One fundamental concern in conservation biology is species abundance. For many taxa, however, these data are costly to obtain via direct observation and thus limited in geographic or temporal scope. Very high-resolution satellite imagery provides a means to address these limitations and provide remotely-sensed counts of large, colonial species. We...
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Robert Michael Suryan
One fundamental concern in conservation biology is species abundance
The central Oregon coast was selected as an ideal site for wave energy
development and establishment of the Pacific Marine Energy Center (PMEC). PMEC will consist of two nearshore sites, one north (NETS) and one south (SETS) of the Yaquina River, Oregon. Our study aims to assess how the development...
Short-tailed albatrosses (Phoebastria albatrus, hereafter "STAL") migrate throughout the North Pacific, overlapping with multiple large scale fisheries. In the Bering Sea, documented bycatch of this species is a focal conservation concern, due to the fact that this species is listed as "endangered" under the U.S. Endangered Species Act. We conducted...
Populations of organisms are influenced by both top-down (predator driven) and bottom-up (environment or resource driven) effects. Seabird research has largely focused on bottom-up factors influencing reproduction, with little emphasis on top-down. Our goal was to better understand top-down impacts on colonial nesting seabirds over a range of spatio-temporal scales....
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Katie M. Dugger RobertM. Suryan
Populations of organisms are influenced by both
Year-round habitat use of marine predators provides knowledge of important marine areas throughout different life stages. Large-scale, environmental variability, both in space and time, causes changes in the behavior and distribution of marine predators that are important to quantify for conservation. In the Northern California Current System (NCCS), common murres...
Variable ocean conditions can greatly impact lower trophic level prey assemblages in marine ecosystems, with effects propagating up to higher trophic levels. Our goal was to better understand how varying ocean conditions influence diets and niche overlap among a suite of low- to mid trophic level predators. We studied the...
This thesis explores the intricate issues surrounding migration at the U.S.-Mexico border, offering diverse perspectives and insights into its drivers, consequences, and ethical dimensions. Through three comprehensive papers, this research offers a nuanced analysis of the complex dynamics influencing the migration crisis. The first examines the historical and theoretical factors...
As wolves return to their historic habitats both in Oregon and across the globe, emotions are running high between people either gladdened or disturbed by their homecoming. Prior to colonization, wolves occupied the entire Pacific Northwest alongside Indigenous peoples. However, European settlements that ultimately coalesced to form the state of...
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Robert Melchior Figueroa
As wolves return to their historic habitats both in Oregon and
Tourism is one of the largest industries in the world, and causes many cultural, environmental, and economic problems. In this thesis, I explore ethics in the field of tourism studies, and identify three ethical models used to discuss ethics in tourism, which are: business ethics, alternative tourism, and philosophical ethics....
The object of this research is to ascertain the habitat occupied by each of the three species of voles of the genus Microtus found living in Northern Benton County, Oregon.
During the spring of 1963 and 1964 an investigation of a small
mammal community was made in McDonald Forest, near Corvallis, Oregon.
The revised North American Census of Small Mammals procedure was
used, and from this census the species composition of the community
was determined. The relationships of several genera...
The object of this study was to investigate the possibilities
of tracing aggregational behavior among Bufo boreas boreas
larvae with reference to tadpole development, and to attempt to determine
what aggregational factors initiate and maintain this behavior.
Additionally, an attempt was made to determine the significance
of temperature as an...
The purpose of this study was to record on tape and to
analyze the sonagrams of the complete repertoire of the vocalizations of the Rufous-sided Towhee, Pipilo erythrophthalmus
oregonus. Meanings were assigned to a number of the calls.
Sounds of nestlings, juveniles, and vocalizations connected with
parental care were not...
In recent years, studies dealing with temperature regulation,
temperature sensitivity, and physiological responses to temperature
in lizards and other reptiles have increased tremendously. It is
notable that snakes have been largely ignored in such studies. This
no doubt is due to their less direct relationship to ancestral endotherms.
However, problems...
The investigation was conducted from January 1965 to March
1966. An intensive effort was made to obtain large numbers of animals,
as it is believed that unavailability of specimens has been the
limiting factor in the amount of research concerning this species.
Two hundred and sixty-nine animals were collected. They...
The ecology of a population of snowshoe hares, Lepus
americanus washingtonii, was studied in western Oregon from 1960
to 1962. Objectives were to obtain information to control hares,
which frequently cause damage to coniferous reproduction in the
region, and to compare the life history of this little-studied subspecies
with others....
Description of anuran larvae with the use of staging tables is
a common practice in the study of frog life-histories, but there has
been no previous description or table of Ascaphus larvae. In comparing
Ascaphus larvae to a simplified staging table for anurans it
was found that these larvae vary...
