R. Terry Bowyer

• Ph.D.
• Professor at Idaho State University

This comprehensive chapter covers various aspects of the biology and natural history of the Mule Deer (Odocoileus hemionus), including names, taxonomy, subspecies and distribution, descriptive notes, habitat, movements and home range, activity patterns, feeding ecology, reproduction and growth, behavior, and status in the wild and in captivity. The...

Earth has >8 billion people. Scholarly publications number nearly 7 million annually with >1 million in the life and biomedical sciences, and ≥52 professional journals specializing in conservation, ecology, or related disciplines. The challenges of applying ecological data to conservation and wildlife management can easily become overwhelming. Here...

Bighorn sheep (Ovis canadensis), and to a lesser extent mountain goats (Oreamanos americanus), historically occupied much of the mountainous rangelands of western North America. Both ungulates inhabit rugged terrain and feed on grasses, forbs, and browse. Bighorn sheep and mountain goats are widely recognized for their consumptive and non-consumpti...

Mammals are imperiled worldwide, primarily from habitat loss or modification, and exhibit downward trends in their populations and distributions. Likewise, large-bodied herbivores have undergone a collapse in numbers and are at the highest extinction risk of all mammals. Bighorn sheep (Ovis canadensis) are among those large-bodied herbivores that p...

We analyzed harvest data to test hypotheses that nearly 4 decades of effort to reduce abundance of brown bears (Ursus arctos), black bears (U. americanus) and gray wolves (Canis lupus) in an 60,542 km² area in south-central Alaska (Game Management Unit [GMU] 13) was positively correlated with moose (Alces alces) harvests in some time-lagged fashion...

Few concurrent studies exist of sympatric gray wolf (Canis lupus) and coyote (C. latrans) harvest at far northern latitudes. Moreover, no studies explicitly examine effects of concurrent harvest on phenotypes of wolves and coyotes. We documented changes in sex and age characteristics and morphology of gray wolves and coyotes harvested by hunters ne...

Reported effects of trophy harvest often are controversial. The subject is nuanced and many studies lack details necessary to place their results in context. Consequently, many studies are misunderstood or their conclusions misapplied. We propose that all dialogues about trophy hunting include a definition of how they use the term trophy, details o...

Biologists often must use incomplete information to make recommendations concerning harvest of large mammals. Consequently, those recommendations must draw on a firm understanding of the ecology of the species in question, along with selection of the most applicable population characteristics on which to base harvest-both essential components for p...

Ungulates exhibit diverse mating systems that range from monogamous pair territories to highly polygynous leks. We review mating systems and behaviors across ungulates and offer a new approach synthesizing how interacting factors may shape those mating systems. Variability exists in mating systems among and within species of ungulates and likely is...

The isotopic niche of consumers represents biologically relevant information on resource and habitat use. Several tools have been developed to quantify niche size and overlap. Nonetheless, methods adapted by spatial ecologists to quantify animal home ranges can be modified for use in stable isotope ecology when data are not normally distributed in...

We assessed body condition, diet quality (indexed by fecal nitrogen), and stress levels (using fecal glucocorticoid metabolites) in mule deer Odocoileus hemionus in southeastern Idaho, USA, during a mild (2007) and a harsh winter (2008) to evaluate spatial overlap and potential competition with North American elk Cervus elaphus. We used data from G...

Monitoring dispersal, habitat use, and social mixing of released ungulates is crucial for successful translocation and species conservation. We monitored 127 female bighorn sheep (Ovis canadensis) released in three populations from 2000 to 2009 to investigate if augmented bighorns expanded and shifted seasonal ranges, used different habitat compare...

Long-term datasets are becoming increasingly important for assessing population-and species-level responses to a changing environment. Programs that record morphological measurements of horns, antlers, and pronghorns were established in the early-to mid-20th century to collect biological information about animals that possess large horns, antlers,...

The influence of human harvest on evolution of secondary sexual characteristics has implications for sustainable management of wildlife populations. The phenotypic consequences of selectively removing males with large horns or antlers from ungulate populations have been a topic of heightened concern in recent years. Harvest can affect size of horn-...

