{"id":3188,"date":"2020-09-25T01:37:58","date_gmt":"2020-09-25T01:37:58","guid":{"rendered":"http:\/\/nwco.net\/?page_id=3188"},"modified":"2020-09-25T01:37:58","modified_gmt":"2020-09-25T01:37:58","slug":"damage-identification","status":"publish","type":"page","link":"https:\/\/nwco.net\/?page_id=3188","title":{"rendered":"Damage Identification"},"content":{"rendered":"\n

Richard A. Dolbeer .<\/strong>Project Leader Denver. Wildlife Research Center USDA-APHIS- Animal Damage Control, Sandusky, Ohio 44870 <\/p>\n\n\n

Nicholas R. Holler .<\/strong>Unit Leader Alabama Cooperative Fish and Wildlife Research Unit , US Fish and Wildlife Service. Auburn, Alabama 36849 <\/p>\n\n\n

Donald W. Hawthorne .<\/strong>Associate Deputy Administrator SDA-APHIS-Animal Damage Control, Washington, DC 20090 <\/p>\n\n\n

IDENTIFICATION AND ASSESSMENT OF WILDLIFE DAMAGE: AN OVERVIEW<\/h2>\n\n\n

Introduction <\/h2>\n\n\n

Wildlife management is often thought of in terms of\nprotecting, enhancing, and nurturing wildlife populations and the habitat\nneeded for their well-being. However, many species at one time or another\nrequire management actions to reduce conflicts with people or with other\nwildlife species. Examples include an airport manager modifying habitats to\nreduce gull activity near runways, a forester poisoning pocket gophers to\nincrease tree seedling survival in a reforestation project, or a biologist\ntrapping an abundant predator or competing species to enhance survival of an\nendangered species. <\/p>\n\n\n

Wildlife damage control is an increasingly important part of\nthe wildlife management profession because of expanding human populations and intensified\nland-use practices. Concurrent with this growing need to reduce wildlife-people\nconflicts, public attitudes and environmental regulations are restricting use\nof some of the traditional tools of control such as toxicants and traps.\nAitle><\/title>\n\t\thttps:\/\/nwco.net\/training-modules\/site-inspection\/damage-identification\/<\/link>\n\t\tFri, 25 Sep 2020 01:37:58 +0000<\/pubDate>\n\t\t<\/dc:creator>\n\t\thttps:\/\/nwco.net\/?page_id=3188<\/guid>\n\t\t<\/description>\n\t\tRichard A. Dolbeer .<\/strong>Project Leader Denver. Wildlife Research Center USDA-APHIS- Animal Damage Control, Sandusky, Ohio 44870 <\/p>\n\n\n

Nicholas R. Holler .<\/strong>Unit Leader Alabama Cooperative Fish and Wildlife Research Unit , US Fish and Wildlife Service. Auburn, Alabama 36849 <\/p>\n\n\n

Donald W. Hawthorne .<\/strong>Associate Deputy Administrator SDA-APHIS-Animal Damage Control, Washington, DC 20090 <\/p>\n\n\n

IDENTIFICATION AND ASSESSMENT OF WILDLIFE DAMAGE: AN OVERVIEW<\/h2>\n\n\n

Introduction <\/h2>\n\n\n

Wildlife management is often thought of in terms of\nprotecting, enhancing, and nurturing wildlife populations and the habitat\nneeded for their well-being. However, many species at one time or another\nrequire management actions to reduce conflicts with people or with other\nwildlife species. Examples include an airport manager modifying habitats to\nreduce gull activity near runways, a forester poisoning pocket gophers to\nincrease tree seedling survival in a reforestation project, or a biologist\ntrapping an abundant predator or competing species to enhance survival of an\nendangered species. <\/p>\n\n\n

Wildlife damage control is an increasingly important part of\nthe wildlife management profession because of expanding human populations and intensified\nland-use practices. Concurrent with this growing need to reduce wildlife-people\nconflicts, public attitudes and environmental regulations are restricting use\nof some of the traditional tools of control such as toxicants and traps.\nAgencies and individuals carrying out control programs are being more carefully\nscrutinized to ensure that their actions are justified, environmentally safe,\nand in the public interest. Thus, wildlife damage control activities must be\nbased on sound economic, ecological, and sociological principles and carried\nout as positive, necessary components of overall wildlife management programs. <\/p>\n\n\n

Wildlife damage control programs can be thought of as having\nfour parts: (1) problem definition; (2) ecology of the problem species; (3)\ncontrol methods application; and (4) evaluation of control. Problem definition\nrefers to determining the species and numbers of animals causing the problem,\nthe amount of loss or nature of the conflict, and other biological and social\nfactors related to the problem. Ecology of the problem species refers to\nunder-standing the life history of the species, especially in relation to the\nconflict. Control methods application refers to taking the information gained\nfrom parts 1 and 2 to develop an appropriate management program to alleviate or\nreduce the conflict. Evaluation of control allows an assessment of the\nreduction in damage in relation to costs and impact of the control on target\nand nontarget populations and the environment. Increasingly, emphasis is being\nplaced on integrated pest management whereby several control methods are\ncombined and coordinated with other management practices in use at that time. <\/p>\n\n\n

