-tailed Hummingbirds (Selasphorous platycercus) captured each summer from 1979-1989 at the Rocky Mountain Biological Laboratory were quite variable, ranging from 115 (1981) to 348 (1989), with new birds usually outnumbering returning (previously banded) birds. Capture numbers were negatively correlated with the abundance of four species of flowers they visited, Erythronium grandiflorum, Delphinium nelsonii, Ipomopsis aggregata and Delphinium barbeyi; flower numbers were also highly variable during the study period. Since most of the captures were at feeders, these data suggest that in years with high floral abundance feeders are less attractive, while in years with low floral abundance hummingbirds with nests or territories at greater distances increase their use of the feeders. This interpretation is supported by seasonal variation in use of feeders, which is highest during the beginning and end of the season when floral abundance is lowest. Estimates of hummingbird density based on activity at feeders may thus be affected by the availability of floral food resources.

Habitat selection by stream-dwelling predatory stoneflies - B. L. Peckarsky (Canadian Journal of Fisheries and Aquatic Science, 1991)
Patterns of substrate size preference of predatory stoneflies were measured in a western Colorado, USA, stream and associations were examined between substrates and other physical and biological variables. Predatory Megarcys signata (Perlodidae) were found disproportionately on large stones that were not displaced during spring runoff. Predator densities were not consistently correlated with any other physical or biological variables measured. Prey densities were neither correlated with other physical variables nor with their own resource levels, with the exception that shredders were positively correlated with their relatively rare detrital resource. Interestingly, five prey taxa were autocorrelated, indicating that they recolonized, at similar densities, the same stones replaced in the same spots in the stream. Association analysis among the five most abundant taxa of mayfly grazers revealed that stones favorable for one grazer taxon were often favorable for others, but different grazer species rarely occupied distinctly different stones. Patterns observed suggest that predators are persistent enough to avoid negative associations with prey, yet prey taxa are mobile enough to avoid positive associations with predators. Further, habitat selection by predatory stoneflies may have evolved as a response to pressure from their own predators rather than as an adaptation for efficient prey acquisition.

A practical technique for measuring the behavior of foraging animals - R. J. Smith; J. B. Brown (The American Biology Teacher, 1991)
Research Article| April 01 1991 A Practical Technique for Measuring the Behavior of Foraging Animals Rosemary J. Smith, Rosemary J. Smith Search for other works by this author on: This Site PubMed Google Scholar Joel S. Brown Joel S. Brown Search for other works by this author on: This Site PubMed Google Scholar The American Biology Teacher (1991) 53 (4): 236–242. https://doi.org/10.2307/4449276 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Cite Icon Cite Search Site Citation Rosemary J. Smith, Joel S. Brown; A Practical Technique for Measuring the Behavior of Foraging Animals. The American Biology Teacher 1 April 1991; 53 (4): 236–242. doi: https://doi.org/10.2307/4449276 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentThe American Biology Teacher Search This content is only available via PDF. Copyright 1990 National Association of Biology Teachers Article PDF first page preview Close Modal You do not currently have access to this content.