The overall goal of this study was to identify multiple scales of habitat use and habitat electivity by redband/steelhead trout and define the limiting factors affecting the distribution patterns of this species during summer flows.
The main objective in chapter 2 was to identify the most important habitat associations that...
The dissertation introduces community-based adaptive watershed management (CAWM) as a holistic conservation framework. The CAWM
framework integrates social and ecological suitability to achieve conservation outcomes. The core theoretical concepts consist of adaptive management, adoption-diffusion,
symbolic interactionism, community-based conservation, spatial analysis and watershed management. The CAWM framework is applied to the...
Northern Spotted Owls (Strix occidentalis caurina) are a long-lived forest owl and range-wide declines in their numbers have resulted in the species being listed as threatened under the endangered species act. While many studies have been focused on population trends and reproductive performance of Spotted Owls from different age-classes, none...
Northern anchovy (Engraulis mordax) are a dominant forage fish in the California Current large marine ecosystem (CCLME). However, little is known about northern anchovy abundance, distribution, age structure, or population fluctuations relative to ocean conditions in the eastern boundary upwelling system off the U.S. West Coast. This thesis includes three...
Riparian vegetation (trees > 10 cm dbh), woody debris (> 10 cm diam, > 1 m long), channel, and landform characteristics were inventoried in mature (80-150 yrs) and old-growth riparian areas (>250 yrs) selected from small tributaries of the Coos and Coquille River basins in southwestern Oregon. Basal area of...
This study was undertaken to determine if strontium chloride could be used to create a trans-generational otolith mark in steelhead (Oncorhynchus mykiss). I completed two strontium injection trials and a survey of juvenile steelhead from various steelhead hatcheries. The two trials measured Sr:Ca ratios in otoliths in response to injections...
Riparian areas in the arid western United States are critical ecosystems that have been severely degraded by a variety of land and water uses over the last 100 years. In this study, the composition and structure of floodplain vegetation along the Lower Owens River in eastern California was quantitatively described...
Great Salt Lake (GSL), Utah, is surrounded by 191,884 hectares of wetlands. These wetlands provide critical habitat for hundreds of thousands of breeding, migrating and wintering waterfowl each year. As the human population around GSL increases, government officials have proposed to divert more water from the Jordan, Ogden, and Bear...
Incidental bycatch in commercial fisheries has been identified as a threat to black-footed albatrosses (Phoebastria nigripes) and Laysan albatrosses (P. immutabilis). Effective long-term conservation of these albatrosses necessitates a thorough understanding of their marine distribution, which marine habitats are selected during foraging, and where they are most likely to interact...
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...
High severity fire is a historical and integral disturbance process in coniferous
forest types. Compounded disturbances such as multiple fires or post-disturbance
management activities are increasingly common, but ecological responses are not well
understood and may represent novel types of disturbances. I studied bird and small
mammal communities in the...
Results of a study of spatial and temporal utilization of a tidal river estuary by hatchery and wild juvenile salmonids
(Oncorhynchus spp. and Salmo spp,), of overlap in food habits of hatchery and wild juvenile salmonids, and of size and relative
abundance of associated fish species are reported in this...
Under laboratory conditions, elevated temperatures accelerated production of gametes. However, when conditioning for spawning at elevated temperatures was
initiated early in the season (January-March), larval survival and number of spat collected were significantly lower than when conditioning was initiated in may or June. At elevated temperatures, broodstock oysters were fed...
Populations of coastal cutthroat trout, Oncorhynchus clarki clarki, were sampled in 16 headwater streams from logged (20-30 and 40-60 years ago) and unlogged (stand age 125-150 years) basins. Basins logged 20-30 years ago supported the widest range of mean biomass of age 1+ or older cutthroat trout (g/m2) and the...
Identification of critical habitat for all life stages of commercially exploited fish populations is critical for effective management. Despite a clear need for basic biological information on juvenile rockfish life history, there have been very few efforts to describe distribution and habitat of this life stage, particularly along the Oregon...
Land use alters the physical and biological structure of stream ecosystems and potentially alters their capacity to process nitrogen (N), an essential nutrient that has nearly doubled in abundance on the biosphere
during the past century from human activities. In this dissertation, I quantified uptake and transformation of nitrate (NO₃⁻)...
The genetic basis of adaptation is complex as many fitness-related traits are quantitative and likely influenced by multiple genes with variable effects across different selective environments. One important adaptation for anadromous Chinook salmon (Oncorhynchus tshawytscha) is the time at which individuals return to natal breeding sites within a reproductive season....