Birds <\/h2>\n\n\n

Damage Assessment <\/h3>\n\n\n

Birds annually\ndestroy many millions of dollars worth of agricultural crops in North America.\nThe greatest loss appears to be from blackbirds feeding on ripening corn; a\nsurvey in 1981 indicated a loss in the United States of 330,000 tons (300,000\nmetric tons) worth $31 million (Besser and Brady 1986). Blackbird damage to\nsunflower crops in the upper Great Plains states was estimated at $5 million in\n1979 and $8 million in 1980 (Hothem et al. 1988). Damage by various bird\nspecies to fruit crops, peanuts, truck crops, and small grains also can be\nsevere in localized areas (Besser 1986). Fish-eating birds can cause major\nlosses at fish rearing facilities. Economic losses from bird strikes to aircraft\nare per-haps more substantial than those in agriculture, at least $20 million\nannually each for US commercial air carriers (Steenblik 1983) and military\naircraft (Merritt 1990). <\/p>\n\n\n

Unlike most mammals,\nwhich are secretive when causing damage, birds are often highly visible and\ntheir damage conspicuous. For this reason, subjective estimates often\noverestimate losses as much as tenfold (Weather-head et al. 1982). Thus,\nobjective estimates of bird damage to agricultural crops are important in order\nto accurately define the magnitude of the problem and to plan appropriate,\ncost-effective control actions (Dolbeer 1981). <\/p>\n\n\n

To estimate losses\ndue to birds in agricultural crops, one must devise a sampling scheme to select\nthe fields that are to be examined and then determine the plants or areas to be\nmeasured in the selected fields (Stickley et al. 1979). For example, to\nobjectively estimate the amount of blackbird damage in a ripening corn or\nsunflower field, the estimator should examine at least 10 locations widely spaced\nin the field. If a field has 100 rows and is 327 yards (300 m) long, the\nestimator might walk staggered distances of 33 yards (30 m) along 10 randomly\nselected rows (for example, 0 to 33 yards [0 to 30 m] in row 9, 34 to 65 yards\n[31 to 60 m] in row 20; and so on). In each 33-yard (30-m) length, the\nestimator should randomly select 10 plants and estimate the damage on each\nplant\u2019s ear or head. Bird damage to corn can be estimated by measuring the length\nof damage on the ear (DeGrazio et al. 1969) or by visually estimating the\nper-cent loss of kernels (Woronecki et al. 1980) and converting to yield loss\nper acre (ha). Fruit loss can be estimated by counting the numbers of\nundamaged, pecked, and removed fruits per sampled branch (Tobin and Dolbeer\n1987). Sprouting rice removed by birds can be estimated by comparing plant\ndensity in exposed plots with that in adjacent plots with wire bird excloures\n(Otis et al. 1983). The seeded surface area of sunflower heads destroyed by\nbirds can be estimated with the aid of a clear plastic template (Dolbeer 1975).\n<\/p>\n\n\n

Losses of\nagricultural crops to birds can be estimated indirectly through avian\nbioenergetics. By estimating the number of birds of the depredating species\nfeeding in an area, the percent of the crop in the birds\u2019 diet, the caloric\nvalue of the crop, and the daily caloric requirements of the birds, one can\nproject the total biomass of crop removed by birds on a daily or seasonal basis\n(White et al. 1985, Weather-head et al. 1982). <\/p>\n\n\n

Damage Identification <\/h3>\n\n\n

Most bird damage\noccurs during day-light hours. Thus, observation is the best way to identify\nthe species causing damage. Presence of a bird species in a crop that is\nreceiving damage does not automatically prove the species guilty, however. For\nexample, large, conspicuous flocks of common grackles in sprouting winter wheat\nfields were found, after careful observation and examination of stomach\ncontents, to be eating corn residue from the previous crop. Smaller numbers of\nstarlings were removing the germinating wheat seeds (Dolbeer et al. 1979).\nBelow, the characteristics of damage for various groups of birds are described.\n<\/p>\n\n\n

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Gulls <\/h2>\n\n\n

Several gull species\nhave adapted to existing in proximity to people, taking advantage of landfills\nfor food. For example, the ring-billed gull population in the Great Lakes\nregion has been increasing at about 10% per year since the early 1970s\n(Blokpoel and Tessier 1984). Gulls are the most serious bird threat to flight\nsafety at airports (Solman 1981). They are increasingly causing nuisance\nproblems in urban areas by begging for food, defacing property, contaminating\nmunicipal water supplies, and nesting on roof-tops. In rural areas, gulls\nsometimes feed on fruit crops, consume fish at aquaculture facilities, eat duck\neggs and kill ducklings, and compete with threatened bird species for nest\nsites. <\/p>\n\n\n

