The Role of Scavenging in Disease Dynamics

Contents Introduction................ 161 The Use of Animal Remains and the Exposure of Scavengers to Disease........ 163 The Relevance of Scavenging for Pathogens to Spread and Persist.......... 166 Human Related Factors Resulting in Increased Risk for Disease Transmission Through Scavenging.............. 170 Management of Scavenging to Reduce Disease Risks.............. 173 Restoration of Large Predators.................. 174 Elimination of Hunting of Scavengers............ 174 Destruction of Big Game and Domestic Animal Carcasses........... 174 Restoration of the Effects of Overabundance............. 175 Excluding Mammalian and Avian Scavengers from Natural Carrions.......... 176 Excluding Mammalian and Avian Scavengers from Vulture Restaurants........... 176 Conclusions and Future Perspectives........... 178 References............... 17

Invasives: The High Cost of Indifference

At one time, wildlife professionals may have been blissfully ignorant about invasive species, classifying “plants” as lawn grass, flowers, trees, or weeds, and putting animals into two groups: species with bag limits and everything else. But those days of ignorance are long past. We see how invasives threaten local, even global, ecosystems, and we need to help create greater awareness about the scope of the problem. Wildlife professionals must not only prepare to deal with how seven billion people, climate change, and habitat loss will affect native species and habitats, but also how those species and habitats will be affected by a host of invasive plants, animals, and pathogens. While we try to sort out the science, we must also lead by educating a public that may be indifferent

Understanding Vole Problems in Direct Seeding — Strategies for Management

Crop fields can provide habitat to a variety of wildlife and crop damage can result (Wywialowski 1996, 1998; Conover 1998). Among the vertebrates, damage can occur from numerous species of birds and mammals. Worldwide concern, however, has focused on rodents and a large number of species cause substantial agricultural losses each year (Witmer et al. 1995). After the advent of effective herbicides and clean farming practices in North America, however, many rodent problems became insignificant (Hines and Hygnstrom 2000). This is, in large part, because the fields were plowed each year, disrupting burrows and removing ground cover. The fields often lay bare a lengthy part of the year. The use of herbicides, plowing, and burning prevented the fields from developing the vegetative cover that wildlife needed for year-round food and shelter. This situation has been changing in recent years. The use of conservation tillage or no-till agriculture is increasing across much of North America, in part because these methods conserve soil and water resources. Many problems can arise, however, and an integrated pest management strategy is needed to deal with weed, insect, and vertebrate pests that can proliferate and cause substantial damage in the no-till agriculture setting (Holtzer et al. 1996). When the ground is not plowed each year, crop residues are maintained, and surrounding areas provide good harborage for rodents, the potential exists for substantial increases in rodent populations and subsequent crop damage. The microtine species group (Subfamily Microtinae, Nowak 1991) contains many species that are serious pests throughout the northern hemisphere. In North America, many of the pest species belong to the genus Microtus, commonly called voles or meadow mice. In this paper, we review the literature and provide background information on voles and the damage they cause. We also discuss management strategies that can help reduce agricultural damage by voles

A review of color vision in white-tailed deer

A better understanding of the color vision abilities of white-tailed deer (Odocoileus virginianus) helps to determine how these animals interpret their environment. We review and summarize the literature related to the color vision abilities of white-tailed deer. Physiological measurements using advanced techniques such as molecular genetics, electroretinography, and electron microscopy have demonstrated conclusively that whitetailed deer possess the anatomical requisites for color vision. Operant conditioning techniques employed in pen studies using trained cervids confirm that deer see color. The eyes of white-tailed deer are characterized by 3 classes of photopigments: a short-wavelengthsensitive cone mechanism, a middle-wavelength-sensitive cone mechanism, and a short wavelength- sensitive rod pigment. The number and distribution of rod, and cones in the retina, augmented by adaptations of the eye, give white-tailed deer high visual sensitivity and visual acuity in light and darkness. During the day deer discriminate colors in the range blue to yellow-green and can also distinguish longer (orange and red) wavelengths. At night deer see color in the blue to blue-green range, although the moderately wide spectral sensitivity of rods permits some discrimination of longer wavelengths. Rods serve a discriminatory role in color vision, especially at low to moderate illumination levels. Benefits of color vision to deer include the ability to discriminate between plant species and parts and enhanced predator-detection capabilities. This information can be used to define methods of resolving deer-human conflicts and provide insight to deer researchers, photographers, and hunters on how to he more inconspicuous to their subject

Fencing Methods to Reduce Deer Damage

The white-tailed deer (Odocoifeus virginianus) may cause more damage than any other wildlife species. Deer damage occurs in various forms including crop production, automobile accidents, aviation collisions on runways, disease transmission, degradation of natural ecosystems, and destruction of ornamental plantings. One practical method of controlling deer damage is through the use of exclusionary fencing. White-tailed deer are challenging to exclude as they are able to jump 3.0-m fences or fit through spaces \u3e 20 cm wide. Some deer problems (disease outbreaks, aircraft runways, and busy highways in deer migration corridors) may necessitate the installation of effective fencing no matter what the cost. Fences most often installed to control white-tailed deer damage include, but are not limited to, many varieties and types of wire mesh, plastic mesh, high-tensile steel wire, and electric fence. We have reviewed scientific literature on fencing to compare fence designs and methods to predict which are best suited for excluding deer under a variety of conditions. In situations where a nearly impenetrable, low maintenance, long-life fence is needed, a 3.0-3 64 m-high wire mesh fence is the best option. If complete exclusion is not a necessity and fence cost is an issue, a multi-strand, electrified, high-tensile steel wire fence may be sufficient. For seasonal protection, an affordable, easily installed, peanut butter fence may be adequate. Each fencing application will require consideration of different factors for determining the most appropriate fence, requiring a thorough comparison of available options to assist in the decision making process. The most important considerations for determining the best fence for a specific application include: level of protection desired from the fence, deer\u27s ability to penetrate different fence designs, motivation to penetrate a fence, costs associated with a fence, and possible negative effects of erecting a fence. Fencing may be only part of the answer to a deer damage issue. An integrated management approach may increase the overall efficacy of any individual damage reduction method, including fencing. With abundant white-tailed deer populations, recent disease outbreaks, increasing vehicle collisions, and increased urbanization, there is an increasing need for effective deer-damage management tools. There are many research needs in the area of wildlife exclusion. Few rigorous tests of the efficacy of different fence designs have been conducted. Efficacy levels of any specific fence design are difficult to establish due to the multitude of interacting variables determining how an animal will respond to a particular fence design. Most, if not all, of the scientific testing conducted to date has been directed at excluding animals. However, means of confining captive deer are also of importance

