Differential investment in offspring has been reported for many mammals, often in the context of the Trivers–
Willard model of male-biased investment, but evidence of differential investment in pronghorns (Antilocapra
americana) is largely lacking. We assessed the causes and consequences of different birth masses of littermate
fawns in a pronghorn...
Relative use by pronghorns (Antilocapra americana) of 16 range sites was studied during summer and fall of 1971 and 1972 on Hart Mountain National Antelope Refuge, an area of high desert
rangeland in south central Oregon. A Relative Use Index was developed based upon 1533 observations of pronghorns located on...
Pronghorn (Antilocapra americana) use of four playas (intermittent lakebeds) on Hart Mountain National Antelope Refuge (NAR) in south central Oregon was studied during the summers of 1974 and
1975. Percent canopy cover of playa vegetation, plant phenology, percent desiccated vegetation, soil moisture, available surface water and pronghorn use of range...
Bighorn sheep (Ovis canadensis) were not known to live on Tiburón Island, the largest island in the Gulf of California and
Mexico, prior to the surprisingly successful introduction of 20 individuals as a conservation measure in 1975. Today, a stable
island population of ~500 sheep supports limited big game hunting...
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, and pronghorn (Antilocapraamericana sonoriensis) occurred
along the coastal plains in the past [13
Hart Mountain National Antelope Refuge (HMNAR) established in 1936, is 101,000 ha in area. The refuge was grazed by domestic livestock from the 1870s until their exclusion in 1990. Just prior to removal of livestock, photopoints were taken at various riparian and wetland locations throughout the refuge to document riparian...
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/images/hartmtn-view.jpg
A view from the Hot-springs
Featured Species: Prong Horn
Antilocapra
Published May 1972. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog
Wildlife crossing structures and accompanying barrier fencing can prevent large mammals from accessing road surfaces and can significantly reduce wildlife-vehicle collisions while allowing animals to move from one side of the road to the other. Little research has been conducted on the behavioral responses of wildlife when encountering these novel...
The studies described here introduce a model for residue preservation on stone tools. They simulate stone tool manufacture in order to define parameters important for the study of DNA residues. Microscopic examination of stone tools has identified microcracks that trap DNA and protein from animal blood cells. Thorough investigation of...
To investigate the extent and causes of recent quaking aspen (Populus
tremuloides) recruitment in northern Yellowstone National Park, we measured browsing
intensity and height of young aspen in 87 randomly selected aspen stands in 2012, and
compared our results to similar data collected in 1997–1998. We also examined the
relationship...
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spp.), and
small numbers of pronghorn (Antilocapraamericana)
and moose (Alces alces). Aspen is a
Volcanic activity during the Tertiary has long been held
responsible for the deaths and subsequent fossilization of the
vertebrate populations of the John Day region in Oregon. Oreodonts
as plains or savannah dwelling ruminant herbivores, were likely to
have been subject to potential exposure throughout their lifetime
to volcanic debris...
We investigated how large carnivores, herbivores, and plants may be linked to the maintenance of native species biodiversity through trophic
cascades. The extirpation of wolves (Canis lupus) from Yellowstone National Park in the mid-1920s and their reintroduction in 1995 provided the
opportunity to examine the cascading effects of carnivore–herbivore interactions...
Mule deer (Odocoileus hemionus) populations in south-central Oregon are near their lowest levels since census efforts began in 1961. I investigated fawn survival, cause-specific mortality, and factors contributing to mortality from 2010 – 2012 to identify potential causes for the decline. I also explored pre-parturition and parturition site characteristics.
I...
The physical demands of rapid and economical running differ from the demands of fighting in ways that may prevent the simultaneous evolution of optimal performance in these two behaviors. Here, we test an hypothesis of functional trade-off in limb bones by measuring mechanical properties of limb bones in two breeds...
Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis [Beetle & A. Young] S.L. Welsh) plant communities with degraded native herbaceous understories occupy vast expanses of the western United States. Restoring the native herbaceous understory in these communities is needed to provide higher-quality wildlife habitat, decrease the risk of exotic plant invasion,...
