Bands of domestic sheep lambing on the open range in south central Wyoming were monitored for predator losses prior to and following coyote (Canis ·1atrans) removals. Experimental treatments, including 1) no removal (control), 2) removal of 2 adults and their pups, and 3) removal of pups only, were replicated 15 times each. Number of predation incidents (events) was reduced 98.2% by removing adults and pups. The number of sheep killed was reduced by 98.8%. Removing only litters of pups resulted in a decrease of 87.7% total kills decreased 91.6%. in predation incidents, while Overall, 23 of 30 predation sequences terminated immediately, while in all cases predation ceased within 3 days after removing adult coyotes and/or their pups. In terms of "offending individuals", denning can be a very selective means of coyote depredation control. The data suggest that removing only litters of offending adults can be nearly as effective in stopping losses as removing the adults. Biological parameters such as litter size did not appear to influence kill frequencies. A cost-effectiveness analysis was calculated.

Much of the decline of the U.S. sheep industry has been attributed to losses caused by predators. Most predatory losses are inflicted on lambs rather than ewes. Losses have historically ranged from 4-8% of lamb crops, inflicting significant financial loss on ranchers. However, most research providing data on sheep predation is over 20 years old. Changes in the sheep industry as well as predation rates may make previous loss rates inapplicable to current conditions. Coyotes (Canis latrans) are the primary predator of concern when it comes to sheep losses, but increasingly, cougars (Felis concolor) and black bears (Ursus americanus) are reported to be responsible for an increased proportion of lamb losses. I replicated a sheep depredation study conducted during the early 1970s in southwestern Utah and compared the results of the two studies to reassess losses and the predator species responsible for those losses. Total lamb losses to all causes in my study were comparable to losses reported in the 1970s as well as categories of verified and estimated predator losses. There was a significant variation in lamb losses between the 2 years of my study due to an increase in predator kills on sheep. Cougar and bear depredations occurred at significantly higher rates during my study than during the 1970s but did not produce an additive effect to overall predator losses. Most lambs killed by predators were located on or near pasture bed grounds as reported by other studies, but a large number were found >500 m from bed grounds. Rough terrain and scavenging by California condors (Gymnogyps californianus) made location of missing sheep difficult. The ability of cougars and bears to remove sheep carcasses from kill sites made the finding of sheep carcasses more difficult and caused an underreporting of sheep killed by these predators. I found that the loss of sheep to predation continues to be a problem for the sheep industry and its magnitude was unchanged from historic predation levels.

