Grape growers seeking to protect their grapes from bird depredations have no economic guidelines for selecting one or more of several control alternatives. Many growers are not aware of the cost of applying the various control techniques, nor do they know how effective these techniques are in preventing damage to...
From July 1985 to April 1987 the pelagic zooplankton community of Crater Lake, Oregon was studied to determine taxonomic structure, absolute and relative densities, and spatial and temporal distributional patterns. Samples were collected using vertically-towed zooplankton nets. The community structure consisted of two cladoceran and nine rotifer species, which were...
In 1976 and 1977 I examined three broad problems associated with the recruitment of young mallards, Anas platyrhynchos, in the Prairie Pothole Region of North Dakota. The three problems studied were: the effects of interspecific nest parasitism on production; the chronology and magnitude of total-brood loss during the brood-rearing period;...
Behavior of grizzly bears (Ursus arctos) toward people was
studied by examining hikers' reports of grizzly bear observations
and by intensively observing grizzlies in an area of Glacier National
Park that was heavily used by day-hikers. Of concern were the apparent
habituation of grizzly bears to people in the study...
Coho salmon smolts (Oncorhynchus kisutch) were transported at low and high densities. (12 and 120 g/L) for short and long periods (4 and 12 h). Because smolts can be transplanted directly to seawater, half of the fish in each treatment were transported to tanks containing seawater and half to tanks...
A theoretical framework for economic fishery management was
developed. Extensive isocline analysis of a general fishery model
yielded a detailed look at the possible equilibrium behavior of a
system that was allowed to vary in terms of the levels of its
environmental parameters, its composition, and the response functions
governing...
A herd of California bighorn sheep (Ovis canadensis californiana),
re-introduced to the area of Hell Creek on the Sheldon National
Wildlife Refuge in northwestern Nevada, was studied from 15 June 1978
to 20 August 1980.
Major vegetation and physiographic types were delineated and
described. Habitat preferences were determined from field...
Descendants of eastern cottontails from Ohio
(Sylvilagns floridanus) introduced in Benton County,
Oregon and cottontails from Ohio were sampled and
analyzed morphometrically and colorimetrically. In
general, Oregon cottontails were smaller and lighter in
color than Ohio rabbits. Introgression and interspecific
competition with the smaller and darker colored native
brush rabbit...
Complete, identified, developmental series of larval cottids
Artedius fenestralis, A. creaseri, A. meanyi, Oligocottus snyderi,
Clinocottus embryum, and C. globiceps are described for the first
time. In addition, redescriptions of four species, Artedius harringtoni,
A. lateralis, Oligocottus maculosus, and Clinocottus acuticeps
are included that provide new and comparative information on...
Harlequin ducks (Histrionicus histrionicus) were observed during
the summers of 1979 and 1980 in Sawmill Bay, northeast Prince William
Sound, Alaska. Harlequins were associated with a short, medium gradient,
non-glacial stream (Stellar Creek) also used by salmon. Although
harlequins nested along Stellar Creek, they apparently did not establish
home ranges...
Effects of habitat and season on guild structure of avian
communities were examined for islands in the estuary zone of the
Columbia River, Oregon. Bird species were classified into guilds
according to their major food item, typical foraging substrate, and
foraging behavior. Variation in community structure indices (number of
guilds,...
The relationships between avian community structure and herbicide
modification of vegetation were analyzed on early-growth clearcuts in
western Oregon that had received phenoxy herbicide treatment 1 or
4 years previously. Only minor effects of herbicide treatment were
evident 1-year after spraying, except for red adler (Alnus rubra),
which still exhibited...
Selected life history aspects of American shad, Alosa
sapidissima, collected in Lake Umatilla of the Columbia River
during 1980 and 1981 were examined and compared to other shad
populations. Mean fork lengths of adult shad captured in
1981 were 405-, 415- and 423-mm for age III, IV and V males;...
Chum salmon from different stocks were bred together in two experiments. Three stocks contributed gametes to one experiment, two stocks to another. Sibling groups of eggs, alevins, and fry were maintained in a common environment. Variability of development rates, rearing performance, susceptibility to disease, and behavioral traits was partitioned into...
The goal of this study was to better understand stream communities through a perspective that might make their structure, organization, and development more understandable. This goal was approached
through the following objectives:
1. To determine the assemblages of stream organisms and define subsystems within a stream community.
2. To explain...