Deer Population Management Through Hunting in a Suburban Nature Area in Eastern Nebraska

The Fontenelle Forest Nature Area (FF) maintained a hands-off management policy for 30 years until it was recognized that white-tailed deer (Odocoileus virginianus) populations had grown to such levels that they were severely degrading native plant communities. In 1995, members of a community task force decided to sponsor annual nine-day hunting seasons on FF after learning that densities exceeded 28 deer/km2. Archers harvested 85 antlerless deer in the FF upland areas adjacent to residential Bellevue, Nebraska during 1996 to 1998. Muzzleloader hunters removed 53 antlerless deer from the FF lowland areas. Archery and muzzleloader hunters harvested 297 deer during the same period in Gifford Point (GP), a state-owned wildlife management area adjacent to the FF lowlands. Overall deer densities declined from 28 deer/km2 in 1995 to 14 deer/km in 1998. Densities were at or near over-winter goals in all areas by 1998, except for the unhunted residential area, which still maintained 20 deer/km. Annual survival rates for radio-marked adult and yearling female deer were 0.70 and 0.59, respectively. Archery was the primary mortality factor (20%) for radio-marked deer across years. Population models predict that densities would increase to 55 deer/km in five years if hunting seasons were abandoned in FF. Hunter behavior in FF has been reported as excellent and little public opposition exists

Movement responses inform effectiveness and consequences of baiting wild pigs for population control

Wild pigs (Sus scrofa) damage agricultural and natural resources throughout their nearly global distribution. Subsequently, population control activities (e.g., trapping, shooting, or toxic baiting) frequently involve the deployment of bait to attract wild pigs. A better understanding of how wild pigs respond to bait sites can help maximize efficiency of baiting programs and identify any potential pitfalls. We examined the movement behaviors of 68 wild pigs during three stages of intensive baiting programs (i.e., 15 days each: prior, during, and post baiting) spread across two distinct study areas in southern and northern Texas, USA. We found that bait sites needed to be within1 km of where females were located (1.25 km for males) to achieve 0.50 daily visitation rate. Deployment of bait increased movement distances and erratic movements for both sexes, but did not influence their foraging search area. Home range sizes increased and shifted during baiting, especially for wild pigs on the periphery of the baiting area. After baiting ceased, wild pigs moved away from bait sites and began using new space (i.e., less overlap with previously used home ranges), suggesting that baiting could facilitate the spread of wild pigs. We recommend that baiting programs should be coordinated to reduce the number of wild pigs left on the landscape following baiting. Bait sites should be spaced every 1–2 km, and should be actively relocated if visitation by wild pigs is not consistent. Uncoordinated and passive baiting for recreational hunting and trapping likely exacerbates the negative consequences of baiting identified in this study, such as expanding the space-use and facilitating the spread of wild pigs

Understanding Vole Problems in Direct Seeding-Strategies for Management

Crop fields can provide habitat to a variety of wildlife and crop damage can result (Wywialowski 1996,1998; Conover 1998). Among the vertebrates, damage can occur from numerous species of birds and mammals. Worldwide concern, however, has focused on rodents and a large number of species cause substantial agriculture losses each year (Witmer et al, 1995). After the advent of effective herbicides and clean farming practices in North America, however, many rodent problems became insignificant (Hines and Hygnstrom 2000). This is, in large part, because the fields were plowed each year, disrupting burrows and removing ground cover. The fields often lay bare a lengthy part of the year. The use of herbicides, plowing, and burning prevented the fields from developing the vegetative cover that wildlife needed for year-round food aid shelter. This situation has been changing in recent years. The use of conservation tillage or no-till agriculture is increasing across much of North America, in part because these methods conserve soil and water resources. Many problems can arise, however, and an integrated pest management strategy is needed to deal with weed, insect, and vertebrate pests that can proliferate and cause substantial damage in the no-till agriculture setting (Holtzer et al. 1996). When the ground is not plowed each year, crop residues are maintained, and surrounding areas provide good harborage for rodents, the potential exists for substantial increases in rodent populations and subsequent crop damage

Chapter 8 Keeping Wildlife Out of Your Food: Mitigation and Control Strategies to Reduce the Transmission Risk of Food-Borne Pathogens

In this chapter, we provide a general framework for developing strategies to mitigate the contamination of agricultural operations with pathogens carried by wildlife. As part of this framework, we present adaptive management as a viable approach to developing these strategies to reduce the uncertainty over time as to whether management methods are being effective. We provide the general steps to developing an adaptive management strategies as well as generic mitigation methods that can be applied to agricultural operations as part of an adaptive management strategy