987 resultados para Predator


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In Hawaii, invasive plants have the ability to alter litter-based food chains because they often have litter traits that differ from native species. Additionally, abundant invasive predators, especially those representing new trophic levels, can reduce prey. The relative importance of these two processes on the litter invertebrate community in Hawaii is important, because they could affect the large number of endemic and endangered invertebrates. We determined the relative importance of litter resources, represented by leaf litter of two trees, an invasive nitrogen-fixer, Falcataria moluccana, and a native tree, Metrosideros polymorpha, and predation of an invasive terrestrial frog, Eleutherodactylus coqui, on leaf litter invertebrate abundance and composition. Principle component analysis revealed that F. moluccana litter creates an invertebrate community that greatly differs from that found in M. polymorpha litter. We found that F. moluccana increased the abundance of non-native fragmenters (Amphipoda and Isopoda) by 400% and non-native predaceous ants (Hymenoptera: Formicidae) by 200%. E. coqui had less effect on the litter invertebrate community; it reduced microbivores by 40% in F. moluccana and non-native ants by 30% across litter types. E. coqui stomach contents were similar in abundance and composition in both litter treatments, despite dramatic differences in the invertebrate community. Additionally, our results suggest that invertebrate community differences between litter types did not cascade to influence E. coqui growth or survivorship. In conclusion, it appears that an invasive nitrogen-fixing tree species has a greater influence on litter invertebrate community abundance and composition than the invasive predator, E. coqui.

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During autumn 2003, several thousand European starlings (Sturnus vulgaris) began roosting on exposed I-beams in a newly constructed, decorative glass canopy that covered the passenger pick-up area at the terminal building for Cleveland Hopkins International Airport, Ohio. The use of lethal control or conventional dispersal techniques, such as pyrotechnics and fire hoses, were not feasible in the airport terminal area. The design and aesthetics of the structure precluded the use of netting and other exclusion materials. In January 2004, an attempt was made to disperse the birds using recorded predator and distress calls broadcast from speakers installed in the structure. This technique failed to disperse the birds. In February 2004, we developed a technique using compressed air to physically and audibly harass the birds. We used a trailer-mounted commercial air compressor producing 185 cubic feet per minute of air at 100 pounds per square inch pressure and a 20-foot long, 1-inch diameter PVC pipe attached to the outlet hose. One person slowly (< 5 mph) drove a pick-up truck through the airport terminal at dusk while the second person sat on a bench in the truck bed and directed the compressed air from the pipe into the canopy to harass starlings attempting to enter the roost site. After 5 consecutive nights of compressed-air harassment, virtually no starlings attempted to roost in the canopy. Once familiar with the physical effects of the compressed air, the birds dispersed at the sound of the air. Only occasional harassment at dusk was needed through the remainder of the winter to keep the canopy free of starlings. Similar harassment with the compressor was conducted successfully in autumn 2004 with the addition of a modified leaf blower, wooden clappers, and laser. In conclusion, we found compressed air to be a safe, unobtrusive, and effective method for dispersing starlings from an urban roost site. This technique would likely be applicable for other urban-roosting species such as crows, house sparrows, and blackbirds.

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Insect pollination is an essential ecosystem service, and bees are the principal pollinators of wild and cultivated plants. Habitat management and enhancement are a proven way to encourage wild bee populations, providing them with food and nesting resources. I examined bee diversity and abundance in plots managed by The Nature Conservancy near Wood River, NE. The plots were seeded with 2 seed mixes at 2 seeding rates: high diversity mix at the recommended rate, high diversity mix double the recommended rate, Natural Resources Conservation Service (NRCS) conservation planting (CP) 25 mix at one-half the recommended rate, and NRCS CP25 mix at the recommended rate. I measured wild bee abundance and diversity, and established a database of wild bees associated with the plots. I also compared genus richness and abundance among the plots using and aerial net and blue vane traps to collect bees. Significant differences were not observed in genus richness and diversity among the plots; however, plot size and the ability of blue vane traps to draw bees from a long distance may have influenced my results. In 2008, 15 genera and 95 individual bees were collected using an aerial net and in 2009, 32 genera and 6,103 individual bees were collected using blue vane traps. I also studied the beneficial insects associated with native Nebraska flora. Seventeen species of native, perennial flora were established in 3 separate plots located in eastern Nebraska. I transplanted four plants of each species in randomized 0.61 m x 0.61 m squares of a 3.05 m x 9.14 m plot. Arthropods were sampled using a modified leaf blower/vacuum. Insects and other arthropods were identified to family and organized into groups of predators, parasites, pollinators, herbivores, and miscellaneous. Associations between plant species and families of beneficial arthropods (predators, parasites, and pollinators) were made. Pycnanthemum flexuosum Walter attracted significantly more beneficial arthropod families than 7 other species of plants tested. Dalea purpurea Vent and Liatris punctata Hook also attracted significantly fewer beneficial arthropod families than 4 other species of plants tested. In total, 31 predator, 11 parasitic, 4 pollinator, 31 herbivore, and 10 miscellaneous families of arthropods were recorded.

