This data package provides data on the natural abundance isotopes of nitrate from various sources, including porewater, stream, and precipitation. The overall purpose of this data package is to complement additional data streams for nitrogen cycling metrics (e.g., riverine inorganic and organic nitr

This data package provides data on the natural abundance isotopes of nitrate from various sources, including porewater, stream, and precipitation. The overall purpose of this data package is to complement additional data streams for nitrogen cycling metrics (e.g., riverine inorganic and organic nitr

A survey of approximately 60 ponds in the Gunnison Basin, Gunnison and Pitkin counties, Colorado, U.S.A., showed a cor- relation between the thermal ranges of the ponds and the life history pattern of Ambystoma tigrinum populations. Characterization of physical and biotic parameters allowed a rankin

Nectar-collecting bumblebees are hypothesized to employ rules of movement which result in the maximum net rate of energy gain (i.e., are optimal), and predicted patterns of movement are compared with field observations to support the hypothesis.

To a hummingbird, clusters of flowers on inflorescences represent patches and provide an ideal situation to test prediction of optimal patch-use. The basic question is what decision rule should a hummingbird use to decide whether or not to leave an inflorescence? The hypothesis is that hummingbirds

The pattern of movements of the bumblebees and the various properties of the plants appear to represent coevolved adaptations and the bumbles' movement patterns appear to be optimal in the sense that they result in the maximum net rate of energy gain to the bumbling.

Aquilegia elegantula Greene and A. caerulea James occur in montane and subalpine habitats in the southern Rocky Mountains of western North America. The red and yellow flowers of A. elegantula are nodding, odorless, protogynous, and secrete a concentrated (44%) sucrose nectar in the floral spurs. See

The energy dynamics of 2 colonies of yellow—bellied marmots (Marmota flaviventris) were studied in the Rocky Mountains of central Colorado in 1969 and 1970. The Intake—Rejecta and Maintenance—Production models, which included an analysis of seasonal variations in energy flow parameters, yielded simi

A system comprising 2 species of bumblebess (Bombus appositus and Bombus flavifrons) and 2 species of flowers (Delphinium barbeyi and Aconitum columbianum) in Gothic, Colorado, USA, was manipulated to determine whether resource utilization by each bumblebee species was influenced by the presence of

Factors influencing levels and rates of variation of body temperature (Tb) in montane Bufo boreas boreas and in lowland Bufe boreas halophilus were investigated as an initial step toward understanding the role of natural thermal variation in the physiology and energetics of these ectothermic animals

The claim that temperature, rather than food abundance, determines the alternative life history sequences followed by high elevation populations of A. tigrinum is substantiated.

Nocturnal drift of stream invertebrates is examined as a predator avoidance adaptation via the hypothesis that those taxa or growth stages which are large, and thus subject to intense predation relative to smaller forms, should be most strongly constrained to nocturnal drift activity. Smaller taxa o