Les modifications de l'habitat (perte et fragmentation) sont considérées comme la principale cause de perte de biodiversité à l'échelle planétaire. Ces changements peuvent bouleverser l'équilibre des écosystèmes présents, contraignant certaines populations à ne subsister que dans les habitats résiduels où elles sont souvent isolées et limitées à une petite taille. Inversement, les modifications de l'habitat peuvent favoriser d'autres espèces qui se trouvaient jusque là limitées par les conditions existantes. Une problématique importante survient quand les espèces favorisées sont susceptibles d'avoir un impact négatif important sur une population déjà fragilisée par les modifications de l'habitat. Une situation de ce type existe pour le caribou de la Gaspésie, une population considérée « en voie de disparition » vivant principalement dans un parc de conservation, mais fréquentant également des secteurs où les modifications d'habitats sont importantes en raison de la coupe forestière. En outre, ces dernières sont susceptibles de favoriser les prédateurs de cette population de caribous, l'ours noir (Ursus americanus) et le coyote (Canis latrans). Deux sessions d'un programme de contrôle des prédateurs réalisés entre 1990 et 1996 puis de façon récurrente depuis 2001 avaient pour but de limiter les populations de ces prédateurs dans les secteurs utilisés par les caribous mais, afin d'assurer une protection à long terme, d'autres connaissances étaient nécessaires. Cette thèse de doctorat avait pour principal objectif d'accroître l'état des connaissances sur l'utilisation de l'espace par l'ours noir et le coyote et de détailler plus spécifiquement comment les caractéristiques d'un milieu boréal et montagnard influencent la sélection de l'habitat par l'ours noir. À l'aide de ces données nous désirions accroître l'information permettant d'identifier des mesures pour limiter les interactions de ces prédateurs avec les caribous de la Gaspésie. Un suivi télémétrique réalisé au cours de trois années (juillet 2002 -novembre 2005) sur 24 ours noirs et 16 coyotes équipés de colliers GPS a servi de base à ce projet. L'analyse des patrons d' utilisation de l'espace par ces deux espèces nous a permis de montrer que malgré une faible densité de leurs populations respectives, la taille et l'organisation spatiale de leurs domaines vitaux pouvaient leur permettre d'accéder en grand nombre aux zones utilisées par les caribous. Les mouvements des prédateurs s'étendaient à une échelle beaucoup plus grande que celle à laquelle avait eu lieu les deux sessions du programme de contrôle des prédateurs. Ces caractéristiques expliquaient probablement la durée limitée des effets positifs du contrôle sur le recrutement du caribou après l'arrêt du premier programme de contrôle. Les patrons d'utilisation de l'espace des prédateurs pouvaient expliquer également le maintien du nombre de prédateurs capturés annuellement lors de la deuxième période de contrôle, et ce, malgré une pression de piégeage importante. Afin d'assurer la protection des caribous à long terme, nos résultats suggèrent également l'importance d'aménager l'habitat autour du parc de la Gaspésie et d'y limiter les populations de proies alternatives comme les orignaux de façon à ne pas favoriser les prédateurs. Grâce aux données précises obtenues avec les colliers GPS nous avons modélisé la sélection de l'habitat par l'ours noir sous la forme d'une fonction de sélection des ressources (FSR). En incluant dans l'analyse plusieurs facteurs biotiques et abiotiques, nous avons mis en évidence diverses adaptations comportementales de l'ours noir à la forêt boréale. À l'aide d'une analyse du régime alimentaire et d'un suivi de la phénologie des plantes, nous avons détecté des modifications temporelles dans leur sélection de l'habitat en réponse aux changements de la disponibilité des ressources alimentaires. Ainsi, les ours faisaient des mouvements altitudinaux saisonniers. Au printemps, ils utilisaient principalement les espèces graminoïdes qu'ils trouvaient sur les sommets des montagnes. En été, par contre, ils se nourrissaient de fruits mous (e.g. framboises, fruits d'aralie et de cornouiller stolonifère) qu'ils recherchaient à basse altitude dans les milieux perturbés issus d'épidémies d'insectes et de certains types de coupes forestières. Enfin, en automne, les ours se déplaçaient vers les moyennes altitudes et utilisaient des secteurs faiblement ensoleillés, recherchant probablement des milieux dans lesquels la phénologie des plantes était retardée. Les fruits du sorbier (Sorbus americana) représentaient alors une très grande proportion de leur régime alimentaire. Des résultats de cette étude, nous proposons des aménagements de l'habitat, qui pourraient être mis en oeuvre pour limiter la présence de l'ours noir à proximité de la population de caribous de la Gaspésie. Ainsi, les coupes forestières de type CPRS devraient être évitées car elles aboutissent à la création de milieux riches en fruits qui sont particulièrement recherchés par les ours. Les coupes partielles devraient par contre être privilégiées car elles sont généralement peu utilisées, voir évitées. Comprendre comment les animaux réagissent à l'hétérogénéité de l'environnement est crucial si on veut comprendre l'impact des modifications de l'habitat. En nous basant sur la méthode des « temps de premier passage » (« First-passage time »), nous avons pu montrer que les ours ne parcouraient pas le milieu aléatoirement, mais qu'ils regroupaient leurs activités selon deux échelles spatiales. La taille des échelles spatiales utilisées par les ours variait au cours de l'année, vraisemblablement en réponse au changement de la disponibilité des ressources alimentaires. En considérant les échelles de sélection détectées chez chacun des individus, nous avons pu montrer que les variations dans les patrons de déplacements des ours noirs étaient associées à certaines variables comme la proportion de milieux perturbés ou dénudés, l'altitude et l'irradiation solaire, mais que l'effet de ces variables pouvaient changer au cours de l'année. Les patrons de distribution des espèces sont très importants à prendre en compte pour identifier les secteurs d'intérêt dans une problématique de conservation. Ainsi, une connaissance détaillée de l'écologie de l'espèce à protéger est essentielle pour réussir un programme de rétablissement. Toutefois, lorsque cette espèce est menacée par la prédation, nos résultats montre qu'il est également indispensable de considérer l'utilisation de l'espace et la sélection de l'habitat des prédateurs afin de définir les éléments du paysage et les échelles à considérer pour réaliser des aménagements d'habitats qui favoriseront une protection durable pour les espèces menacées. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Utilisation de l'espace, Sélection de l’habitat, Échelles de sélection, Conservation, Espèces menacées, Ours noir, Coyote, Caribou.

No description available.