Mammals are imperiled worldwide. Threats to terrestrial species are primarily from habitat loss or modification, and in some instances from commercial, illegal, or unregulated hunting. Terrestrial species are negatively affected throughout the tropics from deforestation. Threats to marine mammals are related to harvest, strikes in shipping lanes, p...

Surveillance for wildlife Dseases is essential for assessing population dynamics of ungulates, especially in free-ranging populations where infected animals are Dfficult to sample. Chronic wasting Dsease (CWD) is an emerging infectious Dsease of concern because of the potential for substantial negative effects on populations of cervids. Variability...

Horns, antlers, and other horn-like structures are products of sexual selection, confer reproductive advantages, and are heritable and honest indicators of individual quality. In addition to serving key biological functions, horns and antlers garner societal interest that, when combined with the powerful motivation to acquire trophy animals, likely...

The importance of trace minerals to living organisms is well established, albeit poorly studied in large, free-ranging mammals. We investigated concentrations of 11 minerals among 9 species of forage plants used by bighorn sheep (Ovis canadensis) in the Panamint Range, Inyo County, and at Old Dad Peak, San Bernardino County, California, USA. We sam...

Context Little is known about the consequences of sexual segregation (differential use of resources by the sexes outside of the mating season) for the conservation of large mammals. Roadways (i.e. the strip of land over which a road or route passes) are ubiquitous around the world, and are a major cause of wildlife mortality, as well as habitat los...

Studies in wildlife ecology often use descriptive and inferential methods that reflect characteristics of data and the practical needs of wildlife managers. The discipline generally emphasizes population rather than individual features or broader ecosystem processes; this approach is reflected in quantitative methods developed and adopted by wildli...

Animals may partially overcome environmental constraints on fitness by behaviorally adjusting their exposure to costs and supplies of energy. Few studies, however, have linked spatiotemporal variation in the energy landscape to behaviorally mediated measures of performance that ostensibly influence individual fitness. We hypothesized that strength...

Importance values (proportional use × proportional availability of a resource) add a useful component to studies of resource selection. The merit of the metric is that it identifies commonly available resources that are nonetheless critical components in the ecology of an organism. Such resources would not be identified as being selected in compari...

Ungulates use habitat with differential microclimate characteristics; therefore, fecal inputs to a particular habitat may result in vastly different rates of decomposition and nutrient release. We tested this hypothesis and conducted a 1-year decomposition experiment where we deployed fecal samples from Shiras moose (Alces alces shirasi) and subseq...

The condition of maternal female mammals greatly influences life-history characteristics of their young, but interactions between habitat and maternal condition and their combined influences on birth characteristics and survival of neonates are less well understood, especially in free-ranging populations. We monitored survival of neonatal mule deer...

We investigated influences of risk of predation by mountain lions (Puma concolor), topographic metrics at multiple scales, and vegetation, land, and snow cover on resource selection by Sierra Nevada bighorn sheep (Ovis canadensis sierrae), an endangered taxon, during winters 2002–2007, in the Sierra Nevada, California, USA. We hypothesized that tho...

We investigated how density-dependent processes and subsequent variation in nutritional condition of individuals influenced both timing and duration of sexual segregation and selection of resources. During 1999–2001, we experimentally created two population densities of North American elk (Cervus elaphus), a high-density population at 20 elk/km2, a...

We measured population abundance and density of Dall's sheep (Ovis dalli) before and during gray wolf (Canis lupus) and coyote (Canis latrans) harvest for 3 years (1998– 2000) on two similar and adjacent study sites with treatment (canid harvests) and reference (no canid harvest) in interior Alaska, USA. Between 1998 and 1999, density of Dall's she...

For long-lived species, environmental factors experienced early in life can have lasting effects persisting into adulthood. Large herbivores can be susceptible to cohort-wide declines in fitness as a result of decreases in forage availability, because of extrinsic factors, including extreme climate or high population densities. To examine effects o...

