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Selection of microsites by grizzly bears to excavate biscuitroots (Lomatium cous) Selection of microsites by grizzly bears to excavate biscuitroots (Lomatium cous)

Roots of the biscuitroot (Lomatium cous) are a common food of grizzly bears (Ursus arctos horribilis) in drier parts of their southern range. I used random sampling and locations of radiomarked bears in the Yellowstone ecosystem to investigate the importance of mass and starch content of roots, digability of the site, and density of plants relative to selection of sites by grizzly bears...
Authors
D.J. Mattson

Sustainable grizzly bear mortality calculated from counts of females with cubs-of-the-year: An evaluation Sustainable grizzly bear mortality calculated from counts of females with cubs-of-the-year: An evaluation

Unduplicated counts of female grizzly bears Ursus arctos horribilis with cubs-of-the-year are currently used to estimate minimum population sizes used, in turn, to calculate allowable (assumed to equal sustainable) mortality for grizzly bear populations in the contiguous United States of America. This calculation assumes that unduplicated counts are an unbiased and accurate indicator of...
Authors
David J. Mattson

DDE still high in white-faced ibis eggs from Carson Lake, Nevada DDE still high in white-faced ibis eggs from Carson Lake, Nevada

White-faced Ibis (Plegadis chihi) eggs collected in 1996 at Carson Lake, Nevada, showed no decrease in p,p′-DDE (DDE) concentrations from levels in 1985 and 1986 which is contrary to DDE patterns shown for most avian species. An estimated 40-45% of the population was adversely affected by DDE in 1985, 1986, and 1996 with a probable net loss of about 20% of the expected productivity. One...
Authors
Charles J. Henny

Productivity of golden eagles wearing backpack radiotransmitters Productivity of golden eagles wearing backpack radiotransmitters

We examined the association between the presence of backpack radiotransmitters and Golden Eagle (Aquila chrysaetos) reproduction (percentage of occupied territories producing young, and number of nestlings produced) over three years. The association between radio-tagging and nesting success and the number of nestlings produced varied significantly among years. A negative association with...
Authors
J.M. Marzluff, M.S. Vekasy, Michael N. Kochert, Karen Steenhof

Population identification of western hemisphere shorebirds throughout the annual cycle Population identification of western hemisphere shorebirds throughout the annual cycle

Identification of relationships among geographically distinct populations of migratory species can provide an understanding of breeding and natal philopatry, migration pathways, and population mixing during winter. We used random amplified polymorphic DNA (RAPD) analyses to search for markers specific to difficult‐to‐differentiate shorebird species (e.g. long‐billed dowitcher Limnodromus
Authors
Susan M. Haig, C. L. Gratto-Trevor, Thomas D. Mullins, M. A. Colwell

The scientific bases for preservation of the Mariana crow The scientific bases for preservation of the Mariana crow

The Panel recently released the report and recommendations resulting from its work over the last six months. Although primarily focused on the Mariana Crow, the report highlights that this is a matter potentially far more serious than the preservation of the crow on Guam and Rota. The report includes major sections dealing with the need to intensify research and control activities on the...
Authors
Committee on the Scientific Bases for the Preservation of the Mariana Crow National Research Council, W.D. Duckworth, S. R. Beissinger, S.R. Derrickson, T. H. Fritts, S. M. Haig, F.C. James, J.M. Marsluff, B.A. Rideout

Spatial use and habitat selection of golden eagles in southwestern Idaho Spatial use and habitat selection of golden eagles in southwestern Idaho

We measured spatial use and habitat selection of radio-tagged Golden Eagles (Aquila chrysaetos) at eight to nine territories each year from 1992 to 1994 in the Snake River Birds of Prey National Conservation Area. Use of space did not vary between years or sexes, but did vary among seasons (home ranges and travel distances were larger during the nonbreeding than during the breeding...
Authors
J.M. Marzluff, Steven T. Knick, M.S. Vekasy, Linda S. Schueck, T.J. Zarriello

Supervised classification of Landsat thematic mapper imagery in a semi-arid rangeland by nonparametric discriminant analysis Supervised classification of Landsat thematic mapper imagery in a semi-arid rangeland by nonparametric discriminant analysis

In this article the authors used a nonparametric discriminant function in a supervised classification of Landsat Thematic Mapper satellite imagery of a ~240,000-ha semi-arid region in the Snake River Plains, southwestern Idaho. First, agriculture pixels were classified by distance from the soil baseline and water pixels by the thermal band value. Next, successive nonparametric...
Authors
Steven T. Knick, J.T. Rotenberry, T.J. Zarriello

Reproduction of black-crowned night-herons related to predation and contaminants in Oregon and Washington, USA Reproduction of black-crowned night-herons related to predation and contaminants in Oregon and Washington, USA

We studied reproductive characteristics of Black-crowned Night-Herons (Nycticorax nycticorax) at four colonies in south central Washington and one colony in north central Oregon in 1991. Nest success, adjusted using the Mayfield method, was significantly different between colonies and ranged from 12-84% to hatching and 12-73% to 14 days post-hatching. The mean number of young surviving...
Authors
L. J. Blus, Barnett A. Rattner, M. J. Melancon, Charles J. Henny

Nitrogen metabolism of sheep and goats consuming Acacia brevispica and Sesbania sesban Nitrogen metabolism of sheep and goats consuming Acacia brevispica and Sesbania sesban

We described the effects of two East African browses, Acacia brevispica and Sesbania sesban, on nitrogen metabolism of sheep and goats. The A. brevispica had a substantial amount of proanthocyanidins (condensed tannins); S. sesban did not. The browses were fed at three levels in combination with vetch (Vicia dasycarpa) and teff straw (Eragrostis abyssinica). Fecal N, N balance, and...
Authors
A. Woodward, J.D. Reed

Influence of basin-scale physical variables on life history characteristics of cutthroat trout in Yellowstone Lake Influence of basin-scale physical variables on life history characteristics of cutthroat trout in Yellowstone Lake

Individual spawning populations of Yellowstone cutthroat trout Oncorhynchus clarki bouvieri differ in life history characteristics associated with broad spatial and temporal environmental patterns, but relationships between specific life history characteristics of Yellowstone cutthroat trout and physical aspects of the environment are poorly understood. We examined basin-scale physical
Authors
Robert E. Gresswell, W.J. Liss, Gary L. Larson, Patrick J. Bartlein
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