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Blackbirds and Starlings <\/h2>\n\n\n

The term blackbird<\/em> loosely refers to a group of\nabout 10 species of North American birds, the most common of which are the\nred-winged blackbird, common grackle, and brown-headed cowbird. The starling, a\nEuropean species introduced to North America in the late 1800s, superficially\nresembles native blackbirds and often associates with them. Together,\nblackbirds and starlings constitute the most abundant group of birds in North\nAmerica, comprising a combined population of more than 1 billion (Dolbeer and\nStehn 1983). <\/p>\n\n\n

Blackbird damage to\nripening corn, sunflower, and rice can be serious (Dolbeer 1994). Much of this\ndamage is done in late summer during the milk or dough stage of seed\ndevelopment. The seed contents of corn are removed, leaving the pericarp or\nouter coat on the cob. Blackbird damage to sprouting rice in the spring can be\nimportant in localized areas. <\/p>\n\n\n

Starling\ndepredations at feedlots in winter can cause substantial losses (Glahn et al.\n1983, Besser et al. 1968). Although contamination of livestock feed by starling\nfeces is often a concern of farmers, a study indicated this contamination did\nnot interfere with food consumption or weight gain of cattle and pigs (Glahn\nand Stone 1984). Star-lings can be serious depredators in fruit crops such as\ncherries and grapes. <\/p>\n\n\n

Perhaps the greatest\nproblem caused by blackbirds and starlings is their propensity to gather\ntogether in large, nocturnal roosting congregations, especially in winter. The\nnoise, fecal accumulation, and general nuisance caused by millions of birds\nroosting together near human habitations can be significant (White et al.\n1985). Roosting birds near airports can create a safety hazard for aircraft.\nRoost sites, if used for several years, can become focal points for the fungus\nthat causes histoplasmosis. <\/p>\n\n\n

Pigeons and House Sparrows <\/h2>\n\n\n

Pigeons and house\nsparrows are urban and farmyard birds whose droppings deface and deteriorate\nbuildings. Around storage facilities they consume and contaminate grain.\nPigeons and sparrows may carry and spread various diseases to people, primarily\nthrough their droppings (Weber 1979). Droppings allowed to accumulate over\nseveral years are of particular concern because they may harbor spores of the\nfungus that causes histoplasmosis. House sparrows can damage small grain crops\nbut this is normally of economic concern only around agricultural experiment\nstations with small but valuable research plots (Royall 1969). Sparrows build\nbulky grass nests in buildings, drain spouts, and other sites where they can\ncause fire hazards or other problems. <\/p>\n\n\n

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Crows, Ravens, and Magpies <\/h2>\n\n\n

Crows, ravens, and\nmagpies are well-known predators of eggs and nestlings in other birds\u2019 nests.\nIn certain situations, these species kill newborn lambs or other livestock by\npecking their eyes (Larsen and Dietrich 1970). Magpies sometimes peck scabs on\nfreshly branded cattle. <\/p>\n\n\n

Crows occasionally\ndamage agricultural crops such as sprouting and ripening corn, apples, and\npecans. Most of this loss is localized and minor. Crow damage to apples can be\ndistinguished from damage by smaller birds by the deep (up to 2 inches [5 cm]),\ntri-angular peck holes (Tobin et al. 1989). trees in parks and cemeteries\nsome-times cause nuisance problems because of noise and feces. <\/p>\n\n\n

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Herons, Bitterns, and Cormorants <\/h2>\n\n\n

These species\nsometimes concentrate at fish-rearing facilities and cause substantial losses\n(Salmon and Conte 1981). Salmon smelts released in rivers in the northeastern\nUnited States have suffered heavy depredation by cormorants. In recent years,\ndouble-crested cormorants have caused serious losses at commercial fish ponds\nin the southern United States (Stickley and Andrews 1989). Nighttime observations\nare sometimes necessary to determine the depredating species because herons and\nbitterns will feed at night. <\/p>\n\n\n

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Hawks and Owls <\/h2>\n\n\n

The raptors most\noften implicated in predation problems with livestock (primarily poultry and\ngame farm fowl) are goshawks, red-tailed hawks, and great-horned owls\n(Hygnstrom and Craven 1994). Unlike mammalian predators, raptors usually kill\nonly one bird per day. Raptor kills usually have bloody puncture wounds in the\nback and breast. Owls often remove the head. Raptors generally pluck birds,\nleaving piles of feathers. Plucked feathers with small amounts of tissue clinging\nto their bases were pulled from a cold bird that had probably died from other\ncauses and was simply scavenged by the raptor. If the base of a plucked feather\nis smooth and clean, the bird was plucked soon after dying. Because raptors\nhave large territories and are not numerous in any one area, the removal of one\nor two individuals will generally solve a problem. <\/p>\n\n\n