Aldo Leopold, perhaps best known for his revolutionary and poignant essays about nature, was also an eloquent advocate during the 1930s and 1940s
of the need to maintain wolves and other large carnivores in forest and range ecosystems.He indicated that their loss set the stage for ungulate irruptions
and ecosystem...
Herein, we posit a link between the ecological extinction of wolves in the American West
and the expansion in distribution, increased abundance, and inflated ecological influence
of coyotes. We investigate the hypothesis that the release of this mesopredator from wolf
suppression across much of the American West is affecting, via...
Apex predators have experienced catastrophic declines throughout the world as a result of human persecution and habitat loss. These collapses in
top predator populations are commonly associated with dramatic increases in the abundance of smaller predators. Known as “mesopredator release,”
this trophic interaction has been recorded across a range of...
With declining populations and low calf recruitment in northeastern Oregon, much interest has been generated to study the survival rates and causes of mortality of Rocky Mountain elk (Cervus elaphus nelsoni). I investigated the causes of elk calf mortality and the effects of predation risk on birth-site selection by cow...
The 1995/96 reintroduction of gray wolves (Canis lupus) into Yellowstone National Park
after a 70 year absence has allowed for studies of tri-trophic cascades involving wolves, elk
(Cervus elaphus), and plant species such as aspen (Populus tremuloides), cottonwoods (Populus
spp.), and willows (Salix spp.). To investigate the status of this...
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hemionus), pronghorn (Antilocapraamericana), bighorn sheep (Ovis
canadensis)], but their densities were
Determining the causes of vegetation change in arid and semi-arid environments can be difficult and may involve multiple factors, including disturbance, inter-annual climatic variation, soils, effects from years past and interactions between these factors. Theoretical models describing vegetation change in these systems have generally focused on a single aspect as...
We assessed the effects of the elimination of livestock in riparian systems at Hart Mountain National Antelope Refuge in southeastern Oregon, 23 years after the removal of cattle grazing, using 64 photos taken before grazing was removed compared with later retake photos. Two methods were used for this assessment: (1)...
Quantitative real-time PCR (qPCR) assays that target the human-associated HF183 bacterial cluster within members of the genus Bacteroides are among the most widely used methods for the characterization of human fecal pollution in ambient surface waters. In this study, we show that a current TaqMan HF183 qPCR assay (HF183/BFDrev) routinely...
On the northern ungulate winter range of Yellowstone Park, willow (Salix spp.) and
cottonwood (Populus angustifolia and P. balsamifera) have increased in height and cover in
some places since the reintroduction of wolves (Canis lupus) and the subsequent changes in elk
(Cervus elaphus) behavior and population densities. However, in the...
The Lewis and Clark journals contain some of the earliest and most detailed written descriptions of a large part of the United States before
Euro-American settlement.We used the journal entries to assess the influence of humans on wildlife distribution and abundance. Areas with
denser human population, such as the Columbia...
Published May 1988. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog
We compared the historic and current geographical ranges of 43 North American carnivores and ungulates to identify large-scale patterns in range
contractions and expansions. Seventeen of the species had experienced range contractions over more than 20% of their historic range. In areas of
higher human influence, species were more likely...
Published June 1937. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog
Reintroduction of wolves to Yellowstone National Park (YNP) in 1995-96 provided a rare opportunity to observe the response of an ecosystem to the return of a top predator, including possible reversal of decades of decline of aspen, cottonwood, and tall willows suppressed by intensive herbivory on elk winter ranges. To...
Published January 2002. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog
It is critical for wildlife managers to understand the population dynamics of a harvested species, particularly for ungulates, which are a valuable wildlife resource. Due to concerns that mule deer (Odocoileus hemionus) populations in Oregon were declining, more comprehensive data on population vital rates and the factors potentially affecting them...
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...