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The northern biotype of Echinococcus granulosus occurs throughout the holarctic zones of tundra and taiga, from eastern Fennoscandia to the Bering Strait in Eurasia and in North America from arctic Alaska approximately to the northern border of the United States. The cycle of the cestode is complex in taiga at lower latitudes, because of the greater diversity of potential hosts. In the Arctic and Subarctic, however, four patterns of predator/prey relationships may be discerned. Two natural cycles involve the wolf and wild reindeer and the wolf and elk (moose), respectively. Where deer of the two species coexist, both are prey of the wolf; the interactions of the wolf and elk are here described on the basis of long-term observations made on Isle Royale (in Lake Superior near the southern limit of taiga), where only the wolf and elk serve as hosts for E. granulosus. A synanthropic cycle involving herding-dogs and domesticated reindeer caused hyperendemicity of cystic echinococcosis in arctic Eurasia, mainly in northeastern Siberia. The 4th pattern, a semi-synanthropic cycle, formerly existed in Alaska, wherein sled-dogs of the indigenous hunters became infected by consuming the lungs of wild reindeer. The sequence of changes in life-style inherent in the process of acculturation affected the occurrence of cystic echinococcosis among nomadic Iñupiat in arctic Alaska. When those people became sedentary, the environs of their early villages soon became severely contaminated by feces of dogs, and cases of cystic echinococcosis occurred. Compared to cystic echinococcosis caused by E. granulosus adapted to synanthropic hosts (dog and domestic ungulates), the infection produced by the northern biotype is relatively benign. 0fearly all diagnosed cases of cystic echinococcosis (> 300 in Alaska have occurred in indigenous people; only one fatality has been recorded (in a non-indigenous person). After sled-dogs were replaced by machines, cases have become rare in Alaska. A similar effect has been observed in Fennoscandia, in the Saami and domesticated reindeer. Recent records indicate tbat the prcvalence of cystic echinococcosis is increasing in Russia, suggesting that dogs are used there in herding.

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In 1986, the U.S. Environmental Protection Agency (EPA) initiated an effort to comply more fully with the Endangered Species Act. This effort became their "Endangered Species Protection Program." The possibility of such a program was forecast in 1982 when Donald A. Spencer gave a presentation to the Tenth Vertebrate Pest Conference on "Vertebrate Pest Management and Changing Times." This paper focuses on current plans for implementing the EPA's Endangered Species Protection Program as it relates to the USDA Forest Service. It analyzes the potential effects this program will have on the agency, using the pocket gopher (Thomomys spp.), strychnine, and the grizzly bear (Ursus arctos horribilis) as examples of an affected pest, pesticide, and predator.

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In reviewing methods of predator control, it would first seem appropriate to define what is meant "by "methods" and what is meant by "control." Taking the last term first, control, as applied to the predatory coyotes, bobcats, and foxes, may be defined as regulating the numbers of these animals to the point where the economic losses for which they are responsible will be reduced to a practicable minimum. In some situations, area control, i.e., limiting the numbers of the offending predator over wide areas, may be necessary for satisfactory reduction of economic losses; in other situations, spot control or localized reduction of numbers of a certain predator may be called for; in still other situations, elimination of an individual animal may be all the control that is needed. In no sense is control, as applied to coyotes, bobcats, and foxes, intended to mean extermi¬nation of a species. The term "methods" is interpreted as meaning the procedures employed against coyotes, bobcats, and foxes, and not the broader systems of predator control such as the paid hunter system, the extension system, or the much-discredited bounty system. For an excellent review of the systems of predator control, see Latham (l).

