It is suggested that bumblebees foraging for pollen may not perceive revisitations and their associated costs because they do not assess pollen returns on a per plant basis, and energetic-efficiency arguments predicting the pattern of foraging movements among plants may be inappropriate.

Climate change affects species and their interactions, resulting in novel communities and modified ecosystem processes. Through shifts in phenology and distribution, climatic change can disrupt interactions, including those between mutualists. Mutualisms influence the structure and stability of comm

Species distributions are responding rapidly to global change. While correlative studies of local extinction have been vital to understanding the ecological impacts of global change, more mechanistic lines of inquiry are needed for enhanced forecasting. The current study assesses whether the predict

A chronosequence study of permanent plots spanning 45 years on a 70-year-old subalpine earthflow in south-western Colorado suggests that it is the severe microclimate of the earthflow which is limiting further colonization of the site.

AbstractThis paper reports the results of pilot‐study efforts to develop methods to profile quartzite, a rock type to which geochemical and other sourcing techniques have only rarely been applied. The long‐term goal of the research is to fingerprint sources of quartzite in the Gunnison Basin, southw

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,

In studies of refuge use as a form of antipredator behavior, where prey hide in response to a predator's approach, factors such as foraging costs and the perceived risk in a predator's approach have been shown to influence the hiding behavior of prey. Because few studies of waiting games have focuse

Dual stable isotope analysis showed that leaf material was not the primary food for invertebrates associated with leaf packs, and processing rates for all leaf types were slow in the regulated Colorado River compared to rates reported in many other systems.

Roland C. Kufeld, James H. Olterman, David C. Bowden, A Helicopter Quadrat Census for Mule Deer on Uncompahgre Plateau, Colorado, The Journal of Wildlife Management, Vol. 44, No. 3 (Jul., 1980), pp. 632-639

Despite colonizing nearly every plant on Earth, foliar fungal symbionts have received little attention in studies on the biogeog- raphy of host-associated microbes. Evidence from regional scale studies suggests that foliar fungal symbiont distributions are influenced both by plant hosts and environm

Population characteristics of two copepod species, Diaptomus shoshone Forbes and Diaptomus coloradensis Marsh, and both interspecific and intraspecific interactions are examined. Both species vary in size among years and among several high altitude ponds in Colorado. Larger individuals with larger c

Recent studies in snowmelt-dominated catchments have documented changes in nitrogen (N) retention over time, such as declines in watershed exports of N, though there is a limited understanding of the controlling processes driving these trends. Working in the mountainous headwater East River Colorado

Climate change models often assume similar responses to temperatures across the range of a species, but local adaptation or phenotypic plasticity can lead plants and animals to respond differently to temperature in different parts of their range. To date, there have been few tests of this assumption

This article explores the levels of fragmentation and fracture patterns in archaeofaunal assemblages from the lower basin of the Colorado River (Argentina) following Outram's methodology. Remains of ungulates (guanaco) have suffered, in these assemblages, a high degree of fragmentation probably caus

• Premise of the study: Climate change threatens to alter the timing and magnitude of abiotic cues that synchronize mast flowering, such as temperature and precipitation. Climate change may therefore alter the frequency of masting, in turn affecting species in the community that use pulsed resources

In western North America, hummingbirds can be observed systematically visiting flowers that lack the typical reddish color, tubular morphology, and dilute nectar of "hummingbird flowers." Curious about this behavior, we asked whether these atypical flowers are energetically profitable for hummingbir

We measured thalli diameters of the lichen Rhizocarpon subgenus Rhizocarpon on 48 individual lobes of 18 rock glaciers and rock glacier complexes in the Elk Mountains and Sawatch Range of central Colorado. Cumulative probability distribution and K-means clustering analyses were used to separate lich

Abstract Human activity has been shown to influence how animals assess the risk of predation, but we know little about the spatial scale of such impacts. We quantified how vigilance and flight behavior in mule deer Odocoileus hemionus varied with distance from an area of concentrated human activity—

Seasonal movements of a subalpine population of metamorphic tiger salamanders, Ambystoma tigrinum nebulosum, were explored from 1990 to 1992. Metamorphic adults bred in permanent and semipermanent habitats during June of each year. After breeding, soma individuals returned to the terrestrial environ