Migratory ungulates exhibit recurring movements, often along traditional routes between seasonal ranges each spring and autumn, which allow them to track resources as they become available on the landscape. We examined the relationship between spring migration of mule deer (Odocoileus hemionus) and forage quality, as indexed by spatiotemporal patte...

The selection ratio (proportional resource use divided by proportional availability) is often used by ecologists to measure the degree to which individuals and populations are selective in their food sources and habitats. Yet, confidence interval approaches for this metric are scarce and poorly evaluated. In this paper, we compare 13 methods that c...

Bighorn sheep (Ovis canadensis) often die from respiratory disease after commingling with domestic sheep. From 2000 to 2009, we observed commingling between domestic and reintroduced bighorn sheep in 3 populations in UT, USA. We investigated how commingling affected survival of radio-collared female bighorns that were released initially (founder) a...

Studies in wildlife ecology often involve species that are hunted, trapped, or are of additional economic or aesthetic importance to humans, including species that are rare, threatened, or endangered. The focus of the discipline is on the population rather than the individual; consequently, population ecology is central to wildlife conservation and...

Temporal changes in net energy balance of animals strongly influence fitness; consequently, natural selection should favor behaviors that increase net energy balance by buffering individuals against negative effects of environmental variation. The relative importance of behavioral responses to climate-induced variation in costs vs. supplies of ener...

Understanding population dynamics of ungulates is not conceptually simple, in part, because there are many counterintuitive processes. We attempt to disentangle important concepts, including density dependence, density independence, limitation, regulation, compensatory and additive mortality, and top-down versus bottom-up forcing by examining how t...

Vital rates of large herbivores normally respond to increased resource limitation by following a progressive sequence of effects on life-history characteristics from survival of young, age at first reproduction, reproduction of adults, to adult survival. Expected changes in life history characteristics, however, should operate through changes in nu...

Concentration of fecal nitrogen has been used widely as an indicator of dietary quality for free-ranging ruminants. Differences in digestive function between species of dimorphic ungulates render interspecific comparisons of fecal nitrogen unreliable; however, whether intraspecific sexual differences in digestive function also bias this nutritional...

The disruption of traditional migratory routes by anthropogenic disturbances has shifted patterns of resource selection by many species, and in some instances has caused populations to decline. Moreover, in recent decades populations of mule deer (Odocoileus hemionus) have declined throughout much of their historic range in the western United State...

Natural infections of giant liver flukes (Fascioloides magna) occur primarily in cervids and bovids. In northeastern North America, a common definitive host for giant liver flukes is the white-tailed deer (Odocoileus virginianus). Giant liver flukes cannot reproduce in moose (Alces alces) and eventually die, but only after causing extensive tissue...

We developed an original modeling approach using program Stella® to investigate the usefulness of predator–prey ratios (PPRs) for interpreting top-down and bottom-up forcing on moose Alces alces. We included density-dependent feedbacks for the moose population, allowed K to vary based on amount and quality of available forage for moose, integrated...

Average mean monthly temperatures at Grand

Examples of wetland habitat (dark gray) in comparison with open water (black) and other habitats (light gray) on townships, each 9.6 km on a side, illustrating the decrease in wetland habitat moving from the northwest (left panel) to the northeast (right panel) across our study areas in northeastern Minnesota, USA.

Our objective was to examine effects of groups of mixed numbers and ages of male North American elk Cervus elaphus on the reproductive performance of females. We conducted research at the Starkey Experimental Forest and Range in northeastern Oregon, USA, during 1993-2000. Each spring in late March, we released 40 female elk, eight yearling (9-month...

Background: Migration is an adaptive strategy that enables animals to enhance resource availability and reduce risk of predation at a broad geographic scale. Ungulate migrations generally occur along traditional routes, many of which have been disrupted by anthropogenic disturbances. Spring migration in ungulates is of particular importance for co...

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Body reserves of numerous taxa follow seasonal rhythms that are a function of temporal patterns in food availability and life‐history events; however, tests of the theory underlying the allocation of somatic reserves for long‐lived organisms are rare, especially for free‐ranging mammals. We evaluated the hypothesis that allocation of somatic reserv...

Hunting remains the cornerstone of the North American model of wildlife conservation and management. Nevertheless, research has indicated the potential for hunting to adversely influence size of horn-like structures of some ungulates. In polygynous ungulates, mating success of males is strongly correlated with body size and size of horn-like struct...

Studies in wildlife ecology often involve species that are hunted, trapped, or are of additional economic or aesthetic importance to humans, including species that are rare, threatened, or endangered. The focus of the discipline is on the population rather than the individual; consequently, population ecology is central to wildlife conservation and...

The disruption of traditional migratory routes by anthropogenic disturbances has shifted patterns of resource selection by many species, and in some instances has caused populations to decline. Moreover, in recent decades populations of mule deer (Odocoileus hemionus) have declined throughout much of their historic range in the western United State...

Context Timing (mean birthdate) and synchrony (variance around that date) of births can influence survival of young and growth in ungulate populations. Some restored populations of ungulates may not adjust these life-history characteristics to environments of release sites until several years after release, which may influence success of reintroduc...

We studied mountain lions (Puma concolor) and mule deer (Odocoileus hemionus) inhabiting a Great Basin ecosystem in Round Valley, California, to make inferences concerning predator—prey dynamics. Our purpose was to evaluate the relative role of top-down and bottom-up forcing on mule deer in this multiple-predator, multiple-prey system. We identifie...

Populations of mule deer Odocoileus hemionus have declined throughout most of their historic range in recent decades, and habitat alteration has been hypothesized as one potential cause of those declines. Consequently, understanding how patterns of behaviour change as landscapes are altered through time may provide important insights into mechanism...

Problem statement: Muskoxen (Ovibus moschatus) are distant relatives of sheep (Caprinae) and have roamed the Arctic for a million years, with populations reaching North America between 150,000 and 250,000 years ago. Muskox populations could be negatively influenced by climate change and increased exposure to contaminants. Since the snow depth is a...

We examined interactions related to resource partitioning and competition with density-dependent processes among mule deer Odocoileus hemionus and North American elk Cervus elaphus at two different population densities of elk. We used an experimental approach to examine changes in diet diversity, selection of diets, dietary importance, niche breadt...

Water availability and conservation are critically important components for the management of large, arid-land herbivores, especially in a changing climate. There have been a number of advances related to this topic; for example, multiple techniques have been developed to increase accessibility of natural and artificial water sources for bighorn sh...

Evidence of female fomentation of male–male aggression as a mechanism of mate choice is rare, especially in mammals. Female choice of mates in polygynous species may be masked by intense male competition or by males attempting to restrict female choice. We studied protest moans of female Alaskan moose Alces alces gigas in interior Alaska, USA, from...

In social ungulates particular individuals or cohorts, such as adult females, can lead or initiate foraging movements. We use muskoxen (Ovibos moschatus) as a model system to test hypotheses regarding the sex and age class of leaders and the potential costs of leadership in 3 different behavioral contexts: activity initiation, foraging-bout movemen...

We investigated diet of cougars (Puma concolor) in the eastern Sierra Nevada, California, following a decline in the population of mule deer (Odocoileus hemionus). Mule deer declined 84% from 1985 to 1991, a period concurrent with declines in bighorn sheep (Ovis canadensis sierrae; an endangered taxon). An index to numbers of cougars lagged behind...

We examined the roles of sex and spatial scale in habitat selection by Alaskan moose Alces alces gigas. We GPS-collared 11 female and seven male adult moose in the Tongass National Forest, Alaska, USA, during 2002-2004. We predicted that adult male and female moose would be spatially separated outside of the mating season, consistent with hypothese...

Phenological events of plants and animals are sensitive to climatic processes. Migration is a life-history event exhibited by most large herbivores living in seasonal environments, and is thought to occur in response to dynamics of forage and weather. Decisions regarding when to migrate, however, may be affected by differences in life-history chara...