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Up to 1949, the Fish and Game Branch employed personnel, some of whom were temporary, to attempt control of the extremely high wolf pop¬ulations of the central and northern portions of British Columbia. Coyotes were also very numerous in the central and southern regions and had to be considered because of their depredations. The field men were keen and conscientious but their efforts were not co-ordinated. Control areas were severely restricted in size as techniques were not adaptable enough and because of a lack of manpower. Eventually, sheepmen went out of business entirely over wide areas, cattlemen were subjected to huge annual losses, and sportsmen were very concerned. However, stock losses constituted the major complaint and resulted in ranchers demanding action* Two major changes came out of this. First, the bounty on wolves was raised and second, the present Predator Control Division was formed. The administration was convinced that a force of experienced, fully-trained field staff under a single supervision would be far more effective than bounty payments. Unfortunately, bounties were in vogue during that time and forced the necessity of proving the worth of organized controls before any consideration could be given to the elimination of the bounty system.

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The coyote (Canis latrans) is among the most studied animals in North America. Because of its adaptability and success as a predator, the coyote has flourished and is still expanding its range. Coyotes can now be found throughout most of North America and south into Central America (Voight and Berg 1987). Studies in recent years have been extensive to understand the interrelationships of prey and coyotes (Shelton and Klindt 1974, Beckoff and Wells 1981), as well as demographic relationships (Davis et al. 1975, Knowlton and Stoddart 1978, Mitchell 1979, Bowen 1981) and feeding strategies (Todd and Keith 1976, Andelt et al. 1987, MacCracken and Hansen 1987, Gese et al. 1988a). With the advance of radio telemetry, researchers have investigated lifestyle characteristics spatially with home ranges or temporally with movements in relation to habitat requirements. Researchers have studied home ranges of coyotes in various regions of the United States (Livaitis and Shaw 1980, Andelt 1981, Springer 1982, Pyrah 1984, Gese et al. 1988a) and Canada (Bowen 1982). Some studies of home range were separated by season (Ozoga and Harger 1966) or relation to nearby food sources (Danner and Smith 1980). Home range analysis in relation to social interactions of coyotes has been either neglected, overlooked, or avoided. Gese et al. (1988a) recognized a transient class of coyote by home range size. Coyote social systems are very complex and can vary by season or locality in addition to some reports of group or pack systems (Hamlin and Schweitzer 1979, Beckoff and Wells 1981, Bowen 1981, Gese et al. 1988b). Coyotes maintain communication with conspecifics through vocal and olfactory signals (Lehner 1987, Bowen and McTaggert Cowan 1980). Social interactions may be by far the most complex and least understood aspect related to coyote ecology. Coyote movements can be related to many factors including food, water, cover, and social interactions. Movements in relation to food sources are well documented (Fitch 1948, Todd and Keith 1976, Danner and Smith 1980) although reports on movements in relation to water have not been reported, probably because of limited research in desert situations. There has been some mention of coyotes' movements in relation to cover (Wells and Beckoff 1982). The objectives of this study were to delineate annual and seasonal home ranges, movements, and habitat use of coyotes in the northern Chihuahuan desert.