Golden Eagles <\/h2>\n\n\n

Golden eagles\noccasionally kill live-stock, primarily lambs and kids on range. This predation\ncan be locally severe in the sheep-producing areas from New Mexico to Montana\n(Phillips and Blom 1988). <\/p>\n\n\n

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Close examination is\nneeded to identify an eagle kill. Eagles have three front toes opposing the\nhind toe, or hallux, on each foot. The front talons normally leave punctures\nabout 1 to 2 inches (2.5 to 5.0 cm) apart in a straight line or small \u201cV\u201d and\nthe wound from the hallux will be 4 to 6 inches (10 to 15 cm) from the middle\ntoe. In contrast, mammalian predators almost always leave four punctures or\nbruises from the canine teeth. Talon punctures are usually deeper than tooth\npunctures and there is seldom any crushing of tissue between the talon punctures.\nIf a puncture cannot be seen from the outside, skin the carcass to determine\nthe pattern of talon or tooth marks. Often a young lamb is killed with a single\npuncture from the hallux in the top of the skull and the three opposing talons\npuncturing the base of the skull or top of the neck (O\u2019Gara 1978, O\u2019Gara 1994).\n<\/p>\n\n\n

Woodpeckers <\/h2>\n\n\n

Woodpeckers at times\ncause damage to buildings with wood siding, especially cedar and redwood (Evans\net al. 1983). The birds peck holes to locate insects, store acorns, or establish\nnest sites. They also damage utility poles. Sapsuckers attack trees to feed on\nthe sap, bark tissues, and insects attracted to the sap. This feeding can\nsometimes kill the tree or degrade the quality of wood for commercial purposes\n(Ostry and Nicholls 1976). Woodpeckers occasionally annoy homeowners by\nknocking on metal rain gutters and stove pipes to proclaim their territories. <\/p>\n\n\n

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Ducks, Geese, and Sand hill Cranes <\/h2>\n\n\n

Damage by ducks and\ncranes to swathed or maturing small grain crops during the fall harvest is a\nserious localized problem in the northern Great Plains region (Knittle and\nPorter 1988). Damage occurs from direct consumption of grain and from\ntrampling, which dislodges kernels from heads. Losses from trampling may be at\nleast double the losses from consumption (Sugden and Goerzen 1979). <\/p>\n\n\n

Canada and snow\ngeese that graze on winter wheat and rye crops can reduce subsequent grain and\nvegetative yields (Kahl and Samson 1984, Conover 1988). Canada geese can also\ncause serious damage to sprouting soybeans in spring and to standing corn\nfields in the autumn. Canada geese have adapted to suburban environments in the\npast 20 years, creating nuisance problems around parks and golf courses through\ngrazing and defecation (Conover and Chasko 1985). <\/p>\n\n\n

Ungulates (Deer, Elk, Moose) <\/h2>\n\n\n

Damage Assessment <\/h3>\n\n\n

Ungulate damage to various agricultural, forestry, and\nornamental crops caused by feeding, trampling, and antler rubbing is an\nincreasing problem. Deer browsing in winter on buds of apple and other fruit\ntrees can reduce yields the following year (Austin and Urness 1989) or\nadversely alter the growth pattern of tree limbs (Harder 1970). Similar\nbrowsing on nursery plants and in Christmas tree plantations can reduce or\neliminate their market value (Scott and Townsend 1985). Browsing of hardwood\nsaplings and young fir trees in regenerating forests can reduce growth rates, misshape\ntrees, and even cause plantation failures (Crouch 1976, Tilghman 1989). <\/p>\n\n\n

Damage to trees caused by antler rubbing can be severe\n(Scott and Townsend 1985). Small trees (1\/2 to 1 inch [1.6 to 2.5 cm] in\ndiameter at 6 inches [15 cm] above ground) with smooth bark, such as green ash,\nplum, and cherry, were preferred for antler rubbing by white-tailed deer in an\nOhio nursery (Nielsen et al. 1982). <\/p>\n\n\n

Objective estimates of economic loss from ungulate browsing\nand rubbing in orchards, nurseries, and reforestation projects are difficult to\nobtain. Losses in yield or tree value may accumulate for many years after\ndamage occurs and vary with other stresses, including rodent damage, inflicted\non the plants. In Ohio, growers reported average losses to deer in 1983 of $82\nper acre ($204\/ha) for orchards, $89 per acre ($219\/ha) for Christmas tree\nplantings, and $108 per acre ($268\/ha) in nursery plantings (Scott and Townsend\n1985). Losses apparently are in the millions of dollars annually in some US\nstates (Black et al. 1979, Craven 1983b<\/em>, Connelly et al. 1987). <\/p>\n\n\n

