Patch dynamics of Glaucopsyche lygdamus (Lycaenidae): correlations between butterfly density and host species diversity - D. B. Carey (Oecologia, 1994)

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

Evaluation of and alternatives to current vegetation management practices of the Crested Butte Mountain Resort - J. Sims (1994)

Toadal Recovery - B. Kelly (1994)

Queen-queen interactions in the ant species Formica neorufibarbis - J. Bejarano (1994)

Cougars and conservation biology - A. Wojtalik (1994)

The effect of pocket gopher herbivory on the limitation of aspen outgrowth - J. Yurek (1994)

Secondary Lead-Copper-Zinc Minerals from: The Titusville Mine: San Juan County, Colorado - Tom Rosemeyer (Rocks & Minerals, 1994)

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

Time and wariness in yellow-bellied marmots - M. C. Corona; Kenneth B. Armitage (Ibex J.M.E., 1994)

Evolution of alternative life histories in tiger salamanders (Ambystoma tigrinum nebulosum): a study of the cannibal morph - T. W. Sacco (1994)

Interspecific and intraspecific interactions of two coexisting montane ground squirrel species (Spermophilus lateralis and Tamias minimus) - M. Arellano (1994)

Festuca thurberi and Vicia americana - a mutualism? - J. Ruvinsky (1994)

The influence of edge effects on aquatic invertebrate diversity in the streams of the East River Valley of Colorado - J. Baldwin (1994)

Reproductive success of colonial and noncolonial female yellow-bellied marmots - D. H. Van Vuren; Kenneth B. Armitage (Journal of Mammalogy, 1994)

Follow-up study on success of varying treatment in subalpine road recovery - Philip G. Taylor (1994)

Uncompahgre Fritillary Butterfly Demographics: Response to Britten et al. - Paul A. Opler; Amy L. Seidl (Conservation Biology, 1994)
Using the same methods as Britten, my associates and I ran Pollard transects during four flight seasons at Redcloud Peak and during three flight seasons (1991-93) at Mt. Uncompahgre and found that the populations are declining precipitously, genetic analyses show low heterozygosity, and no heroic effects should be made to salvage the species.

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

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

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

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

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

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

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

Crossing distance effects on prezygotic performance in plants: an argument for female choice - Mary V. Price; Nickolas M. Waser (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

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

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

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

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

Intraguild predation and competition between larval dragonflies: direct and indirect effects on shared prey - J. McGrady; S. A. Wissinger (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.

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

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

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

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

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

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

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

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

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

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

Biological Field Stations: Opportunities for undergraduate and faculty research - Richard Alexander Smith (1993)

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

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

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

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

Proceedings of the International Symposium on Pollination in Tropics (1993)

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

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

Geitonogamy: the neglected side of selfing - T. J. De Jong; Peter G.L. Klinkhamer; Nickolas M. Waser (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.

The Effects of Environment and Culture on the Distribution of Prehistoric Dwellings at Chimney Rock Mesa, Colorado - Frank W. Eddy; Dale R. Lightfoot (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

Design and Analysis of Ecological Experiments - Richard S. Mitchell (1993)

Behavioral observations of Ochotona princeps: foraging and haypiles (1993)

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

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

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

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

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

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

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

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

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

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

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.

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

The effect of molt on oxygen consumption of yellow-bellied marmots (Marmot flaviventris) - C. M. Salsbury; Kenneth B. Armitage (Comparative Biochemistry and Physiology, 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; Randolph S. Parker; Lauren E. Hay; 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 relative role in parental care of a pair of nesting mountain bluebirds, Sialia currucoides - K. M. Wacker (1993)

Planktivore effects on zooplankton epibiont communities: epibiont pigmentation effects - S. T. Threlkeld; R. L. Willey (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.

Sublethal consequences of stream-dwelling predatory stoneflies on mayfly growth and fecundity - M. A. Penton; C. A. Cowan; C. G. Anderson; B. L. Peckarsky (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.

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)

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

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

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

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

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

Double keystone bird in a keystone species complex - N. M. Haddad; G. C. Daily; P. R. Ehrlich (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.

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

Field performance of woodburning stoves in crested butte, Colorado - Mahesh Gundappa; Dennis R. Jaasma; Robert C. Mccrillis; Mark R. Champion (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.

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

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

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

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

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.

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

Resource and pollen limitations to lifetime seed production in a natural plant population - K. J. Halama; Diane R. Campbell (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.

The effect of adult food limitation on life history traits in Speyeria mormonia (Lepidoptera: Nymphalidae) - C. L. Ross; Carol L. Boggs (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.

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)

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

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

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

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

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

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

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

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

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

Factors affecting oxygen consumption in wild-caught yellow-bellied marmots (Marmota flaviventris) - C. M. Salsbury; Kenneth B. Armitage (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.

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

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

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 - C. M. Salsbury; D. H. Van Vuren (The Canadian Field-Naturalist, 1992)

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

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

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

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

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

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

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

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

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

Resource allocation: exploring connections between foraging and life history strategies - Carol 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

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

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

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

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

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

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

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

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

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

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

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

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.

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)

Adaptive significance of Ipomopsis aggregata nectar production: pollination success of single flowers - Richard S. 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)

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

Control of Pyrethroid Resistant Colorado Potato Beetle, Grand Forks, North Dakota, 1991 - Roger Hansen; Michele Ricard; Laura Heuser; David M. Noetzel (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.

the Unique Value of Biological field stations (Bios, 1992)

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

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

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

Testing evolutionary and ecological hypotheses using path analysis and structural equation modelling - Richard S. 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

Fluctuation in a Rocky Mountain population of salamanders: anthropogenic acidification or natural variation? - Howard Whiteman; S. A. Wissinger (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)

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

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

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

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.