Coyotes fed upon agricultural carrion at feedlots operated by the Farmer's Investment Company (FICO) and Roisland Farms. Agricultural carrion was not available in the Whetstone area. The FICO feedlot stopped operating in May 1976, and carrion was not available there after that time. Coyotes were trapped and shot at the FICO feedlot from November 1975 through March 1976, from June through August 1976, and from May through August 1977. Coyotes were trapped at Roisland Farms in July and August 1976 and January and February 1977. A trapper collected coyotes in the Whetstone area from January through March 1976 and from November 1976 through February 1977. I operated a scent station line on the Santa Rita Experimental Range on a monthly basis from October 1975 through June 1976, from September 1976 through June 1977, and in December 1977. From data on the visitation of scent stations by coyotes, lagomorphs, and small mammals I calculated indices of monthly relative abundance for each animal group. There were no differences among the age distributions, weights, ovulation rates, and litter sizes of coyotes from the 3 study areas. The mean weights of all adult-sized male and female coyotes collected during this study were 11.1 and 9.3 kg, respectively. The overall mean ovulation rate and mean litter size were 4.1 and 3.4, respectively. At FICO and Roisland, 70 to 90% of yearling and adult females bred, but only 20% bred in the Whetstone area. There were more male than female coyotes at FICO, but sex ratios were not different from 1:1 at Roisland and Whetstone. The visitation rates of coyotes, lagomorphs, and small mammals fluctuated greatly during this study. Monthly visitation rates of coyotes differed significantly, but annual and daily rates did not. The visitation rates of both lagomorphs and small mammals were significantly different between years and among months, but not among days. Lagomorph and small mammal visitation increased significantly after the trapping of coyotes and the end of the FICO carrion supply in the summer of 1976. Coyote visitation appeared to decrease after the summer of 1976. Prior to the summer of 1976, the visitation rates of coyotes and lagomorphs were positively correlated, but the rates of coyotes and small mammals were not correlated. After the summer of 1976, coyote visitation was negatively correlated with both lagomorph and small mammal visitation. The distribution of coyote and lagomorph visits along the scent station line did not change after the summer of 1976. Small mammal visitation, however, increased in the distant section of the line after the summer of 1976. Coyotes visited stations located on the upwind side of the road more frequently than they stopped at stations on the downwind side. Lagomorphs showed no preference for either side of the road, but small mammals visited more stations on the downwind side of the road than on the upwind side. The breeding rate at FICO did not decrease after the carrion supply ended. It seems unlikely, therefore, that the high breeding rate at FICO was caused by feeding on carrion. The scent station technique has potential as a means of monitoring the monthly relative abundance of coyotes and certain prey groups. Unfortunately, visitation is a function of animal numbers and activity. Further research is required to quantify the relationship between visitation and abundance for each animal group.

The present study utilizes survey data (n = 415) collected in the Migrant Border Crossing Study from repatriated Mexican migrants to examine three important questions regarding unauthorized migration attempts through southern Arizona. First, what factors explicate migrants' modes of crossing? Second, do coyote fees vary among people who rely on smuggling services to cross the border? If so, what accounts for this variation? Third, what factors shape encounters with bajadores while traversing the desert? The present analyses expand on previous studies examining the unauthorized crossing in multiple ways. For instance, I empirically test the role of a "culture of migration" in explaining modes of crossing, coyote fees, and bajador encounters. I also differentiate between two main types of coyotes: "border business" and "interior." I then examine whether crossing with a coyote mediates the risk of encountering bajadores during the journey. Overall, there are important differences in crossing modes and coyote fees. Women are more likely to travel with both coyote types, while the opposite is true for more experienced migrants. Older migrants and people who cross during summer months are less likely to travel with an "interior" coyote. The strongest predictor of higher smuggling fees is the region of a person's U.S. destination. Higher coyote fees are also associated with immigrants' higher educational attainment, being married, being the sole economic provider for one's household, and higher household income. More experienced migrants, and those crossing in larger groups or during the summer also pay higher fees, however fees do not vary by gender, age, or social capital. These findings are somewhat consistent with the extant literature on human capital and risk tolerance/aversion, but run counter to the vast migration literature emphasizing the importance of social capital in the migration process. Finally, the risk of encountering bajadores is not higher for males, young adults, the less educated, and the more impoverished, which contradicts extant findings in the victimology literature. With the exception of crossing corridor and time spent in the desert, no other factors increase the risk of encountering bandits more than traveling with a coyote. Implications and possible future research are discussed.

Thesis (M.A.)--University of Montana, 2008. / Title from title screen. Description based on contents viewed Aug. 7, 2008. Includes bibliographical references (p. 110-123).