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Deer also feed on various agricultural crops, especially\nyoung soybean plants and ripening ears of corn. Hygnstrom and Craven (1988)\nestimated a mean loss of 2,397 pounds of corn per acre (2,680 kg\/ha) for 51\nunprotected corn fields in Wisconsin. Yield reductions in soybean fields are\nmost severe when feeding occurs during the first week of sprouting (DeCalesta\nand Schwendeman 1978). Elk in some areas raid hay-stacks and cattle feedlots\n(Eadie 1954). <\/p>\n\n\n

Damage Identification <\/h3>\n\n\n

Ungulates do not have an upper set of incisors. Thus, twigs\nor plants nipped by these hoofed species do not show the neat, sharp-cut edge\nleft by most rodents and lagomorphs, but instead show a rough, shredded edge,\nand usually a square or ragged break. Pearce (1947) observed that deer in the\nNortheast seldom browse higher than 6 feet (1.8 m) from a standing position,\nbut are able to reach up to 8 feet (2.5 m) by rearing up on their hind legs.\nElk and moose browse to a height of about 10 feet (3 m). Deer seldom browse on\nbranches more than 1 inch <\/p>\n\n\n

(2.5 cm) in diameter. Moose and elk will gnaw the bark of\naspen trees. When male ungulates rub the velvet from their antlers, the\nscarring is generally confined to the trunk area up to 3 feet (1 m) high\n(Pearce 1947). <\/p>\n\n\n

Rodents and other Small Mammals <\/h2>\n\n\n

Damage Assessment <\/h3>\n\n\n

Rodents and other small mammals are seldom observed in the\nact of causing damage, and their damage is frequently difficult to measure.\nNonetheless, assessments of damage that have been made indicate rodents and\nnon-predatory small mammals cause tremendous annual losses of food and fiber in\nthe United States. Forest animal dam-age in Washington and Oregon was estimated\nto total $60 million annually to Douglas fir and ponderosa pine and the\npotential reduction in the total value of forest resources was estimated to be\n$1.83 billion (Black et al. 1979, Brodie et al. 1979). Although these figures\ninclude losses attributable to ungulates, rodents and hares are responsible for\nmuch of the damage. <\/p>\n\n\n

Miller (1987) surveyed forest managers and natural resource\nagencies in 16 southeastern states and estimated annual wildlife-caused losses,\nprimarily by beavers, to be $11.2 million on 70 million acres (28.4 million\nha). An additional $1.6 million was spent to control wildlife damage on this\nland. Arner and Dubose (1982) estimated that economic loss to beavers exceeded\n$4 billion over a 40-year period on 988,000 acres (400,000 ha) in the\nsouth-eastern United States. Annual loss in Mississippi to non-impounded timber\nwas estimated to be $215 million over a period of at least 10 years (Bullock\nand Arner 1985). <\/p>\n\n\n

Rats cause substantial losses to sugar-cane. Lefebvre et al.\n(1978) estimated annual losses to be about $6 million ($95 per acre, [$235\/ha])\nin one-third of the area producing sugarcane in Florida. Hawaiian losses were\nreported to be in excess of $20 million per year (Seubert 1984). Ferguson\n(1980) estimated that in 1978, voles caused losses that approached $50 million\nto apple growers in the eastern United States. Losses of forage on range lands to\nrodents, rabbits, and hares are also known to be extensive; however, accurate\nestimates of the monetary losses are difficult to obtain because of the nature\nof the damage and the wide area over which it occurs (Marsh 1985). <\/p>\n\n\n

Pearson and Forshey (1978) compared yields of apple trees\nvisibly damaged by voles to those not showing damage to determine the dollar\nlosses in gross return per tree. Richmond et al. (1987) determined reductions\nin growth, yield, and fruit size of apple trees dam-aged by pine vole\npopulations of known size maintained in enclosures around the trees. <\/p>\n\n\n

An index of rodent damage to sugar-cane was developed\nthrough sampling at harvest to determine the percent of stalks damaged\n(Lefebvre et al. 1978). Clark and Young (1986) established transects in corn\nfields and noted rodent damage to individual seedlings over a 10-day period.\nForage losses have been estimated by comparing production on areas with and\nwithout rodents (Turner 1969, Foster and Stubbendieck 1980, Luce et al. 1981).\nSauer (19k will gnaw the bark of\naspen trees. When male ungulates rub the velvet from their antlers, the\nscarring is generally confined to the trunk area up to 3 feet (1 m) high\n(Pearce 1947). <\/p>\n\n\n