Between 1970 and 1974, data were collected on the distribution and biology of the spotted owl (Strix occidentalis) in Oregon. One-hundred and sixteen pairs and seven single birds were located. Spotted owls occurred throughout the mountains of western Oregon and on the east slope of the Cascade Range at least...
Aquatic ecological investigation is expanding to encompass considerations of
multiple scales across large landscapes. Much of the analysis included in this work
focuses specifically on coho salmon (Oncorhynchus kisutch) in multiple subbasins on
the Oregon coast. Coho salmon were chosen for an investigation of spatial scales,
network connections, and life...
During the summers of 1970 and 1971 a total of 95 sea otter (Enhydra lutris) were shipped to Oregon from Amchitka Island, Alaska. The 1970 shipment consisted of 31 otter which were to be released on the southern Oregon Coast near the town of Port Orford. Two of these animals...
This study was designed to provide life history information about juvenile fall Chinook salmon, Oncorhynchus tshawytscha
(Walbaum), in a small coastal river by 1) documenting the length of residence of the juveniles throughout the river, 2) exploring several factors possibly influencing their length of residence, and 3) assessing the relative...
Frequent or lengthy predation risk can cause one of two modifications of prey feeding
behavior: 1) postponement of feeding to less risky periods, or 2) resumption of feeding
behavior despite persistent risk. North Pacific flatfishes exhibit both of these responses when confronted with temporal variation in risk, and this experimental...
I used current water management practices in central and eastern Oregon and Washington as natural experiments to quantify the effects of irrigation water withdrawals on macroinvertebrate community structure and life history strategies. Reduced discharge had direct (e.g. decreased velocity and wetted habitat) and indirect (e.g. increased conductivity and temperature) effects...
Anadromous coastal cutthroat trout Oncorhynchus clarkii clarkii may be highly dependent on estuaries, passing through them multiple times during their lifetime. However, few studies have investigated estuarine use by coastal cutthroat trout and it is often thought that estuaries serve primarily as migration corridors rather than rearing areas. We used...
Mark-recapture methods were used to examine watershed-scale survival rates of coastal cutthroat trout (Oncorhynchus clarkii clarkii) from two headwater stream networks located in the foothills of the Cascade Mountain Range, Oregon. Differences in survival were explored among spatial (stream segment, stream network [main stem or tributaries], and watershed) and temporal...
I developed a priori hypotheses and used logistic regression to model Greater Sandhill
Crane (Grus canadensis tabida) nest success in relation to weather, habitat and management variables for cranes breeding at Malheur National Wildlife Refuge (MNWR) in southeast Oregon. My primary interest was to investigate the effects of habitat conditions...
The potential for Rocky Mountain mule deer (Odocoileus hemionus hemionus)
to host exotic chewing lice (Damalinia (Cervicola) sp.) believed to cause deer hair
loss syndrome in Columbian black-tailed deer (Odocoileus hemionus columbianus),
was investigated in captive deer held in pens at E.E. Wilson Wildlife Area, Corvallis,
Oregon from March 2004...
Oregon's only remaining non-reservoir population of adfluvial bull trout (Salvelinus confluentus) is found in Odell Lake, in the headwaters of the Deschutes River. The population size is unknown, but appears to be quite small. Limited spawning and rearing habitats, combined with the effects of introduced species and other anthropogenic changes...
Wildfire is a largely terrestrial perturbation broadly recognized as an agent of disturbance and ecological change in forested biomes. Effects of post-fire conditions on biotic components of aquatic systems have been less well-documented, although hypothetically, the two are strongly connected. In fact, the influence of wildfire may be most profound...
The role of fire as a natural disturbance, its interactions with nonnative species and effects of repeated fires in the Hawaiian Islands have received little investigation. We are unsure of the role fire played in shaping forest structure and composition as well as affecting evolutionary processes of the native biota....
For many species of marine turtle the characteristics that define pelagic habitat have yet to be fully identified. A better understanding of these habitat characteristics is critical to reduce high seas fisheries interactions with turtles, especially as the status of many turtle populations has placed them on the threatened or...
Effective treatment of larval bacterial diseases is a difficult problem when
culturing ornamental fish. Oral administration of antibiotics using existing
microparticle types is not effective due to high leakage rates; furthermore, injection of
larvae is not practical. Treatment is currently limited to use of antibiotic baths, . In this
study,...
First introduced to the USA in 1958, Myxobolus cerebralis, the parasite responsible for whirling disease in salmonids, has since spread across the country causing severe declines in wild trout populations in the intermountain west. Recent development of risk assessment models used to assess the likelihood and consequences of exotic parasite...