Published February 1996. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog
Time can be a limiting constraint for consumers, particularly when resource phenology mediates foraging opportunity. Though a large body of research has explored how resource phenology influences trophic interactions, this work has focused on the topics of trophic mismatch or predator swamping, which typically occur over short periods, at small...
We compared three existing ecoregional classification schemes (Bailey, Omernik, and World Wildlife Fund) with two derived schemes (Omernik Revised and Climate Zones) to explore their effectiveness in explaining species distributions and to better understand natural resource geography in the Klamath Region, USA. We analyzed presence/absence data derived from digital distribution...
In the spring and summer of 1975 a study was conducted under natural conditions to determine whether wild adult Dermacentor andersoni Stiles would transmit Anaplasma marginale to cattle. The ticks were collected from the range pasture of Squaw Butte Experiment Station where anaplasmosis is enzootic and D. andersoni is indigenous....
The causes of natural mortality and disease in free ranging black bears, Ursus americanus, in California, Oregon, and Washington are poorly known. Life history components, such as scavenging and overlapping habitat with many species of carnivores, potentially expose bears to a wide range of infectious disease agents. To date, no...
Six standard coyote scent station index lines and one scentless control line were repeatedly sampled from May through October, 1974, on a 400 square mile study area in Central Oregon. The scent station index remained relatively constant at a mean value of 0.025 from May through mid-August; increased to a...
Seasonal wetlands in arid and semi-arid lands provide an important source of surface water in otherwise dry lands. Central Oregon's high desert, located in the Northern Great Basin (NGB) is dotted with hundreds of seasonal pools, locally called playas. The playas hold water or snow during parts of winter and...
Published March 1982. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog
The western United States has experienced large-scale degradation due to land use and land cover changes, invasion of annual grasses, and expansion of woody plants into grass and shrublands and the resultant altered fire regimes. These landscape-scale changes have coincided with declining mule deer (Odocoileus hemionus) populations, making habitat loss...
Historically fire has been the primary disturbance factor in the sagebrush-steppe. The settlement of the West by Euro-Americans, grazing by domestic livestock, and the concomitant spread of invasive species have altered the historical fire regime. Understanding the long-term vegetation structure and fuel succession of the various sagebrush-dominated communities of this...
Dispersal facilitates population health and maintains resilience in species via gene flow. Adult dispersal occurs in some species, is often facultative, and is poorly understood, but has important management implications, particularly with respect to disease spread. Although the role of adult dispersal in spreading disease has been documented, the potential...
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...
The role of orange coloration in the breeding behavior of
Gambelia wislizenii was examined in the Alvord Basin of southeast
Oregon. Behavioral observations of free ranging lizards supplemented
field experiments where I manipulated the sex and color of lizards
encountered by resident female G. wislizenii before and after they
acquired...
Female and male mammals have different behavioral strategies for maximizing their reproductive success. Pregnancy and lactation obligate female mammals to provide greater parental investment than males; thus, females compete with each other for food and space to rear their offspring, while male mammals compete with each other for female mates....
Little is known about Columbian black-tailed deer (Odocoileus hemionus columbianus) because of their elusive nature and the logistical difficulty of studying them in densely forested and mountainous terrain. The Oregon Department of Fish and Wildlife has identified fawn survival as an important gap in the current knowledge of demography and...
Natural selection, in its most basic form, is described as a process in which traitsincrease or decrease in frequency depending on their fitness, and only the trait withthe highest fitness will remain in the population. Yet, populations rarely have asingle `optimal' trait. The way natural selection maintains this observed variationwithin...
The conservation of declining desert fish species requires the identification of relations between fish population dynamics and their environments. Dynamic occupancy modeling, an approach that requires less information than traditional mark-recapture studies, may help identify important factors affecting population processes and aid desert fish conservation and restoration efforts. I used...
Esophageal fistulation, stomach content analysis, fecal analysis,
and ocular-estimate-by-plot are four of the most publicized methods
of determining the diets of large herbivores. The principal objective
of this study was to compare the relative values of each of these
methods based upon information collected from bi-fistulated (esophageal
and rumen) sheep...