The spatial scale of genetic differentiation in a hummingbird-pollinated plant: comparison with models of isolation by distance - J. L. Dooley; Diane R. Campbell (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.

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

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

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

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

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

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

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

The Birds of North America (1992)

Control of Colorado Potato Beetle with Natural Product Insecticides, Grand Forks, 1990 - Kathy L. Flanders; Abdelaziz Lagnaoui; Roger Hansen; Edward B. Radcliffe (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 reality of the "switching" model, or, whatever happened to delayed gratification? - R. Lyons (1991)

Fitness value of oviposition choice in Nicrophorus americanus - R. Kramer (1991)

Temperature differences between Salix and Lathyrus habitats - S. Horne (1991)

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

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

Toxics A to Z: A Guide to Everday Pollution Hazards - C. Shirley; R. A. Schneider; C. E. Holdren; John Harte (1991)

Mud puddling by butterflies is not a simple matter - L. A. Jackson; Carol L. Boggs (Ecological Entomology, 1991)
Two sets of hypotheses based on sodium limitation have been proposed to explain the sexual dimorphism in puddling hchaviour, which suggested that males have a greater need for sodium in neuroniuscular activity because they spend a larger time in flight than females.

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

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

Effects of "nectar guides" on pollinator visitation and seed set - A. Keller (1991)

Energy reallocation in reproductive function of Ipomopsis aggregata after loss of floral tissue - S. Griggs (1991)

Variation in receptive stigma time after pollination of Aquilegia caerulea - G. Shair (1991)

Resource availability and gender variation among flowers on inflorescences of Aquilegia caerulea - S. L. Reynolds (1991)

A field test of resource depression by predatory stonefly larvae - B. L. Peckarsky (Oikos, 1991)
Experiments were conducted in two Rocky Mountain streams (Gunnison County, Colorado) to determine the context within which predatory stonefly larvae locally depress their prey populations. In feeding trials where no migration of prey (Baetis bicaudatus, Ephemeroptera) was allowed from flow-through boxes containing natural substrates, Megarcys signata and Kogotus modestus (Perlodidae) significantly depressed prey densities over 14 and 38 h, respectively. However, increasing predator density had no apparent effect on per capita predation rate. In 1984 enclosure experiments allowing prey but not predator migration, Kogotus significantly reduced total prey density and that of two relatively sedentary prey species (Cinygmula mimus, Ephemeroptera, Heptageniidae, and Zapada haysi, Plecoptera, Nemouridae) during three-day trials

Trends in Ecology - B. L. Peckarsky (1991)

Seasonal changes in CSF insulin concentrations in marmots: insulin may not be the satiety signal for fasting in winter - L. W. Singer; S. C. Woods; Shannon A. Mahan; R. D. Richardson; G. L. Florant (American Journal of Physiology, 1991)

Determinants of spatial distribution in a population of the subalpine butterfly Oeneis chryxus - D. R. Wheye; G. C. Daily; P. R. Ehrlich (Oecologia, 1991)

Yellow-bellied marmots as prey of coyotes - D. H. Van Vuren (American Midland Naturalist, 1991)
-Analysis of contents of 395 coyote (Canis latrans) scats collected for 6 yr at a subalpine locality in Colorado showed that yellow-bellied marmots (Marmota flaviventris) were a regular and frequent prey of coyotes during summer. There was no evidence that marmots were especially vulnerable to predation by coyotes during the mating season or during the time of dispersal. Marmots were most vulnerable to predation during July, for unknown reasons. Marmots apparently served as alternate prey of coyotes; marmot occurrence in scats was greatest during years when gophers, probably a preferred prey of coyotes, were infrequent in scats.

Carcass utilization by two species of carrion beetle - K. K. Agnew (1991)

A profile of persistence: territorial hummingbirds - W. A. Calder (National Geographic Research and Exploration, 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 - Richard Alexander Smith (1991)

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

The relation of resource density to exploration time in the least chipmunk - J. P. Crews (1991)

Age or pollinator manipulation causing banner petal color change in Lupinus argentus (Fabaceae) - N. Bernard (1991)

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

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

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

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

Duration of snow cover and its influence on life-history variation in yellow-bellied marmots - D. H. Van Vuren; Kenneth B. Armitage (Canadian Journal of Zoology, 1991)
We evaluated the relationship between growing-season phenology, as indicated by time of snow melt, and intrapopulation variation in reproduction and growth of yellow-bellied marmots. The time of snow melt explained significant proportions of the variation in frequency of reproduction (78%), litter size (79%), and estimated body mass of young of the year (68%), but not growth rate. We suggest that the duration of snow cover, through its effect on the length of the growing season, influences habitat quality; marmots living at localities with prolonged snow cover have a shorter season of access to food. The variation in life-history traits is attributed to phenotypic plasticity and not to local genetic variation.

Female choice in true bugs (Homoptera: Miridae) - C. Wong (1991)

The effect of floral abundance on feeder censuses of hummingbird populations - W. A. Calder; Nickolas M. Waser; David W. Inouye (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.

Effects of snowpack on the timing and abundance of flowering in Delphinium nelsonii: implications for climate change - A. D. McGuire; David W. Inouye (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.

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