Thèses (M.A.)--Université de Sherbrooke (Canada), 1999. / Titre de l'écran-titre (visionné le 20 juin 2006). Publié aussi en version papier.

Water is essential to life. Three general forms of water exist: pre-formed water that is available in food, metabolic water that is created as a byproduct of life processes (e.g., metabolism of fat or breakdown of carbohydrates), and free water (i.e., water available for drinking). As humans settle arid environments, the addition of man-made free water sources (e.g., sewage ponds, catchment ponds) often occurs. In addition, a tool commonly used to increase the abundance or distribution of wildlife species in desert environments is the addition of water sources, usually specifically designed to benefit game species like bighorn sheep (Ovis canadensis), mule deer (Odocoileus hemionus), and chukar partridge (Alectoris chukar). In recent decades, some scientists have argued that adding water sources to deserts may have little to no effect on desert species because they are adapted to living in desert conditions, and have thus evolved to obtain their water needs in preformed and/or metabolic form. Scientists have also suggested that adding water sources to desert environments may actually harm some individual species and alter the arraignments of groups of similarly related species, known as communities. I conducted four studies at the U.S. Army Dugway Proving Ground to determine if man-made water sources have an influence on the rodent community, jackrabbits, and the canid community at the U.S. Army Dugway Proving Ground, Utah. I found that turning off water sources had no effect on abundance of rodent communities or jackrabbits. I found that a portion of coyotes used water sources and coyotes were only slightly less common near water sources once they were turned off. In addition, a portion of coyotes rarely or never drink from water sources and that coyotes did not leave their territories if water sources accessible to them were turned off. My final study revealed that turning off water sources did not influence kit fox survival or abundance, and that kit fox territories differed from areas associated with water sources in several key environmental characterizes, which may suggest that areas associated with water sources were not historically used by kit foxes. In summary, these findings suggest that water developments have little impact on the species that I studied.

This study examined the activity patterns and social relation ships between individuals in a large herd of domestic sheep (Ovis aries) in an effort to determine if behavioral characteristics predisposed certain individuals to coyote (Canis latrans) predation. The research was conducted on the Cook Ranch near Florence, Montana, from March through September of 1975. Data were collected from a herd of 627 ewes and 1082 lambs, each individually identifiable. A random sample of 44 ewes and their 75 lambs were intensively studied over a 16-wk period to establish activity budgets and the relationships between sheep activity and vulnerability to coyote predation. The feasibility of creating target lambs in a free-ranging environment by altering movement, appearance, or social relationships with other herd members was examined in six experiments. During the study, 24 ewes and 47 lambs died from natural causes. Predators killed 7 ewes and 73 lambs. Coyotes selected single lambs, lambs displaying aberrant movement, and lambs whose dams had restricted mobility. Reduced mobility appeared to increase the probability of a lamb being on the periphery of the bedground and this in turn increased the probability of it being encountered by an attacking coyote. Grazing and resting periods of lambs were highly correlated with those of the ewes. Lambs were not within sight of their dams 30 percent of the time and showed a greater tendency to be absent during rest periods than during other activity periods. Yearling ewes investigated less and won less encounters. Brocatelface ewes grazed less and slept more than whiteface ewes. The oldest ewes interacted with other members of the herd less than younger ewes. Although significant differences in behavior existed between different age and genotype cl asses, the behavior of ewes whose lambs were killed by coyotes was remarkably similar to all other ewes. Male lambs were consistently absent from their dams less than female lambs. Single lambs also showed a tendency to be with the ewe more than twins. Single lambs spent more time nursing than twins during the first half of the study but not the last half. Siblings that were killed by coyotes consistently lay down less than their litter mates. Although differences existed in the behavioral signature of various classes of lambs, no relationships between these differences and vulnerability to predation was apparent. / coyote predation on domestic sheep seems to be related more to the chance of a lamb being on the periphery of the bedground than to differences in behavioral signatures. No pairwise associations were found between ewes. Yearling ewes associated with other yearling ewes and were peripheral individuals both during the day and on the bedground. Brocatelface ewes were peripheral during the day, but not on the bedground. Statistically, yearling ewes were leaders, but leadership in a welfare sense did not exist. The general lack of file formations and the rolling pattern of files when files were formed suggests that leadership in domestic sheep is not a robust phenomenon. The influence of dominance on positional behavior observed during the study was reflected in strange-lamb experiments. Lambs which were unfamiliar with the herd were subordinate and were forced into peripheral positions where they were more vulnerable to predation for up to 3 weeks. ' Lambs with a high susceptibility to coyote predation can be created by simply raising lambs in isolation and later releasing them into a herd.