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Publications

Below is a list of available NOROCK peer reviewed and published science. If you are in search of a specific publication and cannot find it below or through a search, please contact twojtowicz@usgs.gov.

Filter Total Items: 1300

Effect of hibernation and reproductive status on body mass and condition of coastal brown bears Effect of hibernation and reproductive status on body mass and condition of coastal brown bears

We investigated the effect of hibernation and reproductive status on changes in body mass and composition of adult female brown bears (Ursus arctos) on the Kenai Peninsula, Alaska. This information is fundamental to understanding nutritional ecology of wild brown bear populations. Six adult females handled in the fall and following spring (paired samples) lost 73 ± 22 kg (x̄ ± SD; 32 ±...
Authors
Grant V. Hilderbrand, C. C. Schwartz, C.T. Robbins, Thomas A. Hanley

Elk, beaver, and the persistence of willows in national parks: comment on Singer et al. (1998). Elk, beaver, and the persistence of willows in national parks: comment on Singer et al. (1998).

Singer et al. (1998) propose that the decline in populations of beaver (Castor canadensis) in Yellowstone National Park (YNP) has caused willow to be more vulnerable to browsing by clk (Alces alces). I do not believe that their scenario correctly characterizes the relationship between elk and willow in YNP The authors developed their hypothesis based on 2 sets of observations. One was an
Authors
R.B. Keigley

Abiotic and biotic controls of spatial pattern at alpine treeline Abiotic and biotic controls of spatial pattern at alpine treeline

At alpine treeline, trees and krummholz forms affect the environment in ways that increase their growth and reproduction. We assess the way in which these positive feedbacks combine in spatial patterns to alter the environment in the neighborhood of existing plants. The research is significant because areas of alpine tundra are susceptible to encroachment by woody species as climate...
Authors
George P. Malanson, Ningchuan Xiao, K.J. Alftine, Mathew Bekker, David R. Butler, Daniel G. Brown, David M. Cairns, Daniel Fagre, Stephen J. Walsh

Phylogeography of mitochondrial DNA variation in brown bears and polar bears Phylogeography of mitochondrial DNA variation in brown bears and polar bears

We analyzed 286 nucleotides of the middle portion of the mitochondrial cytochrome b gene of 61 brown bears from three locations in Alaska and 55 polar bears from Arctic Canada and Arctic Siberia to test our earlier observations of paraphyly between polar bears and brown bears as well as to test the extreme uniqueness of mitochondrial DNA types of brown bears on Admiralty, Baranof, and...
Authors
Gerald F. Shields, Deborah Adams, Gerald W. Garner, Martine Labelle, Jacy Pietsch, Malcolm Ramsay, Charles Schwartz, Kimberly Titus, Scott Williamson

Effects of food limitation and emigration on self-thinning in experimental minnow cohorts Effects of food limitation and emigration on self-thinning in experimental minnow cohorts

1. The theory of food-regulated self-thinning (FST) for mobile animals predicts population density (N) to be an inverse function of mean body mass (W) scaled to an exponent (b), such that N = k W−b, where k is a constant. FST also predicts energy requirements (or energy flow) to remain constant over time (termed energetic equivalence) as losses to cohorts (e.g. emigration and mortality)...
Authors
J. B. Dunham, B. R. Dickerson, E. Beever, R. D. Duncan, G.L. Vinyard

Role of brown bears (Ursus arctos) in the flow of marine nitrogen into a terrestrial ecosystem Role of brown bears (Ursus arctos) in the flow of marine nitrogen into a terrestrial ecosystem

We quantified the amount, spatial distribution, and importance of salmon (Oncorhynchus spp.)-derived nitrogen (N) by brown bears (Ursus arctos) on the Kenai Peninsula, Alaska. We tested and confirmed the hypothesis that the stable isotope signature (δ15N) of N in foliage of white spruce (Picea glauca) was inversely proportional to the distance from salmon-spawning streams (r=–0.99 and P
Authors
Grant V. Hilderbrand, Thomas A. Hanley, Charles T. Robbins, C.C. Schwartz

Effects of sample size and sampling frequency on studies of brown bear home ranges and habitat use Effects of sample size and sampling frequency on studies of brown bear home ranges and habitat use

We equipped 9 brown bears (Ursus arctos) on the Kenai Peninsula, Alaska, with collars containing both conventional very-high-frequency (VHF) transmitters and global positioning system (GPS) receivers programmed to determine an animal's position at 5.75-hr intervals. We calculated minimum convex polygon (MCP) and fixed and adaptive kernel home ranges for randomly-selected subsets of the...
Authors
Steve M. Arthur, Charles C. Schwartz

Effect of seasonal differences in dietary meat intake on changes in body mass and composition in wild and captive brown bears Effect of seasonal differences in dietary meat intake on changes in body mass and composition in wild and captive brown bears

The influence of seasonal dietary meat intake on changes in body mass and composition in wild and captive brown bears (Ursus arctos) was investigated because the importance and availability of meat to brown bear populations is currently an important management consideration in several North American ecosystems. Adult female brown bears on the Kenai Peninsula, Alaska, utilized meat...
Authors
Grant V. Hilderbrand, S.G. Jenkins, C.C. Schwartz, Thomas A. Hanley, C.T. Robbins

Radio-tracking large wilderness mammals: integration of GPS and Argos technologies Radio-tracking large wilderness mammals: integration of GPS and Argos technologies

We tested 30 prototype global positioning system (GPS) radiocollars on brown bears (Ursus arctos) over a 3-year period on the Kenai Peninsula, Alaska. Collars were of 2 design types: GPS units with an Argos (Argos Data collection and Location System) satellite uplink (n = 19) and GPS units where the data were stored on board (n = 10) for retrieval at a later date. All units also...
Authors
Charles C. Schwartz, Steve M. Arthur
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