Monitoring reproductive success, prey species composition, and colony size of marine birds has been proposed as a method of assessing changes in marine systems that are otherwise difficult to sample (Cairns 1987). I measured inter-annual and intra-seasonal variability in reproductive parameters, taxonomic composition of the diet, and adult body condition...
I investigated the relationship between harlequin duck (Histrionicus histrionicus) behavior and lack of recovery from the Exxon Valdez oil spill in Prince William Sound, Alaska. First, I evaluated the hypothesis that harlequin ducks in winter have little flexibility to increase foraging time in response to disturbance because they are constrained...
Recently the National Park Service has proposed raising fence heights to exclude mouflon sheep (Ovis musimon) from conservation areas at Hawai'i Volcanoes National Park. Concern over previous mortality of Hawaiian Petrels (Pterodronia sandwichensis) due to collision with fences prompted this study to quantify the potential effects of raising fence heights...
A detailed understanding of the foraging ecology of species preying upon
threatened or endangered prey may contribute to identifying and evaluating
management options to reduce predation, when such management is deemed
appropriate. In the Columbia River estuary, Caspian terns (Sterna caspia) and
double-crested cormorants (Phalacrocorax auritus) have been identified as...
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...
Understanding how wetland birds use habitat is pivotal to developing successful and
beneficial conservation strategies. Although it has been an ardent topic in forest
research for some time, how species interact with the spatial patterning of habitat
across a landscape (i.e., landscape structure) has been more or less neglected in...
Bullfrogs were introduced into Oregon in the early 1900s and have become widespread members of many wetland communities. Little is known of their ecology outside their native range, although they may play a role in the current declines observed in native herpetofauna. I analyzed the diets of 401 bullfrogs from...
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,...
Barriers to the movement of aquatic organisms can increase the genetic and spatial isolation of populations and may decrease the viability of these regional populations. Focus on culvert passage issues has increased as federal agencies attempt to inventory and replace road-crossing stream culverts that are barriers to the movement of...
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...
Dispersal is integral to our understanding of the life history and population biology of many vertebrates, but difficulties in detecting long distance movements have complicated its study. Moreover, studies of factors affecting dispersal are often unable to determine the relative contributions of variables such as nesting success, mate fidelity, and...
Wavelet analysis is an analytical and modeling tool for optimizing sampling efficiency and accuracy, particularly in the context of designing long-term, large-scale monitoring plans. As a pattern analysis method that accommodates and preserves non-stationarity, wavelet analysis provides novel visualization and analytical capabilities for increased insight into interactions between multi-scalar heterogeneous...