Understanding seasonal changes in growth, survival, and movement rates is
crucial to salmonid management. These life history characteristics provide a context for
evaluation of management actions. We evaluated the life history of individually
marked Oncorhynchus mykiss gairdneri in the South Fork John Day River basin in
Northeastern Oregon. This thesis...
I studied developmental rates in a suite of temperate and tropical passerine bird species from the New World to test the hypothesis that tropical passerines exhibit slower patterns of growth and development than temperate birds. I also investigated how the expression of several developmental rates varied with life history traits...
Larval transport and retention of two endangered suckers were studied in a highly
altered lacustrine/riverine complex. The endangered populations of Lost River sucker,
Deltistes luxatus, and shortnose sucker, Chasmistes brevirostris, in Upper Klamath Lake
(UKL), Oregon are the largest remnant populations of these suckers. Downstream of
UKL, the Keno Impoundment...
Low reproductive success has been typical of high elevation populations of the Hawaiian goose (Branta sandvicensis) or nēnē. Researchers identified predation and inadequate nutrition as limiting factors. Reproductive success remained low in most years despite on-going predator control programs. I used a supplemental feeding program over two breeding seasons in...
Recently, there has been concern over the decline of the Pacific lamprey, Lampetra tridentata, in the northwestern United States. However, effective management has been impeded by data gaps in basic biology, especially in the early life stages. Consequently, in 2004 and 2005 I examined reproductive ecology, larval recruitment, and lamprey...
Anthropogenic land use alterations such as livestock grazing and fire
suppression have greatly altered sagebrush grasslands of the Great Basin,
facilitating invasion of exotic annuals, increases in woody species, and losses of
native species. Much of the current research surrounding wildland and prescribed
fire in sagebrush dominated ecosystems has focused...
Riparian areas in the Pacific Northwest provide important biotic and abiotic
features, such as down wood, moist microsites, and abundant invertebrate prey that
benefit aquatic and terrestrial amphibians. Reported high densities of amphibians from
streams and riparian areas in the Pacific Northwest highlight their importance in riparian
food webs. Amphibians...
Lahontan cutthroat trout (LCT) (Oncorhynchus clarki henshawi) are currently limited in their distribution to a patchwork of small isolated populations, the result of habitat degradation and natural variation in landscape and in-stream conditions. The objectives of this study were to determine how landscape level topographic features influence LCT distribution patterns....
Historically, least terns (Sterna antillarum) were one of the most common tern species in North America. However, population declines have resulted from direct and indirect anthropogenic pressures on their breeding and foraging habitat. Three subspecies of least terns have been described within the United States: California least tern (S. a....
Riparian areas are eco-tones where aquatically- and terrestrially-derived insect biomass is exchanged between habitats, presenting consumers with new sources of energy, and resulting in a reciprocal subsidy. The relative contribution of energy exchange and the
resulting impacts on vertebrate riparian consumers, such as fish or birds, remains poorly understood. We...
The northern goshawk (Accipiter gentilis) is a species of concern in the western United States due to its association with mature structural stage forests. I employed a use-versus-availability study design to quantify the vegetative, physiographic, and landscape variables associated with goshawk breeding habitat selection in the San Juan Mountains of...
The Northern California Current (NCC) ecosystem exhibits extreme seasonal, interannual and interdecadal shifts in the abiotic environment and shifts in primary and higher production. This variability is also apparent in the spatial structure of the ecosystem with nearshore-shelf waters (<150 m isobath) being highly productive and having a different community...
Chinook salmon (Oncorhynchus tshawytscha) display the greatest variability of return times to freshwater of all Pacific salmon. Differential return times to freshwater have segregated populations of Chinook into two broad types or runs, fall and spring, named for the time of year in which they migrate to freshwater. Migration time...
I studied small-mammal communities and their response to grazing in mixed-conifer forests and oak woodlands in the Cascade-Siskiyou National Monument in southern Oregon. My objectives were to (1) compare small-mammal communities among forest types and grazing intensities, (2) identify riparian affiliated species, and (3) describe microhabitat associations. Over two years,...
The goal of this research was to characterize thermal habitat requirements for juvenile redband steelhead trout (Oncorhynchus mykiss gairdneri) in the South Fork John Day River (SFJD), Oregon using physiological indicators of fish condition. Physiological indices of fish condition measured were whole body lipid content and heat shock proteins, specifically...
The goal of this research was to characterize thermal habitat requirements for juvenile redband steelhead trout (Oncorhynchus mykiss gairdneri) in the South Fork John Day River (SFJD), Oregon using physiological indicators of fish condition. Physiological indices of fish condition measured were whole body lipid content and heat shock proteins, specifically...
