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...
In grasslands, grazing by large ungulates can influence vegetation structure, composition, primary productivity, and ultimately, ecosystem functioning. While grazing represents a complex disturbance, grazing intensity largely determines the effects of
grazing on vegetation. Structural and compositional changes in the plant community caused by grazing could have bottom-up effects on species...
A study of the phyletic relationships among five species of
tragopans and an outgroup, the Blood Pheasant (Ithaginis cruentus), was
conducted from 1987 to 1991. Biochemical, behavioral, and external
morphologic characteristics were compared. A cladistic approach was
used to compare the behavioral, biochemical, and external morphologic
data collectively, as different...
Caspian terns (Hydroprogne caspia) and double-crested cormorants
(Phalacrocorax auritus) nest in large colonies on East Sand Island in the Columbia
River estuary, the largest known colonies for the two species in the world. Both
species of piscivorous colonial waterbirds have been identified as predators with a
significant impact on the...
Reintroduction programs are increasingly being used to save animals from extinction and aid in their recovery. The California Condor (Gymnogyps californianus), one of the most endangered birds in the world, is a remarkable example of how reintroduction programs can help rapidly increase a species' population numbers and range following a...
The effects of prescribed burning on the abundance, species
composition, and reproduction of small mammals were studied over a
one year period. Two burn areas were studied, one in sagebrush/
bunchgrass and one in cheatgrass. The short-term effects were
studied using monthly mark-recapture trapping on two treatment and
two control...
Although widely studied in many portions of North America, little is known about the specific habitat requirements of mallard ducks (Anas platyrhynchos) during the breeding season in western Oregon. I radio-marked 72 female mallards in the Willamette Valley of Oregon in March-April 1995-96 to document wetland habitat selection during pre-nesting...
The ecology of female Great Basin Canada geese (Branta
canadensis moffitti) and their broods was studied during the rearing
seasons of 1983 and 1984 on the Columbia River in southcentral
Washington. The movements and activities of 41 adult female geese,
marked with radio-transmitters, and their broods were monitored.
Adult female...
Shrews of the "Sorex vagrans species complex" were classified into
nine taxa on the basis of morphologic and morphometric analyses of
2,299 specimens from Washington, west of the Cascade Mountains in
Oregon, and in the Coast Ranges of California. In Washington, Sorex
monticolus setosus and S. m. obscurus occur west...
In contrast with other Odocoileus species, Columbian black-tailed deer (Odocoileus hemionus columbianus) population dynamics are not well understood throughout the species’ range. Concerns over apparent long-term population declines have prompted efforts to fill basic knowledge gaps including estimates of vital rates (fecundity, recruitment and survival) and cause-specific mortality. The Oregon...