Rodents and other Small Mammals <\/h2>\n\n\n

Damage Assessment <\/h3>\n\n\n

Rodents and other small mammals are seldom observed in the\nact of causing damage, and their damage is frequently difficult to measure.\nNonetheless, assessments of damage that have been made indicate rodents and\nnon-predatory small mammals cause tremendous annual losses of food and fiber in\nthe United States. Forest animal dam-age in Washington and Oregon was estimated\nto total $60 million annually to Douglas fir and ponderosa pine and the\npotential reduction in the total value of forest resources was estimated to be\n$1.83 billion (Black et al. 1979, Brodie et al. 1979). Although these figures\ninclude losses attributable to ungulates, rodents and hares are responsible for\nmuch of the damage. <\/p>\n\n\n

Miller (1987) surveyed forest managers and natural resource\nagencies in 16 southeastern states and estimated annual wildlife-caused losses,\nprimarily by beavers, to be $11.2 million on 70 million acres (28.4 million\nha). An additional $1.6 million was spent to control wildlife damage on this\nland. Arner and Dubose (1982) estimated that economic loss to beavers exceeded\n$4 billion over a 40-year period on 988,000 acres (400,000 ha) in the\nsouth-eastern United States. Annual loss in Mississippi to non-impounded timber\nwas estimated to be $215 million over a period of at least 10 years (Bullock\nand Arner 1985). <\/p>\n\n\n

Rats cause substantial losses to sugar-cane. Lefebvre et al.\n(1978) estimated annual losses to be about $6 million ($95 per acre, [$235\/ha])\nin one-third of the area producing sugarcane in Florida. Hawaiian losses were\nreported to be in excess of $20 million per year (Seubert 1984). Ferguson\n(1980) estimated that in 1978, voles caused losses that approached $50 million\nto apple growers in the eastern United States. Losses of forage on range lands to\nrodents, rabbits, and hares are also known to be extensive; however, accurate\nestimates of the monetary losses are difficult to obtain because of the nature\nof the damage and the wide area over which it occurs (Marsh 1985). <\/p>\n\n\n

Pearson and Forshey (1978) compared yields of apple trees\nvisibly damaged by voles to those not showing damage to determine the dollar\nlosses in gross return per tree. Richmond et al. (1987) determined reductions\nin growth, yield, and fruit size of apple trees dam-aged by pine vole\npopulations of known size maintained in enclosures around the trees. <\/p>\n\n\n

An index of rodent damage to sugar-cane was developed\nthrough sampling at harvest to determine the percent of stalks damaged\n(Lefebvre et al. 1978). Clark and Young (1986) established transects in corn\nfields and noted rodent damage to individual seedlings over a 10-day period.\nForage losses have been estimated by comparing production on areas with and\nwithout rodents (Turner 1969, Foster and Stubbendieck 1980, Luce et al. 1981).\nSauer (1977) used exclusion cylinders to determine losses of forage to ground\nsquirrels. Alsager (1977) described a method to determine for-age production\nreductions from pocket gopher damage. These methods are useful in evaluating\nefficacy of control techniques. However, loss estimates must be converted to accurate\nassessments of dollar loss to enable benefit-cost evaluation of control\nprograms. This conversion is difficult given the vast acreages involved and the\nvariability in rodent populations. <\/p>\n\n\n

In some situations (for example, timber flooded by beaver,\ngopher damage to conifer seedlings, vole damage to apple trees), failure to\ninitiate control may mean loss of the entire resource. Thus, potential loss in\nthese situations is equal to the cost of replacement of the resource. In other\nsituations, control may be necessitated irrespective of cost (for example, rats\nor mice in homes). <\/p>\n\n\n

These examples illustrate the complexity of damage\nsituations and the need for better damage assessment methods, an area of high\npriority for future research. Lack of methods for deter-mining damage levels\nhas been a serious impediment to the development of cost-effective control\nstrategies. <\/p>\n\n\n

Damage Identification <\/h3>\n\n\n

Most wild mammals are secretive and not easily observed;\nmany are nocturnal. Often the investigator must rely on various signs, such as\ntracks, trails, tooth marks, scats, or burrows to determine the species doing\nthe dam-age. Trapping may be necessary to make a positive identification of\nsmall rodents; frequently, more than one species is involved. <\/p>\n\n\n

Characteristics of the damage may also provide clues to the\nspecies involved. In orchards, for example, major stripping of roots is usually\ncaused by pine voles, whereas damage at the root collar or on the trunk up to\nthe extent of snow depth is most often caused by meadow voles. In sugar-cane,\nvarious species of rats gnaw stalks so that they are hollowed out between the\ninternodes but usually not completely severed. Rabbits, in contrast, usually\ngnaw through the stalks, leaving only the ring-shaped inter-nodes. <\/p>\n\n\n