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Wildlife Damage Conferences: When, Where, and Why? -- Robert M. Timm, Editor, THE PROBE Booklet Review:"The Problem with Skunks!!" by Edward Kellems (34 pages, illustrated. $14.95) New NWCO Web Page url is http://www.wildlifedamagecontrol.com/nwcoa.htm Abstracts from the 2nd International Wildlife Management Congress, Hungary Human Disturbance as a Design Factor to Aid Displacement of Canada Geese from Urban Parks -- P. C. Whitford, Biology Department, Capital University, Columbus, OH Leopard Problems in Nepal -- T. M. Maskey, National Parks and Wildlife Conservation Department, Kathmandu, Nepal Elk-human Conflict Management in Banff National Park, Alberta, Canada -- J. A. McKenzie, Banff National Park Wildlife Laboratory The Avoidance of Virtual Barriers by Wolves in Captivity -- M. Musiani*, E. Visalberghi*, andL. Boitani, *CNR Psychology Institute, Rome, Italy Successful Field Trials of a New Slow-Release Capsaicin-Based Animal Repellent for Reducing a Variety of Human-Wildlife Conflicts in Israel -- S. C. Nemtzov, Dept. of Terrestrial Ecology, The Nature and National Parks Protection Authority, Jerusalem, Israel Educational Workshops: A Proactive Approach to Conflict Resolution in Wildlife Management -- K. B. Reis, H. R. Campa III, R. B. Peyton, and S. Winterstein, Dept. of Fisheries & Wildlife, Michigan State University, East Lansing, MI Traps and Trapping in Sweden -- T. Svensson, Swedish Environmental Protection Agency, Stockholm, Sweden Actual Problems of Predator Management in Hungary -- L. Szemethy, M. Heltai, and Z. Biro, Dept. of Wildlife Biology & Management, Godollo University of Agricultural Sciences, Godollo, Hungary Crop and Livestock Depredation by Wildlife -- N. Udaya Sekhar, Centre for Int'I. Environment & Development Studies, Aas, Norway Conservation of the Iberian Wolf in Portugal—The Everlasting Conflict with Man -- J. V. Vingada*, C. Eira, S. Scheich, C. Fonseca, M. Soares, F. L. Correia, M. Fana* P. Carmo, A. Ferreira, A. Soares, and B. Bobek. *Dept. deBiologia da Universidade do Minho, Campus de Gualtar, Portugal Barkpeeling Damage in Relation to Red Deer Density and Forest Structure in Austria -- F. H. Voelk, Institute of Wildlife Biology & Game Management, Universitaetfuer Bodenkultur Wien, Vienna, Austria Human-Wildlife Conflict Resolution: National Imperatives and Strategies -- P. 0. Wander a Kenya Wildlife Service, Nairobi, Kenya An Overview and Evaluation of Deer Herd Management Programs in Urban and Suburban Communities of the USA -- R. J. Warren, Warnell School of Forest Resources, Univ. of Georgia, Athens, GA

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As you can see from the general tenor of the printed program for this seminar, I am in the unenviable position of trying to discourage you from certain types of chemical control; but my assigned topic "Side Effects of Persistent Toxicants," implies that mission. However, my remarks may be somewhat anticlimax at this time, because it is now generally conceded that we need to reevaluate certain chemicals in control work and to restrict or severely curtail use of those that per¬sist for long periods in the environment. So let me detail my reasons for a somewhat negative attitude toward the use of the persistent hydrocarbons from my experience with the effects of these materials on birds. But first a few words of caution about control work in general, which so often disrupts natural processes and leads to new and unforseen difficulties. As an example, I think of the irruption of mice in the Klamath valley in northern California and southern Oregon in the late '50's. Intensive predator control, particularly of coyotes, but also of hawks and owls, was followed by a severe outbreak of mice in the spring of 1958. To combat the plague of mice, poisoned bait (1080 and zinc phosphide) was widely distributed in an area used by 500,000 waterfowl each spring. More than 3,000 geese were poisoned, so driv¬ing parties were organized to keep the geese off the treated fields. Here it seems conceivable that the whole chain of costly events--cost of the original and probably unnecessary predator control, economic loss to crops from the mouse outbreak, another poisoning campaign to combat the mice, loss of valuable waterfowl resources, and man-hours involved in flushing geese from the fields--might have been averted by a policy of not interfering with the original predator-prey relationship. This points to a dilemma we always face. (We create deplorable situations by clumsy interference with natural processes, then seek artificial cures to correct our mistakes.) For example, we spend millions of dollars in seeking cures for cancer, but do little or nothing about restricting the use of known or suspected carcinogens such as nicotine and DDT.

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• Suburban Invasion! By Wildlife? -- Michelle L. Shuey, Southwest Texas State University • What are the health risks of consuming meat from deer or elk infected with Chronic Wasting Disease ? • The 68th North American Wildlife and Natural Resources Conference is set for March 26-30, 2003, in Winston-Salem, North Carolina • Book Review: Living in the Shadows: How to Help the Stray Cat in Your Life (Without Adding to the Problem) by Ann K. Fisher.--“I was impressed with her chapter on taming feral cats. It would certainly take a dedicated soul to put that much work into taming a cat.” • Goose School: the first National Goose Management Training Academy in Indianapolis, Indiana (June 8 & 9, 2002) -- Larry Sullivan • The California Contractors State License Board, (CSLB), recently approved a new sub-classification in its Non-Specialty Contractors License category. The new license is listed as C-61/D-64 "Animal Damage and Bird Control". • Los Angeles animal control recently approved increased efforts to control coyotes in residential areas by using traditional deterrent programs. • Identifying Predator Kills: Texas A&M has a website with some excellent photos to help identify predator kills of livestock. See http://texnat.tamu.edu/ranchref/predator/p-gen.htm • History of Wolf Attacks in Europe and Asia -- Barton Stam, Utah State University

