Biomass burning associated with deforestation and land use in the Amazon, greatly contributes to emissions as well as depletion of elemental pools. We identified deforestation and pasture formation and quantified resultant burning emissions and terrestrial aboveground elemental pool losses during a period of early colonization in the vicinity of Jamari,...
The 1989 Exxon Valdez oil spill was a major perturbation of nearshore habitats of Prince William Sound, a wintering area for harlequin ducks (Histrionicus histrionicus). This research was designed to evaluate harlequin duck population recovery from the oil spill from 1995 to 1998, using a demographic approach to assess both...
The Quotient Method (QM) is used by the United States Environmental Protection Agency (USEPA) in ecological risk assessments of pesticides for nontarget organisms. The QM requires several assumptions regarding exposure and hazards of pesticides to wildlife; several of these assumptions have not been tested. During 1997-99, I conducted three experiments...
Small remnants of 'natural' habitats exist today throughout much of the world. Upland prairies in the Willamette Valley, Oregon have been nearly eliminated by conversion to agriculture and other uses. As a result, very few prairies remain and at least four butterfly species that require this habitat appear to be...
Forest managers are challenged to provide timber revenues and other resources for society while protecting and enhancing components of biodiversity that are often associated with older forests or older forest structure, such as dead wood. We examined small mammal response to timber harvest in stands 8-10 years following group-selection, two-story,...
The purpose of this study was to investigate the primary factors affecting colony size, reproductive success, and foraging patterns of Double-crested Cormorants (Phalacrocorax auritus albociliatus) nesting at East Sand Island in the Columbia River estuary, the largest colony of this species on the Pacific Coast of North America. This colony...
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...
Avian movement behavior provides insight on patterns of regional and local fidelity, habitat and resource requirements, the scale at which individuals perceive the landscape, and the relative influence of the spatial array of resources. Shorebirds (suborder: Charadrii) are a diverse and mobile group of wetland associated species. Large numbers of...
Both leave islands, or green tree retention clusters, and thinning prescriptions have been proposed as alternative silvicultural strategies designed to sustain the structural and biological diversity of managed forests. However, the relationship of the physical structure of leave islands and thinned forests to their associated microclimates, flora, and fauna remain...
The temporal and spatial variation in reproductive success exhibited by burrowing owls (Athene cunicularia hypugaea) facilitates the testing of mechanisms influencing this parameter. I predicted that food supplementation would increase reproductive success through one of two means: (1) directly, through increasing food availability and decreasing the effects of brood reduction,...
Denali National Park and Preserve (Denali) contains one of the highest densities of nesting Golden Eagles (Aquila cluysaetos) in North America. Productivity of this migratory population varies both temporally and spatially. Regardless of prey abundance, more fledglings are consistently produced at some nesting territories than others. In many raptor studies,...
The status of wild sheep in North America typifies the plight of many wildlife species in modern times: wild sheep have declined to 10-40% of their numbers during pristine times and on a global scale approximately 31% of Caprine are considered threatened or critical. As human populations and the number...
Mountain Quail (Oreortyx pictus) populations have declined in many areas of the western Great Basin during the past century. Yet the life history of this species is little known. From 1997 to 2000, I studied radio-marked Mountain Quail in Hell's Canyon in northeastern Oregon, in the Cascade Mountains of southwestern...
Most reserves fail to capture the habitat heterogeneity necessary to maintain viable populations of wide-ranging species. Methods to determine defensible dimensions of reserves and reserve networks are needed. The primary goal of this study was to develop such methods for lowland tropical forests by examining habitat- and spatial-use patterns of...
If two dams on the Elwha River are removed, the ecosystem will be open to the downstream flow of sediments and the upstream flow of marine nutrients in the form of anadromous fish. Nutrient enrichment may influence trophic dynamics of the entire ecosystem, extending beyond the aquatic boundary. I assessed...
Since their range expansion into the Pacific Northwest, anecdotal evidence suggests that northern barred owls (Strix varia varia) may be displacing northern spotted owls (Strix occidentalis caurina). My objectives were to characterize barred owl distribution and population increase in Oregon, investigate spotted owl territory performance before and after barred owl...
Two North American subspecies of Snowy Plovers (Charadrius alexandrinus) have been described: the Cuban Snowy Plover (C. a. tenuirostris) and the Western Snowy Plover (C. a. nivosus). Coastal populations of the Western Snowy Plover are listed as Threatened under the U.S. Endangered Species Act, while populations of the Cuban Snowy...
Models are commonly used to assess and predict wildlife response to management practices. Model validation is essential if managers are to use them with confidence. Fifteen forest bird-habitat relationship models were developed by biologists using data collected from private forestland in southwest Washington. These models predict species' probability of occurring...
The United States Fish and Wildlife Service currently uses fire as a management tool to improve Greater Sage Grouse (Centrocercus urophasianus Bonaparte) nesting and brood-rearing habitat at Hart Mountain National Antelope Refuge (HMNAR) in S.E. Oregon. Previous studies at HMNAR revealed use of burned areas by sage grouse throughout the...