Damage to plants can generally be grouped as follows: root damage\n\u2014 pocket gophers and pine voles; trunk debarking\u2014meadow voles, squirrels,\nporcupines, wood rats, rabbits, and mountain beavers; stem and branch\ncutting\u2014beavers, rabbits, meadow voles, mountain beavers, pocket gophers, wood\nrats, squirrels, and porcupines; needle clipping\u2014mice, squirrels, mountain\nbeavers, porcupines, and rabbits; debudding\u2014red squirrels and chipmunks. These\ncharacteristics can aid in identification of the species responsible, but\npositive identification should be made either by species-specific signs\n(tracks, hair, droppings) or by capture of individuals. <\/p>\n\n\n

Armadillos <\/h2>\n\n\n

The armadillo has extended its range eastward and northward\nfrom Texas and is now found in all Gulf Coast states and parts of New Mexico,\nOklahoma, Kansas, Arkansas, and Missouri (Humphrey 1974). Armadillos feed\nprimarily on invertebrates obtained by rooting in ground cover. When rooting\ntakes place in lawns, golf courses, or gardens, economic damage results. There\nis also concern about the impact of armadillos on forest floor communities\nwithin their expanded range (Carr 1982). <\/p>\n\n\n

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Armadillo burrows under orchard trees can cause root damage\nor excessive aeration (Marsh and Howard 1990). Nuisance problems result when\narmadillos burrow under structures. Armadillos carry the bacterium that causes\nleprosy in humans, but their importance in transmission of the disease to\nhumans has not been deter-mined (Davidson and Nettles 1988). <\/p>\n\n\n

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Bats <\/h2>\n\n\n

Bats, the only mammals capable of true flight, eat vast\nquantities of insects. Only a few of the 40 species of bats found in the United\nStates and Canada cause problems, primarily when they form roosts or maternity\ncolonies in human dwellings or structures. Those most commonly encountered in\npest situations are the little brown bat, big brown bat, Mexican free-tailed\nbat, pallid bat in the South-west, and Yuma myotis<\/em> in the West\n(Greenhall 1982, Frantz 1986). Species identification may be difficult but is\nimportant because several bat species are endangered and protected by state and\nfederal law. Control operators unfamiliar with bat identification are urged to\nseek professional help from wildlife agencies or universities (Frantz 1986). <\/p>\n\n\n

The presence of bats in a building is usually evidenced by\nnoise (squeaking, scratching) and by the presence and distinctive pungent odor\nof the accumulated fecal droppings and urine. Bat feces are readily\ndistinguished from those of rodents by odor, insect con-tent, and the ease with\nwhich they are crushed (Greenhall 1982). <\/p>\n\n\n

Many people are fearful of bats and panic in their presence.\nBats occasion-ally contract rabies, and although few human deaths have resulted\nfrom bat-transmitted rabies (Greenhall 1982), contact with a rabid bat or a\nbite by a bat that escapes requires post exposure treatment of people and pets\nwithout current vaccinations (Frantz 1986). The fungal causative organism of\nhistoplasmosis, a respiratory disease of humans, can develop where bat colonies\nare allowed to persist and guano deposits accumulate. Bats roosting near\nairports may be hazardous to air-craft (Kincaid 1975). <\/p>\n\n\n

Beavers <\/h2>\n\n\n

Beaver damage is easily identified by the distinctive\ncone-shaped tree stumps resulting from their gnawing, and often by the presence\nof their dams and lodges. The latter might not be present, however, in ponds or\nreservoirs, or along swift mountain streams, where they burrow into banks.\nUsually, when beavers are active in an area; green sticks with the bark freshly\npeeled off may be found. <\/p>\n\n\n

Damage caused by beavers results from feeding behavior (tree\ncutting) and their efforts to control water levels (dam building). Tree cutting\nin certain situations results in selective elimination of preferred tree\nspecies, such as aspen and cottonwood, from the vicinity (Beier and Barrett\n1987). Loss of timber and crops from flooding is of much greater importance,\nhowever, especially in the southeastern United States where beaver populations\nhave increased dramatically as a result of a decline in trapping due to low\npelt prices (Woodward 1985). Beavers often use sticks to plug road culverts or\nwater-control structures in ponds and reservoirs. Additionally, beavers can\ncause extensive damage to levees and human-made dams by their burrowing. <\/p>\n\n\n

Beavers are susceptible to infection by protozoan parasites\n(Giardia<\/em> spp.) that can cause gastroenteritis and diarrhea in humans.\nTransmission to humans can be prevented by use of proper water treatment\nmeasures (Davidson and Nettles 1988). <\/p>\n\n\n

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Chipmunks <\/h2>\n\n\n

Occasionally, chipmunks damage grain fields, garden seeds,\nflower bulbs, and plants through burrowing and feeding. They infrequently\ndestroy eggs and nestling birds (Eadie 1954). They can establish residence in\nor under human dwellings. Chipmunks cause reforestation problems by consuming\nseeds, seedlings, and the terminal buds of older plants, and by caching seeds,\noften in large quantities (Marsh and Howard 1990). In parts of the western\nUnited States, chipmunks are a potential reservoir for plague and are\ncontrolled in campgrounds (Marsh and Howard 1990). Chipmunks are easily\nobserved due to their diurnal activity; their presence can also be determined\nby trapping. <\/p>\n\n\n