The embryonic and larval stages of the long-toed salamander,
Ambystoma macrodactylum are described from fertilization through
the development of five toes on the posterior limbs. New stage numbers
are employed in the description of the hind limb.
The eggs used in the study were obtained by the injection of
pituitary...
Experimental crosses between Rana pretiosa pretiosa Baird
and Girard and Rana cascadae Slater, resulted in viable hybrids.
Reciprocal differences at the time of fertilization are indicated. A
high level of success in producing viable hybrids can be obtained if
Rana pretiosa pretiosa is the female of the parent species, The...
With a growing emphasis on details of behavior comes an increasing
need for knowledge of natural behavior patterns. Studies
on the life history of Peromyscus maniculatus have long been available
in the literature. More recently, investigators have turned to
analyzing the behavior of some of the subspecies of P.m. in...
In the field of herpetology, most studies of homing have been
carried out with anurans and, to a lesser degree, reptiles. Studies
of orientation and navigation in urodeles have been limited to a few
brief notes and the extensive investigation of Taricha rivularis by
Twitty (1959 and 1964).
The rough-skinned...
There are essentially no publications dealing with the skin toxin
of Taricha granulosa. This study has undertaken investigations with
this toxin in an attempt to determine its potency and its effect on the
newt's potential predators.
Test solutions were made by macerating a known volume of newt
skin in a...
The western Plethodon include vandykei vandykei, v. idahoensis,
larselli, dunni,vehiculum, stormi, elongatus, and an undescribed
form referred to as the "unstriped" Plethodon. These
salamanders have been placed into three species groups: the
Vandykei group, the Vehiculum group, and the Elongatus group.
Range maps are provided and geographic variation is discussed...
The karyotypes of five species of ranid frogs were determined
from metaphase plates of bone marrow cells. The colchicine, hypotonic-
citrate, blaze-dry technique was used to obtain the plates.
Morphometric datawere obtained from the karyotypes and compared
with other species of the genus Rana.
Like most other members of the...
Dicamptodon is the single, extant genus of the
ambystomatid subfamily Dicamptodontinae. Two species, D.
ensatus (Eschscholtz) and D. copei Nussbaum are recognized.
D. ensatus is found in the forested, mountain regions of
northwestern California and western Oregon, in the Willapa
Hills and Cascade Mountains of Washington, in extreme
southwestern British...
Over 56,000 hours of locomotor activity of Taricha granulosa
were recorded using two types of low cylindrical plastic monitoring
chambers. This species shows distinct rhythms of activity under
normal day-night cycles, shortened day-night cycles, constant
darkness (DD) and constant light (LL). The rough-skinned newt is
day active and crepuscular. I...
This report summarizes the results of a field study of a population
of the Pacific mountain beaver, Aplodontia rufa pacifica, from
August 1965 through August 1967. The study site consisted of a 13. 5-
acre grid on a logged over area in the Coast Range Mountains of
Benton County, Oregon....
The breeding habits and embryonic thermal requirements of the
Cascade frog of Oregon, Rana cascadae Slater, are described. The
limits of temperature tolerance of the pre-feeding stages are from
6° to 27°C for embryos held at constant temperatures. However, for
pre-feeding embryos exposed at different developmental stages for
short durations...
To gain a better foothold on the communication system of the
avifauna, calls and songs of the American Robin (Turdus migratorius)
were recorded and analyzed using the sound spectrograph. Ten different
calls were recognized as follows: three alarm calls, an excitement
call, challenge call, contact call, two flight calls and...
Phenetic relationships in insular populations of Lacerta sicula
and L. melisellensis correspond to geologic ages of the islands in two
regions of the Adriatic Sea. Populations of L. melisellensis on older
islands are more similar to populations of L. sicula than are L. melisellensis
from younger islands, and examination of...
Analyses of sympatric and allopatric populations of Sceloporus
occidentalis and S. graciosus from central Oregon indicate a high degree
of similarity in diet. Relative abundance, the equivalent number of
equally common taxa (E), and the probability of similarity (SIMI) were
used in the analyses. Shifts in diet between populations of...
In the summers of 1973, 1974 and 1975, I investigated population
age structure and density, and behaviors relating to habitat
selection, predator avoidance and intraspecific interaction in a population
of northwestern salamanders in a lake in the Oregon Cascade
Mountains. The study was carried out by skin- and scuba-diving at...
Life history attributes and apparent distributional
patterns suggest that Plethodon dunni exists as small, semi-isolated
populations throughout its range. Isozyme and morphological
variation in this species was examined to determine
any possible geographic trends.
Starch gel electrophoresis was utilized to examine
genetic variation at 24 isozyme loci in 287 individuals...