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The feeding ecology of the Brazilian silverside, Atherinella brasiliensis, in a sub-tropical estuary of Brazil was investigated through the gut analysis of 1431 individuals. We described dietary composition and analysed seasonal, estuarine habitat, and body size variations in the diet; trophic level; feeding diversity; and gut fullness indices. Results reveal that A. brasiliensis is a typical, generalistic and opportunistic predator that makes use of a wide array of prey types (at least 89 different types), with zooplankton (mainly calanoids), diatoms, terrestrial insects, and plant detritus making up the bulk of the overall diet. The exotic calanoid Temora turbinata ranked as the primary prey. A wide feeding diversity (mean H` = 2.26), low trophic level (mean TROPH = 2.57), and high gut replenishment were persistent across seasons and habitats. Diet composition varied largely and significantly with respect to habitat, season, and body size. A closer assessment showed that habitat and season had a stronger effect on diet than fish size.

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Animals present an enormous variety of behavioural defensive mechanisms, which increase their survival, but often at a cost. Several animal taxa reduce their chances of being detected and/or recognized as prey items by freezing (remaining completely motionless) in the presence of a predator. We studied costs and benefits of freezing in immature Eumesosoma roeweri (Opiliones, Sclerosomatidae). Preliminary observations showed that these individuals often freeze in the presence of the syntopic predatory spider Schizocosa ocreata (Araneae, Lycosidae). We verified that harvestmen paired with predators spent more time freezing than when alone or when paired with a conspecific. Then. we determined that predator chemical cues alone did not elicit freezing behaviour. Next, we examined predator behaviour towards moving/non-moving prey and found that spiders attacked moving prey significantly more, suggesting an advantage of freezing in the presence of a predator. Finally, as measure of the foraging costs of freezing, we found that individuals paired with a predator for 2 h gained significantly less weight than individuals paired with a conspecific or left alone. Taken together, our results suggest that freezing may protect E. roeweri harvestmen from predatory attacks by wolf spiders, but at the cost of reduced food and/or water intake. (C) 2009 Elsevier B.V. All rights reserved.

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This study documents one of the slowest feeding behaviors ever recorded for a muricid gastropod in one of the most biotically rigorous regions on the planet. In Pacific Panama, Vitularia salebrosa attacks mollusks by drilling through their shells. The duration of attacks estimated by isotope sclerochronology of oyster shells collected during attacks in progress range from 90 to 230 days, while experimental observation of interactions documented one attack greater than 103 days. The prolonged nature of attacks suggests that V. salebrosa is best characterized as an ectoparasite than as a predator, which is the ancestral condition in the Muricidae. An ectoparasitic lifestyle is also evident in the unusual interaction traces of this species, which include foot scars, feeding tunnels and feeding tubes, specialized soft anatomy, and in the formation of male-female Pairs, which is consistent with protandrous hermaphroditism, as is typical in sedentary gastropods. To delay death of its host, V. salebrosa targets renewable resources when feeding, such as blood and digestive glands. A congener, Vitularia miliaris from the Indo-Pacific, has an identical feeding biology The origin and persistence of extremely slow feeding in the tropics challenges our present understanding of selective pressures influencing the evolution of muricid feeding behaviors and morphological adaptations. Previously, it has been suggested that faster feeding is advantageous because it permits predators to spend a greater proportion of time hiding in enemy-free refugia or to take additional prey, the energetic benefits of which could be translated into increased fecundity or defenses. The benefits of exceptionally slow feeding have received little consideration. In the microhabitat preferred by V. salebrosa (beneath boulders), it is possible that prolonged interactions with hosts decrease vulnerability to enemies by reducing the frequency of risky foraging events between feedings . Ectoparasitic feeding through tunnels by V. salebrosa may also reduce competitive interactions with kleptoparasites (e.g., crabs, snails) that steal food through the gaped valves of dead or dying hosts.