Publications

Canopy architectures of five structurally complex forest stands and three structurally simple forest stands in southwest Oregon and the Willamette Valley, Oregon, were evaluated and quantified through crown area profiles. Mixed conifer and mixed conifer hardwood stands across a range of sites were sampled for crown widths and heights. Crown width and shape equations were derived and used...

1. The reproduction of the golden eagle Aquila chrysaetos was studied in southwestern Idaho for 23 years, and the relationship between eagle reproduction and jackrabbit Lepus californicus abundance, weather factors, and their interactions, was modelled using general linear models. Backward elimination procedures were used to arrive at parsimonious models. 2. The number of golden eagle...

No abstract available.

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...

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...

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...

I simulated the annual population cycles of Great Egrets (Ardea alba) at Lake Okeechobee, Florida, to provide a framework for evaluating the local population dynamics of nesting and foraging wading birds. The external forcing functions were solar energy, minimum air temperature, water depth, surface-water drying rate, and season. Solar input controlled the production of prey at moderate...

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...

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...

No abstract available.

A physical model was developed to explain threshold friction velocities u*t for particles of the size 60a??120 I?m lying on a rough surface in loose soils for semiarid and arid parts of the United States. The model corrected for the effect of momentum absorption by the nonerodible roughness. For loose or disturbed soils the most important parameter that controls u*t is the aerodynamic...

Mid- to late-Holocene vegetation change from a remote high-desert site was reconstructed using plant macrofossils and pollen from 9 packrat middens ranging from 0 to 5400 yr in age. Presettlement middens consistently contained abundant macrofossils of plant species palatable to large herbivores that are now absent or reduced, such as winterfat (Ceratoides lanatd) and ricegrass (Stipa...