Site 35JA42 represents the first protohistoric village
complex excavated in Southwest Oregon. Analyses of animal
bones recovered from the site offer the first significant
insights into human subsistence behaviors in this region.
Although the faunal assemblage is extremely fragmented,
detailed zooarchaeological analysis indicates that deer were
the primary meat resource...
Habitat for wildlife species that depend on sagebrush ecosystems is of great management concern. Evaluating how management activities and climate change may affect the abundance of moderate and high-quality habitat necessitates the development of models that examine vegetation dynamics, but modeling tools for rangeland systems are limited. I developed state-and-transition...
Heavy use of outdoor recreation areas in the United States
since World War II is endangering their quality. Demand made by a
rapidly growing population with rising personal incomes and increasing
leisure time is expected to grow 50 percent nationally and 146 percent in Oregon by 1975. In Oregon, population,...
Expansion of Juniperus occidentalis into the sagebrush steppe has resulted in significant changes in understory composition. A consequence of increased J. occidentalis dominance may be a depletion of the seed bank. The potential for depletion is problematic because a reduction in the amount of species available from the seed bank...
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 bighorn sheep (Ovis canadensis) have experienced significant declines and population extirpations due to novel pathogens such as Mycoplasma ovipneumoniae. This disease continues to limit the population restoration of bighorn sheep. Therefore, understanding the demographic consequences of pathogen presence and the risk of contact between bighorn populations and potential...
The condition of the sagebrush ecosystem has been declining in the Western United States, and greater sage-grouse (Centrocercus urophasianus), a sagebrush-obligate species, has experienced concurrent decreases in distribution and population numbers. This has prompted substantial research and management over the past two decades to improve the understanding of sage-grouse and...
End scrapers were an "all purpose" tool that have been associated with processes such as planing or shaving vegetal resources, shaping bone or antler implements, and to render hide into usable fabric. Examining end scrapers from four different archaeological sites on the North Umpqua River of southwestern Oregon provided interesting...
The Guano and Thousand-Virgin Sub-basins occupy over 1.8 million acres in Harney and Lake Counties in Oregon. The portions of the sub-basins in Nevada are not assessed in this document. Harney County Watershed Council (HCWC) watershed assessments focus on summarizing data from existing research, resource inventories, and management plans. This...
Fires affect animals mainly through effects on their habitat. Fires often cause short-term increases in wildlife foods that contribute to increases in populations of some animals. These increases are moderated by the animals’ ability to thrive in the altered, often simplified, structure of the postfire environment. The extent of fire...
The size, shape, and stability of a species’ dietary niche can both influence and reflect a variety of biological patterns, including species interactions, extinction risk, and ecosystem function. This is particularly apparent when dietary changes manifest at ecosystem and clade scales to profoundly affect macroecological and macroevolutionary trajectories. However, many...
Remote sensing techniques have long been useful in quantifying changes in ecosystems and the field of remote sensing is constantly evolving to better assess and describe changes, both spatially and temporally. In this thesis I explored the novel use of two remote sensing methods to quantify ecosystems; repeat photograph to...
Understanding the factors that contribute to or limit reproductive success is a fundamental objective of the field of ecology, providing insight into the ways ecosystems function and facilitating better management of natural resources. Behaviors that benefit offspring often increase costs to parents, and thus parents must adjust their level of...
Cultural resource inventories have identified,205 individual sites
on public land along the Lower Salmon River, Idaho. These sites
represent a rich and diverse record of the human occupation and
utilization of the river canyon during the past 10,000 years. Each
of these 205 sites contains its own unique record of...
A proposed state-and-transition model (STM) for the Deep Sand Savannah ecological site in central New Mexico was developed using historical data and expert knowledge. This STM was tested utilizing data from short and long term one-seed juniper (Juniperus monosperma (Engelm.) Sarg.) control experiments initiated in 1981 and 1985. Utilizing data...
