I examined ecological relationships and mechanisms of coexistence for sympatric populations of Columbian white-tailed (Odocoileus virginianus leucurus) and black-tailed deer (Odocoileus hemionus columbianus) in Douglas County, Oregon, from September 1997 to August 1998. Horseback transects were used to describe spatial distributions, population overlap, and habitat use for both species. Behavioral...
Large burrowing owl (Aihene cunicularia) populations exist in areas of intensive agriculture in California, and pesticide exposure has been identified as a potential threat to population persistence. I evaluated breeding season use of agricultural fields by adult male owls using radio telemetry, and examined egg contaminant residues to estimate population-level...
Evaporation ponds that dispose of agricultural drainwater provide attractive habitat for waterbirds but may result in contaminant exposure that impairs reproduction. I estimated post-hatching survival and evaluated productivity estimates for American avocets (Recurvirostra americana) nesting at evaporation ponds in the Tulare Basin, California from 1991 to 1993. Avocets and Black-necked...
The California brown pelican (Pelecanus occidentalis californicus) is listed as an endangered species under the U.S. Endangered Species Act. The Recovery Plan for this subspecies outlines the need to "Assure long-term protection of adequate food supplies and essential. . .roosting. . . habitat throughout the range." I investigated the effects...
With declining populations and low calf recruitment in northeastern Oregon, much interest has been generated to study the survival rates and causes of mortality of Rocky Mountain elk (Cervus elaphus nelsoni). I investigated the causes of elk calf mortality and the effects of predation risk on birth-site selection by cow...
I measured responses of free-ranging Rocky Mountain elk (Cervus elaphus) to recreational disturbance at Starkey Experimental Forest and Range, Oregon from April to October, 2003 and 2004. Resting, feeding, and travel activities of 13 cow elk were recorded at 5-minute intervals using Actiwatch™ motion sensors. Elk were subjected to four...
I studied small-mammal communities and their response to grazing in mixed-conifer forests and oak woodlands in the Cascade-Siskiyou National Monument in southern Oregon. My objectives were to (1) compare small-mammal communities among forest types and grazing intensities, (2) identify riparian affiliated species, and (3) describe microhabitat associations. Over two years,...
Several large wildfires in southwestern Oregon during the summers of 2001 and 2002 provided the opportunity to investigate the impacts of wildfire on northern spotted owls (Strix occidentalis caurina). I used radio-telemetry and demographic surveys to describe demographic performance and habitat selection of spotted owls in the areas burned by...
I investigated survival, movements, home range sizes, and habitat selection of pygmy rabbits (Brachylagus idahoensis) in southeastern Oregon and northwestern Nevada from June 2005 to June 2007. I trapped 298 rabbits on four sites and fitted each with radio transmitters. More than 13,000 locations of telemetered rabbits were recorded. I...
Since the early 1990s, declines in northern spotted owl (Strix occidentalis caurina) populations have been documented through extensive field surveys and range-wide demographic analyses. Although loss of late-successional forest has been credited as the primary cause for spotted owl population declines, environmental variation has also been shown to influence vital...
Northern Spotted Owls (Strix occidentalis caurina) inhabit productive forests that historically supported frequent, large, variable-severity fires in the Klamath province of southwestern Oregon occur in complex. The potential for high-severity wildfire remains high throughout this region, so remaining spotted owl habitat is at risk. An adaptive management approach to fire...
I assessed potential barriers to dispersal using homing tendency and investigated the movements and settlement site selection of pygmy rabbits (Brachylagus idahoensis) after short distance translocations in southeastern Oregon from June – December 2008. I captured, radio marked, and translocated 59 pygmy rabbits 1-2 km across landscapes with (1) continuous...