Salmonid run sizes are strongly affected by their early marine stage. Fully understanding the life history of salmonids means understanding how they interact with their marine environment and with other fishes. Changes in the biological and physical environment off the Columbia River region affects the distribution and abundance of predatory...
Seabirds are an integral component of marine ecosystems, however, because humans typically observe only snapshots of their lives at sea, our understanding of seabird foraging ecology is often limited. A more complete understanding of the ecological roles of seabirds and identification of critical foraging habitats requires the ability to follow...
Pacific rockfishes (genus Sebastes) have attracted wide scientific and public interest from an evolutionary, fishery and conservation standpoints. This dissertation addresses several hypotheses involving spatial and temporal scales of genetic change in two overfished rockfishes, darkblotched (S. crameri) and canary rockfish (S. pinniger), using statistical analyses of genetic variation within...
An acceptable microparticulate diet for marine fish larvae may be defined as an artificial diet that contains, retains, and delivers the required nutrients to support survival and growth. Factors affecting ingestion rate of prey items by fish larvae include environmental factors such as light intensity, prey/background contrast, possible chemical cues,...
I measured responses of free-ranging Rocky Mountain elk (Cervus elaphus) to recreational disturbance at Starkey Experimental Forest and Range, Oregon from April to October, 2003 and 2004. Resting, feeding, and travel activities of 13 cow elk were recorded at 5-minute intervals using Actiwatch™ motion sensors. Elk were subjected to four...
North American sagebrush (Artemisia spp.) ecosystems are suffering from
reductions in habitat extent and quality. Only about 50% of sagebrush remains
from pre-settlement conditions, and much of the remaining habitat is
fragmented or degraded by invasive species, fire suppression and overgrazing.
Sagebrush-obligate species are experiencing population declines as a result...
I examined the avian biogeography of the islands of Lago Gatun, Panama, in an effort to better understand the effects of forest fragmentation in this biodiverse region, and specifically to understand the importance of fragment isolation and the mechanism behind its effects on tropical bird distribution. I combined exhaustive surveys...
Radiotelemetry was used to study the seasonal movements and habitat use of adult westslope cutthroat trout Oncorhynchus clarki lewisi in Roberts
Creek and Rail Creek, headwater tributaries of the John Day River, Oregon,
from September 2000 to December 2001. The objectives were to (1)
describe adult cutthroat trout life history...
Recent studies of headwater streams have demonstrated their importance to overall watershed biodiversity, nutrient cycling, and energy flux. However, little attention has been paid to long-term effects of forest harvest on macroinvertebrate communities in headwater streams. This study investigated headwater stream macroinvertebrate communities in the H.J. Andrews Experimental Forest, Oregon,...
For the first objective of this thesis, we attempt to understand the role of water flow and directionality in determining steelhead (Oncorhynchus mykiss) and spring/summer and fall Chinook (O. tschawytscha) migration patterns within the Columbia River Estuary and plume by integrating recent advances in biotelemetry and environmental observation and forecasting...
Habitat loss causes a reduction in available resources for wildlife, alters the configuration of remaining habitat, and may isolate wildlife populations. White-breasted nuthatches (Sitta carolinensis) are experiencing long-term population declines in the Willamette Valley of Oregon, where they are historically associated with oak woodlands. As secondary cavity-nesters, white-breasted nuthatches may...
Previous research in South Fork Hinkle Creek suggested that coastal cutthroat trout exhibit an aggregated spatial pattern across multiple spatial scales. To evaluate the persistence of the observed abundance patterns and identify factors that affect those patterns, half-duplex passive integrated transponders (PIT-tags) were implanted in 320 coastal cutthroat trout (>...
Island systems and species are susceptible to extinction because of their small population size and an ecological naiveté from an evolutionary past lacking strong competition and predation. For example, only one-fifth of the world’s bird species occur on islands, yet more than 90% of the avian extinctions witnessed during historic...
This research was designed to broaden the understanding of how timber-harvest affects aquatic macroinvertebrates in perennial and intermittent headwater streams. This study compared emergent and benthic macroinvertebrate assemblages from 20 headwater streams in the central Oregon Coast Range that varied by harvest condition and flow duration. Through comparison of the...
The Willamette River, one of only 14 American Heritage Rivers, flows through the most densely populated and agriculturally productive region of Oregon. Previous biological monitoring of Willamette River fish detected elevated frequencies of skeletal deformities in fish from certain areas of the lower (NP [NP], rivermile [RM] 26-55) and middle...