I investigated survival, movements, home range sizes, and habitat selection of pygmy rabbits (Brachylagus idahoensis) in southeastern Oregon and northwestern Nevada from June 2005 to June 2007. I trapped 298 rabbits on four sites and fitted each with radio transmitters. More than 13,000 locations of telemetered rabbits were recorded. I...
State-and-transition models (STMs) have been successfully used to
describe ecological dynamics in woodlands, shrublands, grasslands, and several other ecosystems. Changes in vegetation and soil are measured to gauge and predict plant community dynamics within ecological states and transitions between alternative ecological states. Ecological states and their boundaries are defined by...
This analysis is the study of Oregon's wildlife resources from
the period prior to white settlement up to the present time, including
critical projections, based on present trends and expected conditions
for both human and wildlife populations in the state up to the year 2010.
Prior to white settlement Oregon...
The USDA Forest Service has an outstanding scientific resource in the 77 Experimental Forests and Ranges that exist across the United States and its territories. These valuable scientific resources incorporate a broad range of climates, forest types, research emphases, and history. This publication describes each of the research sites within...
The USDA Forest Service has an outstanding scientific resource in the 77 Experimental Forests and Ranges that exist across the United States and its territories. These valuable scientific resources incorporate a broad range of climates, forest types, research emphases, and history. This publication describes each of the research sites within...
Understanding the effects of disturbance and restoration on a species’ habitat is essential for understanding the demographic rates and population trends observed in a species. Sufficient habitat provides the space and resources required for survival and successful reproduction, such as food availability, access to water, protection from predators, protection from...
The effects of late spring defoliation on the winter forage quality of bluebunch wheatgrass
(Agropyron spicatum [Pursh] Scribn. & Smith), Idaho fescue (Festuca idahoensis Elmer) and elk sedge
(Carex geyeri Boott) and the response of wintering Rocky Mountain elk (Cervus elaphus nelsoni Bailey) to
changes in winter range forage quality...
Since the late 1880's western juniper has expanded in range and
increased in density in sagebrush-bunchgrass, riparian, and forested plant
communities of the Pacific Northwest. Succession to western juniper
woodland has been shown to reduce the productivity and diversity of the
understory component, result in concentration of soil nutrients beneath...
The rapid expansion of western juniper into neighboring plant communities during the past 130 years has caused considerable concern because of increased soil erosion, reduced stream
flows; reduced forage production; altered wildlife habitat; changes in plant community composition, structure, and biodiversity; and the replacement of mesic and semi-arid plant communities...
Archaeological excavations of the Cooper's Ferry site in the Lower Salmon River Canyon, Idaho, have revealed a stratified record of cultural occupation, spanning the late Pleistocene and early Holocene periods. The purpose of this study was to contribute to the understanding of cultural adaptive strategies represented in the archaeological record...
Greater sage-grouse (Centrocercus urophasianus) were once found in most grassland and sagebrush (Artemisia spp.) habitats east of the Cascades in Oregon. European settlement and conversion of sagebrush steppe into agricultural production led to extirpation of the species in the Columbia Basin by the early part of the 1900s, but sagebrush...
This report documents and summarizes several decades of work on sage-grouse populations, sagebrush as habitat, and sagebrush community and ecosystem functions based on the recent assessment and findings of the USFWS under consideration of the Endangered Species Act. As reflected here, some of these topics receive a greater depth of...
The use of Native American fire regimes evolved in the Klamath-Siskiyou bioregion over millennia. A mixture of Native American and Euro-American socio-cultural management has developed from adaptations to climate, topography, ecological processes, and land use practices. This research incorporates Traditional Ecological Knowledge (TEK) to partially examine the role of tribal...
A study was conducted to determine effects of year and season on diet quality of beef cattle grazing northern Great Basin rangelands from 1990 to 1993. Forage quality was high early in the growing season, then declined as seasons progressed (P<.05). Plant chemical composition was higher early in the growing...
Published May 2002. Reviewed August 2013. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog