Roads pose two central problems for wildlife: wildlife-vehicle collisions (WVCs) and habitat fragmentation. Wildlife exclusion fencing can reduce WVCs but can exacerbate fragmentation. In Chapter 1, I summarize the relevant studies addressing these two problems, with a focus on large mammals in North America. Chapters 2 and 3 summarize field assessments of technologies to reduce WVCs and maintain connectivity, specifically jumpout ramps and underpasses, along Highway 101 near San Luis Obispo, CA. In a fenced highway, some animals inevitably breach the fence and become trapped, which increases the risk of a wildlife-vehicle collision. Earthen escape ramps, or “jumpouts”, can allow the trapped animal to escape the highway corridor. Few studies have quantified wildlife use of jumpouts, and none for >2 years. We used wildlife cameras to quantify wildlife use of 4 jumpouts from 2012-2017. Mule deer were 88% percent of our detections and jumped out 20% of the time. After accounting for pseudoreplication, 33% of the events were independent events, and 2 groups of deer accounted for 41% of all detections at the top of the jumpout. Female deer were 86% of the detections and were much more likely than males to return to the jumpout multiple times. This is the first study to document use of jumpouts for more than 3 years, the first to account for pseudoreplication, and the first to quantify differences in jumpout use between male and female mule deer. We recommend a jumpout height between 1.75m-2m for mule deer to increase the jumpout success rate. Chapter 3 addresses factors that may affect the use of undercrossings by mule deer and other wildlife. Wildlife crossings combined with wildlife exclusion fencing have been shown to be the most effective method to reduce wildlife-vehicle collisions while maintaining ecological connectivity. Although several studies have quantified wildlife use of undercrossings, very few have exceeded 24 months, and the factors affecting carnivores use of the undercrossings remain unclear. We quantified mule deer, black bear, mountain lion, and bobcat use of 11 undercrossings along Highway 101 near San Luis Obispo, California from 2012-2017. We constructed zero-inflated Poisson general linear models on the monthly activity of our focal species using underpass dimensionality, distance to cover, substrate, human activity, and location relative to the wildlife exclusion fence as predictor variables. We accounted for temporal variation, as well as spatial variation by quantifying the landscape resistance near each undercrossing. We found that deer almost exclusively used the larger underpasses whereas the carnivores were considerably less selective. Bears used undercrossings more that were within the wildlife exclusion fence, whereas mountain lion activity was higher outside the wildlife exclusion fence. Bobcat activity was highest and most widespread, and was negatively associated with distance to cover. Regional connectivity is most important for bear and mountain lion, and the surrounding habitat may be the most important predictor for their use of undercrossings. We recommend placing GPS collars on our focal species to more clearly document fine-scale habitat selection near the highway.

Mule deer are an important rangeland grazer, large prey species, and game animal for the state of Utah, so herd size is monitored and managed actively. A significant cause of population decline is poor overwintering survival, including from the lack of available forage during winter months. Mule deer energy storage is correlated with greater overwintering success, so physical estimates of energy storage including body condition score (BCS), rump fat (RF), and loin thickness (LT), can be used to track and predict a herd's health. Current methods of collecting deer information are costly, time consuming, and cause physical stress to deer, so here we sought to test if a microbiome analysis could be used to predict deer overwintering success. We analyzed nearly 1000 fecal samples collected from deer in Utah over a five-year period. We found that the microbiome composition of these samples shared characteristics with published reports of other reported ruminant species. Also, the location and time when the samples were collected significantly influenced mule deer microbiota composition and abundance. We found that there is a relationship between microbes and health measures (BCS, RF, LT), including some microbial abundances that could predict the health measures of mule deer several months ahead of time. There were also microbial groups whose abundances were significantly correlated with the latitude and elevation of the deer. Finally, a longitudinal analysis on a subset of sampled deer produced slightly different results than the broad analysis of all samples, including suggesting that some of the differences in microbiota composition with time may have been related more to sampling distinct deer at different time points, rather than that the deer microbiota composition changed with time. . These results suggest possible candidate microbial taxa for use in developing assays to replace current methods of measuring and tracking deer health.

No description available.

Mule deer (Odocoileus hemionus) from the US Air Force Academy (USAF A) at Colorado Springs, Colorado have shown antler fractures and tooth lesions. Brittle bones and tooth lesions have been associated with high ingestion of fluorides. The present study compared prevalence and severity of tooth lesions with fluoride content in teeth, bones and antlers of mule deer from USAF A with deer from other two areas in Colorado. Mule deer tissues were collected during 1993-1995 from: USAF A (N=262), Pinon Canyon Maneuver Site (pCMS, N=24), and game management units (GMU's) in northwestern Colorado (N=16). The severity of tooth lesions was rated using a 0 (normal) to 5 (severe hypoplasia) scale. In all areas the median lesion score was 1; the highest score in USAFA was 5 vs. 3 in the other areas. Median fluodide concentrations (Jlg/g d.w.) were higher (p<0.002) in second incisors and bones of mule deer collected at the USAFA (669.9, N=246 incisors, 744.5, N=247 bones) than in deer from PCMS (507.3; 494.7, N=24) and GMU's (426.2,466.2, N=16), respectively. Within the USAF A, median fluoride concentrations in teeth and bones were lower (P<O. 001) in fawns and yearlings than in older animals and in males (> I. 5 years) than in females. Median fluoride concentrations were lower (P<O. 001) in deciduous than in permanent teeth. Median concentrations of fluoride were higher (P<O.OO1) in non-erupted teeth than in deciduous teeth and bone indicating a high rate of accumulating fluoride in growing hard tissue. Fluoride concentration was higher (P<O. 00 1) in teeth with lesions than without lesions. / Master of Science

Mule deer (<i>Odocoileus hemionus</i>) population dynamics, movements, and habitat use were studied on the Pinon Canyon Maneuver Site in southeastern Colorado during January 1983-December 1984. Thirty-eight adults and 28 fawns were radio collared, and 35 adults were color collared or ear tagged. Population estimates were 365 and 370 deer for 1983 and 1984, respectively. The sex ratio (yearling and adult) was 60 males: 100 females. Adult female pregnancy rate was 95%; the mean litter size for females over 1.5 years was 1.7 fawns. Annual fawn survival was 29% in 1983 and 22% in 1984. Coyote (<i>Canis Iatram</i>) predation was responsible for 76% of fawn mortality. Adult survival was 88% in 1983 and 87% in 1984; coyote predation accounted for 67%, and hunting for 33% of the annual adult mortality. The calculated annual rate of increase (λ) was 1.01, indicating a stable population. Seasonal home range size differed (p < 0.05) between males and females only in the fall. Females preferred pinyon-juniper woodland in all seasons, and shrub grassland in winter, summer and fall; proportional use of woodland/open grassland and shrub/open grassland edge was greater than proportional availability. Males preferred pinyon-juniper woodland and avoided open grassland in all seasons. Fawns preferred shrub grassland and shrub/open grassland edge; they avoided cholla/open grassland edge. Fawns selected bed sites with greater (P < 0.05) concealment cover at all 0.5 m intervals up to 2 m in height, and greater ground cover of trees, shrubs, and grasses (P < 0.01) than random sites. / Master of Science

During January 1986 - September 1988 I studied the behavioral and demographic responses of mule deer (Odocoileus hemionus) to military activity on the Pinon Canyon Maneuver Site in southeastern Colorado. Military training was initiated on the site during August 1985 and recurred approximately 3 times yearly for periods of a month. During a maneuver, 3/7 of the site was used for training in accordance with a rotational land use schedule. I radio-collared fifty adult deer and 49 fawns. Female seasonal home ranges were larger in maneuver than non maneuver areas. During the nonsummer period female home ranges were larger in previous-maneuver than non maneuver areas. Fawn summer home ranges were larger in maneuver than previous-maneuver areas. Male home range sizes differed only for 50% harmonic mean transformation annual home ranges; bucks in maneuver areas had larger home ranges than in non maneuver areas. Female deer in maneuver areas exhibited significant home area shifts between pre maneuver and maneuver periods more frequently (40%) than did deer in non maneuver (control) areas (12.5%). Mule deer in military training areas may have responded to human harassment, alteration of security cover, or destruction of the forage base. I suggest that deer may exhibit a more negative response to unpredictable than predictable disturbances. Demographic data were compared to previous baseline data (1983-1984). Buck annual survival rates did not differ during 1983-1988; doe annual survival rates also were similar during this period. Summer fawn survival differed only between 1984 and 1987, being higher in 1987. All fawn mortalities either were caused or scavenged by coyotes (Canis latrans). Pregnancy rates and fawn production ranged from 88-96% and 1.4-1.7 fawns/doe, respectively. Also, fawn:doe ratios were similar during 1983-1988. Although population estimates increased between 1984 and early 1988, the population declined during late 1888. Two important confounding factors existed on the site during 1983-1988 which make it difficult to assess the effect of military activity on mule deer demographics. First, extensive cattle grazing occurred prior to acquisition of the site and continued through most of the baseline study. Secondly, coyote control was conducted during 1987-1988. These factors may have allowed the deer population to perform better under disturbance conditions. Aerial quadrat sampling was preferred over line transect sampling for censusing mule deer in low density pinyon-juniper (Pinus edulis-Juniperus monosperma) habitat. Management recommendations included training restrictions during fawning season and in severe winters, as well as revegetating disturbed areas. / Master of Science

O Brasil é um dos países com o maior número de transferências de embriões de equinos do mundo, mas as éguas receptoras são escassas e caras. Uma alternativa é usar mulas acíclicas como receptoras de embriões equinos. O objetivo deste estudo foi comparar pela primeira vez o desenvolvimento embrionário e fetal precoce em mulas e éguas receptoras do 10º ao 60º dia de gestação. Este estudo foi realizado na Fazenda Experimental Gralha Azul da Pontifícia Universidade Católica do Paraná. Cinco éguas de doadores de embriões com idades entre 4 e 10 anos foram utilizadas. Foram utilizados dois grupos de receptores: 10 éguas cíclicas com idades entre 4 e 15 anos (grupo controle) e 7 mulas acíclicas com idades entre 6 e 12 anos. Os animais foram mantidos em piquetes e/ou estábulos e tiveram acesso a água e sal mineral ad libitum, bem como a uma fonte de volumoso e concentrado. As éguas doadoras foram monitoradas diariamente por ultrassonografia transretal (transdutor linear de 5 MHz, A6V Sonoscape, China) após o início do estro. As éguas foram inseminadas artificialmente usando sêmen fresco de um garanhão com fertilidade comprovada. A coleta de embriões das éguas foi realizada 8 dias após a ovulação. Antes da transferência do embrião, as éguas receptoras cíclicas eram examinadas diariamente por ultrassonografia para usar a melhor sincronia com a ovulação da doadora. As mulas acíclicas foram preparadas antes da transferência do embrião com a administração de 17 beta-estradiol (10 mg/mL, 1 mL, im) no dia da ovulação da doadora, e após 2 dias quando a presença de edema uterino foi confirmada, com a administração de Altrenogest (60 mg/mL, 5 mL, im). O diagnóstico de gestação foi realizado por ultrassonografia, 10 dias após a ovulação da doadora. Quando o diagnóstico foi confirmado, a avaliação ultrassonográfica foi realizada diariamente até o 60º dia de gestação. O primeiro dia de detecção da vesícula embrionária foi o Dia 10 por ultrassonografia em ambas as espécies e Dia 20,9 ± 1,3 (Média ± DP) e 21,9 ± 0,9 por palpação transretal em mulas e éguas respectivamente. A fixação da vesícula ocorreu em média no dia 15,7 ± 1,1 em mulas e 16,6 ± 1,7 em éguas. O embrião propriamente dito foi detectado pela primeira vez em mulas (no dia 19,9 ± 1,1) em comparação com as éguas (20,4 ± 1,3). O batimento cardíaco foi observado posteriormente em muares (23,4 ± 1,4) do que em éguas (22,6 ± 0,8). O saco alantóide foi detectado pela primeira vez entre os dias 23 e 26 (25,3 ± 1,1 e 24,6 ± 1,0 em mulas e éguas, respectivamente) e o cordão umbilical foi detectado pela primeira vez no dia 39 (39,7 ± 2,1 x 39,6 ± 1,5 em mulas e éguas, respectivamente). Os diâmetros ovarianos para os ovários esquerdo e direito foram semelhantes para as mulas (21,4 ± 0,4 vs. 21,8 ± 0,4 mm) e para as éguas (45,1 ± 0,4 vs 46,0 ± 0,4). Entretanto, o diâmetro ovariano das éguas (45,5 ± 0,3 mm) foi duas vezes maior (P <0,0001) que as mulas (21,6 ± 0,3 mm). Apenas duas mulas apresentaram o CL acessório que foi observado pela primeira vez nos dias 49 e 51. Dentro dos grupos não houve diferenças entre os cornos esquerdo e direito, gravídicos e não-gravídicos. A média geral não foi diferente entre as mulas (24,6 ± 3,1 mm) e as éguas (25,4 ± 0,1 mm). Como conclusão, de acordo com o nosso conhecimento, este é o primeiro estudo comparativo sobre desenvolvimento embrionário e fetal precoce entre mulas acíclicas e éguas receptoras de embriões equinos. Numerosas semelhanças foram encontradas nos aspectos estudados. Tais achados, associados ao fato de que potros vivos e sadios foram produzidos, sugerem que o uso de mulas acíclicas pode ser considerado como uma alternativa para aumentar a disponibilidade de receptoras em programas equinos de TE. / Brazil is one of the countries with the largest number of equine embryo transfers in the world, but recipients mares are scarce and expensive. One alternative is to use acyclic mules as recipients for equine embryos. The aim of this study was to compare for the first time the embryonic and early fetal development in recipient mules and mares from day 10 to 60 of pregnancy. This study was conducted at the Experimental Farm Gralha Azul of the Pontifical Catholic University of Paraná. Five embryo donor mares aged 4 to 10 years were used. Two groups of recipients were used: 10 cyclic mares aged 4 to 15 years (control group), and 7 acyclic mules aged 6 to 12 years. Animals were kept in paddocks and/or stables and had access to water and mineral salt ad libitum, as well as to a source of roughage and concentrate. Donor mares were monitored daily by transrectal ultrasonography (5-MHz linear transducer, A6V Sonoscape, China) after the beginning of estrus. The mares were artificially inseminated using fresh semen from a stallion with proven fertility. Embryo collection from the mares was performed 8 days after ovulation. Before embryo transfer, cyclic recipient mares were examined daily by ultrasonography to use the most synchronous with the donor's ovulation and have not received any hormonal treatment. The acyclic mules were prepared before the embryo transfer with the administration of 17 beta-estradiol (10 mg/mL, 1 mL, i.m.) on the day of the donor's ovulation, and after 2 days when the presence of uterine edema was confirmed, with the administration of Altrenogest (60 mg/mL, 5 mL, i.m.). The pregnancy diagnosis was carried out by ultrasonography 10 days after ovulation in the donor. When the diagnosis was confirmed, ultrasonographic assessment was carried out daily until day 60 of pregnancy. The first day of detection of an embryonic vesicle was Day 10 by ultrasound in both species and day 20.9 ± 1.3 (Mean ±SD), and 21.9 ± 0.9 by transrectal palpation in mules and mares respectively. Fixation of the vesicle occurred on mean day 15.7 ± 1.1 in mules and 16.6 ± 1.7 in mares. The embryo proper was first detected in mules (on day 19.9 ± 1.1) compared to mares (20.4 ± 1.3) The heart beat was observed later in mules (23.4 ± 1.4) than in mares (22.6 ± 0.8). The allantoic sac was first detected between days 23 and 26 (25.3 ± 1.1 and 24.6 ± 1.0 in mules and mares, respectively) and the umbilical cord was first detected on day 39 (39.7 ± 2.1 x 39.6 ± 1.5 in mules and mares, respectively). The ovarian diameters for left and right ovaries were similar for mules (21.4 ± 0.4 vs. 21.8 ± 0.4 mm) and for mares (45.1 ± 0.4 vs. 46.0 ± 0.4). However, the ovarian diameter of the mares (45.5 ± 0.3 mm) was two times larger (P<0.0001) than the mules (21.6 ± 0.3 mm). Within groups there were no differences between left and right and gravid and non-gravid horns. Data were combined for comparison of the endometrial diameter between mules and mares. The overall mean was not different between mules (24.6 3.1 ± 0.1 mm) and mares (25.4 ± 0.1 mm). However, day (P<0.003) and group-by-day (P<0.0001) effects were detected. Only two mules presented accessory CL that was observed for the first time on days 49 e 51. In conclusion, to the best of our knowledge, this is the first comparative study on embryo and early fetal development between noncycling mules and mares used as ET recipients of horse-horse embryos. Numerous similarities in embryo and early fetal development, and endocrinology aspects were seen. The findings of this study in mules, associated with the fact that alive and healthy offspring were produced, the use of mules may be considered as an alternative to increase the availability of recipients in equine ET programs.

Le microbiote intestinal constitue un élément important pour l’hôte, il est impliqué notamment au niveau immunologique ou physiologique. La connaissance de la composition de ce microbiote est la première étape dans la compréhension des phénomènes qui lui sont associés. Les travaux de cette thèse se sont articulés selon plusieurs objectifs. La première étape a été de faire un état des lieux de la composition du microbiote de deux types génétiques parentaux : le canard Pékin (Anas Platyrhynchos), le canard de Barbarie (Cairina Moschata) ainsi que de leur hybride ; le canard mulard. Nous avons ainsi pu observer des compositions différentes selon le type génétique avec tout de même la prédominance dans chacune des trois espèces de deux phyla : les Firmicutes et les Bacteroidetes. Différentes conditions rencontrées dans l’environnement sont à même de créer un déséquilibre dans la composition du microbiote. Une des conditions possibles est un changement dans l’alimentation ainsi la seconde étape a été de voir l’impact du gavage sur les communautés bactériennes composant le microbiote. Celui-ci induit bien des modifications au sein du microbiote en privilégiant certaines classes bactériennes notamment les Bacilli et les Clostridia selon le type génétique. Un effet du gavage a été montré au niveau du microbiote iléal tandis que l’on retrouve un effet du type génétique ainsi que du gavage mais plus faible que dans l’iléon au niveau des caeca. Deux autres travaux ont été réalisés, le premier concernait l’ajout d’un probiotique (Lactobacillus sakei) sur le microbiote des canards mulards durant la phase de gavage. Nous avons montré que lors de cet ajout, nous observions une forte augmentation des lactobacilli au niveau de l’iléon. Enfin suite aux fortes contaminations retrouvées dans le sud-ouest ainsi que ses effets toxiques montrés dans différentes études, le dernier travail effectué a été de voir l’effet du cadmium sur le microbiote des canards Pékin et Barbarie. Nous avons pu ainsi observer les modifications de la communauté microbienne lors de l’ajout de cadmium ainsi l’accumulation de celui-ci dans les reins au cours du gavage. Des effets combinés entre le cadmium et la période de gavage ainsi qu’avec le type génétique ont été mis en lumière. Une tendance à une accumulation différentielle du cadmium a été observé selon le type génétique. / The intestinal microbiota is an important element for the host; it is particularly involved in immunological or physiological level. Knowledge of the composition of the microbiota is the first step in understanding the phenomena associated with it. The work of this PhD was organized according to several objectives. The first step was to realize a molecular inventory of the microbiota composition of the two parental genetic types: the Pekin duck (Anas Platyrhynchos), the Muscovy duck (Cairina moschata) and their hybrid, the mule duck. We have observed different compositions depending on the genetic type although with a predominance of two phyla: the Firmicutes and Bacteroidetes for all ducks species. Different conditions encountered in the environment are likely to create an imbalance in the composition of the microbiota. One is a change in diet; therefore the second step was to see the impact of overfeeding on bacterial communities. Overfeeding causes many changes in the bacterial microbiota and increase two classes: Bacilli and Clostridia according to the genetic type. The effect of overfeeding has been shown principally on the ileal microbiota while genetics and overfeeding both affected weekly cecal microbiota. We then studied the impact of adding a probiotic strain (Lactobacillus sakei) on the microbiota of mule ducks during the overfeeding period. We could see here a significant effect of this addition only in the ileum with a sharp increase in lactobacilli. Finally, due to high levels of contamination found in the southwest of France and its toxic effects on metabolism shown in various studies, the last work was to see the effect of cadmium on the microbiota of Pekin and Muscovy ducks. We observed changes in the microbial community when adding cadmium and see the accumulation of it in the kidneys during overfeeding. Combined effects between cadmium and the feeding period as well as the genetic type were highlighted. Finally

L’objectif de ce projet était de comprendre comment l’expression du génome influence les caractères de qualité du foie gras, tels que le poids de foie, le taux de fonte et les teneurs, en lipides et protéines, et d’identifier les mécanismes moléculaires sous-jacents. Afin de répondre à ces objectifs, nous avons dans un premier temps étudié l’expression différentielle de protéines selon les phénotypes des foies des canards mulards puis dans un second temps, nous avons entrepris d’identifier des QTL phénotypiques et protéiques (pQTL) à l’aide d’une nouvelle carte génétique composée de marqueurs SNP et microsatellites. Tout d’abord, une optimisation du dispositif expérimental a été entreprise : 3 famille F1, composées de 98 canes backcross et de leurs 294 fils mulards ont été sélectionnés pour leur contribution à des QTL existants liés à la qualité du foie gras. La première approche nous a permis de montrer que les foies ont des profils protéiques et métaboliques différents selon leur phénotype. Ainsi, les foies légers qui fondent peu, avec une faible teneur en lipides mais une forte teneur en protéines présentent un processus anabolique par la surexpression de protéines impliquées dans les métabolismes lipidiques, glucidiques, de synthèse. Au contraire, les foies lourds, fondant beaucoup, avec une forte teneur en lipides mais une faible teneur en protéines présentent des mécanismes de cytoprotection et de réponse au stress. La seconde approche nous a permis de mettre en évidence 30 QTL relatifs à des phénotypes de qualité du foie gras et 50 pQTL relatifs à différentes protéines. Sept chromosomes se démarquent par la ségrégation de plusieurs QTL et pQTL permettant d’émettre des hypothèses quant aux fonctions des gènes sous-jacents à ces QTL. Entre autres, le locus d’APL15 semble lié à la glycolyse et celui d’APL18 à des processus de survie cellulaire. L’ensemble de ces résultats permet ainsi non seulement d’identifier les voies métaboliques impliquées dans la qualité du foie, mais également d’établir un lien entre les caractères, les protéines et les loci des QTL suggérant un déterminisme génétique de ces voies métaboliques impliquées. Ces relations nécessitent d’être approfondies afin de préciser les processus et les gènes impliqués dans la qualité du foie gras. / The aim of this project was to understand how the genome expression influences liver quality traits such as liver weight, melting rate, lipid and protein rates, and to identify the molecular mechanisms underlying it. First, we studied the differential expression of proteins according to liver quality traits of mule ducks. Then we carried out detections of uni-trait and multi-traits phenotypic QTL and protein QTL using a new genetic map containing SNP and microsatellite markers. In preamble to the study, the optimization of the experimental disposal was necessary: 98 backcross dams and their 294 mule sons, composing 3 F1 families were selected because of their contribution to the likelihood of existing QTL related to foie gras quality. The first study showed that livers presented different protein and metabolic profiles according to their phenotypes. Indeed, light livers, with low melting rate, low lipid rate and high protein rate show an over-expression of proteins involved in lipid, glucid or in synthesis metabolism, suggesting an anabolism process. On the contrary, heavy livers, with high melting rate, high lipid rate and low protein rate show cytoprotection and response to stress mechanisms. The second study highlighted 30 QTL related to liver quality traits and 50 pQTL related to different proteins. In particular, 7 chromosomes segregated several QTL and pQTL, permitting to assess hypothesis on the functions of the genes underlying these QTL regions. As an example, the APL15 locus seems linked to glycolysis and the APL18 one seems linked to cell survival ones. All these results helped in identifying metabolic pathways implicated in liver quality as well as establishing a link between traits, proteins and the QTL loci, suggesting a genetic determinism of these pathways. These relationships need to be further studied in order to bring precision to the process and to determine more precisely the genes implicated in the foie gras quality traits.

This study examined the feeding responses of mule deer to a system of spring livestock grazing. The specific purposes were 1) to determine botanical composition of diets selected by mule deer on a winter range subjected to previous spring grazing by sheep compared to one with no sheep grazing and 2) to develop a basis for predicting selection of individual plants by deer, based on physical characteristics of the plants and the species and physical proximity of associated plants. The study was conducted within the framework of a completely randomized experimental design with two treatments. Variables controlled for each unit of observation were grazing treatment (prior sheep grazing and no sheep grazing), sampling periods within the winter (early winter and late winter), weeks (four within each period), days (four within each week), sampling times (four each day), age of animal (fawns and adults) and identity of observer. Two adjacent 2.4 ha pastures were fenced. A sheep grazing treatment of 150 sheep days per ha was applied in late May, 1974, to one pasture. Five hand-reared mule deer were placed in each pasture for two six-week periods, one in early winter and the other in late winter. Diets were quantified by a mouthful count technique and hand plucking representative mouthfuls of each species consumed. Plant physical characteristics were measured while following grazing deer. For each plant encountered by the deer, the following variables were measured: species name, distance from the deer, height and width, degree of prior utilization, proportion of current live plant material present, species of and distance to nearest neighboring plant, and consumption or non-consumption of the plant by the deer. Differences were found between treatments in forage availability and abundance, and in botanical composition of diets selected by mule deer. The dietary differences were attributed to a greater proportion of current year's bitterbrush forage being available in the sheep grazed treatment and to reduced interference there from standing dead grass in selection of preferred green grasses and forbs. Deer diets in the sheep grazed pasture were higher in herbaceous plant material than in the deer pasture. Seasonal dietary changes were due to reduced plant availability by deer grazing, snow cover, and plant phenology. Major changes were an increase in shrub consumption through the early winter and well into the late winter periods, and a simultaneous decline in herbaceous species consumption. Snow melt and spring green-up permitted a sudden shift to forbs and grasses near the end of the late winter period. Plant attributes capable of predicting consumption of individual plants included 1) degree of prior utilization, 2) amount of current live plant material present, 3) distance of plant from grazing animal, 3) species of nearest plant, and 4) plant height. These characteristics probably exerted their influence indirectly through olfactory and tactile stimuli to the deer. The use of these attributes to place plants in consumed and not-consumed groups indicated that grazing deer probably cue on fairly specific plant characters in selecting plants for consumption.