Timing (mean birth date) and synchrony (variance around that date) of births can influence survival of young and population growth in ungulates. We quantified timing and synchrony of births in 2 populations of bighorn sheep (Ovis canadensis) that were acquired from different source herds and reintroduced to adjacent areas. From 2001 to 2007 we reco...

We studied the effects of the Exxon Valdez oil spill on the diets of river otters (Lutra canadensis) from oiled and nonoiled areas of Prince William Sound, Alaska, U.S.A., in 1989 and 1990. On the basis of identification of prey remains in their feces, otters fed principally on marine, bottom-dwelling fishes. Marine gastropods, bivalves, and crusta...

Knowledge of spatial needs of white-tailed deer is fundamental to effective management of their populations and habitats (Fulbright and Ortega-S, 2006). White-tailed deer, and other large mammals, require temporally and spatially diverse elements of habitat such as food, water, and cover, and these mammals can have signicant effects on vegetation c...

Fecal nitrogen (FN) has been applied widely as an index of dietary quality in studies of nutritional ecology of free-ranging and captive vertebrate herbivores, particularly ruminants. Three related articles in the Journal of Wildlife Management (JWM; Leslie and Starkey 1985, 1987; Hobbs 1987) have been cited (n = 150) in 87 publications and 39 peer...

We studied sexual segregation, particularly patterns of group membership for white-tailed deer (Odocoileus virginianus), in Lincoln County, Minnesota, USA, to evaluate current techniques used to categorize animals when studying sexual segregation. We categorized group membership according to Hirth (1977) and grouped individuals using our solitary c...

Males and females of most dimorphic ruminants segregate outside the mating season, which may necessitate that conservation efforts focus on differential resources used by the sexes. Dimorphic bighorn sheep Ovis canadensis are one of the rarest ungulates in North America with some populations listed as endangered. Water sources are important for the...

We studied sexual segregation in an endangered alpine ungulate, Sierra Nevada bighorn sheep (Ovis canadensis sierrae) in the Sierra Nevada, California, U.S.A., during winter 20052006. We tested hypotheses for sexual segregation to better understand that phenomenon and to obtain information critical for the conservation of these rare mammals. Female...

We introduce a new index for measuring perpendicularity of animal movements with respect to a boundary (e.g., a habitat patch edge), and provide a computer algorithm for its calculation. Our index, η, improves on an approach that measures perpendicularity with respect to a fixed boundary direction. This is because η accounts for moment-to-moment tr...

Little is known regarding the potential adjustment of maternal care towards late-born young by reintroduced female ungulates, which may be adapted to environments quite different than those at their release site. We compared nursing behaviors of young to investigate whether females would adjust maternal care toward late-born young between two popul...

We examined spatial distributions and resource partitioning among female mule deer (Odocoileus hemionus) and female North American elk (Cervus elaphus) during summer and winter in southeastern Idaho, USA. Our objective was to understand differences in distributions and habitat selection by these two species of large herbivores in a sagebrush-steppe...

Water sources are an important habitat component for populations of bighorn sheep (Ovis canadensis), and the technique of sampling at water sources has been used extensively to study behaviors and estimate parameters of bighorn populations, Little is known, however, concerning the time of day at which groups of bighorns visit water. Understanding w...

The relationship between hunters and their environment is a key component in managing wildlife populations. Identifying hunter's characteristics, motivations, and efforts is crucial to understanding if a hunt will be successful. We predicted that landscape characteristics and moose (Alces alces) densities would affect success of hunts. As in wildli...

Recent declines of mule deer Odocoileus hemionus, ostensibly a result of low rates of recruitment, highlight the importance of understanding relationships between parturient females and their critical habitats. We estimated timing of parturition for 20 mule deer in northeastern Oregon, USA, using movement data from global positioning system (GPS) c...

We studied black-tailed deer, Odocoileus hemionus columbianus, in northern California, USA, during winter to test the importance of thermal conditions on habitat selection. During warm days, temperatures from black-body devices were higher than ambient air temperatures in habi-tats other than live oak, Quercus wislizenii, but were closer to ambient...