Cotton Rats <\/h2>\n\n\n

The hispid cotton rat, a common species in the southern\nUnited States and in Mexico, is the species of cotton rat most often causing\ndamage. Two other species have localized occurrences in Arizona and New Mexico.\nCotton rats are primarily herbivorous, but they also prey on eggs and young of\nground nesting birds (Hawthorne 1994). They undergo major population\nfluctuations. Most damage is a result of feeding in agricultural crops,\nespecially melons and sugarcane. <\/p>\n\n\n

Cotton rats are active day and night and, when abundant, are\noften ob-served. Their presence is also indicated by well developed runways\nthrough dense vegetation and the presence of grass cuttings 2 to 3 inches (5 to\n8 cm) in length placed in piles. Pale greenish-yellow droppings, about 1\/2 inch\n(0.9 cm) long and 1\/4 inch (0.5 cm) wide, are sometimes present in the runway.\nCotton rat sign is similar to that of voles but droppings, runways, and\nclippings of the cotton rat are usually larger (Hawthorne 1994). Cotton rats\nare often one of several rodent species causing damage in crops. <\/p>\n\n\n

Peromyscus<\/em> (Deer Mice, White-footed Mice) <\/h2>\n\n\n

The genus Peromyscus <\/em>is large, and one or more\nspecies is found in all parts of North America. These mice are nocturnal and\nactive all year. Peromyscus <\/em>populations may show large fluctuations.\nThese mice are the most important seed predators in the Pacific Northwest,\ncausing extensive damage in reforestation efforts (Sullivan 1978). Effects on\nreforestation have caused a shift to the use of hand-planted seed-lings in many\nareas. Peromyscus<\/em> also can cause significant losses to corn seedlings in\nconservation tillage systems but this damage may be offset by their consumption\nof harmful insects and weed seeds (Johnson 1986, Clark and Young 1986). Peromyscus<\/em>\nmay invade homes where they eat stored food and damage upholstered furniture or\nother materials shredded for use in nest building. They recently have been\nimplicated in the transmission of an often fatal hantavirus to humans.\nInfections may occur through contact with mouse urine, feces, or saliva.\nTrapping with snap or live traps is the best method to determine the species\npresent. <\/p>\n\n\n

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Ground Squirrels <\/h2>\n\n\n

Ground squirrels (genus Spermophilus<\/em>), are important\npest species in north central and western North America, causing serious losses\nof tree seeds and emergent seedlings. A careful search of an area showing\ndamage will reveal opened seed hulls and caches. Ground squirrels can inflict\nserious damage to pastures, rangelands, grain fields, vegetable gardens, and\nfruit or nut crops. Their burrows can cause collapse of irrigation levees,\nincrease erosion, and result in damage to farm machinery. They are also an\nimportant predator of waterfowl eggs in the prairie pothole region (Sargeant\nand Arnold 1984). They carry several diseases transmissible to humans, including\nplague; in plague endemic areas, ground squirrel control should be combined\nwith ectoparasite control (Marsh and Howard 1990). <\/p>\n\n\n

Ground squirrels are diurnal and easily observed (Marsh 1985). They hibernate and estivate, and have major dietary shifts during the year (Marsh 1985, 1986). Effective control strategies must consider these factors.<\/p>\n\n\n

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Kangaroo Rats <\/h2>\n\n\n

Kangaroo rats are competitors of live-stock on arid western\nrangelands (Marsh 1985) when present in high populations, especially during\ndrought. They can also retard recovery of overgrazed rangelands when cattle are\nremoved (Howard 1994) and spread undesirable shrub species by caching of seeds\n(Reynolds and Glendening 1949, Marsh 1985). Kangaroo rats cause significant damage\nto alfalfa and corn on irrigated sandy soils by consuming newly planted seeds\nand clipping off seedlings (Howard 1994). Sorghum, other grains, and garden\ncrops can also be damaged in local areas. <\/p>\n\n\n

Several species of kangaroo rats are endangered. Kangaroo\nrats are nocturnal, but their burrow systems, with aboveground mounds and\ninterconnecting runways, are readily observed. Snap trap surveys can identify\nthe species present, provided the damage area is not within the range of one of\nthe species listed as endangered. <\/p>\n\n\n

Marmots <\/h2>\n\n\n

Marmots (woodchucks), like ground squirrels, can cause\ndamage to many crops; forage production may be markedly reduced by marmot\nfeeding and trampling (Marsh 1985). They damage fruit trees and ornamental\nshrubs by gnawing or scratching woody vegetation (Bollengier 1994). Their\nburrows, often located along field edges, can cause damage to farm machinery\nand injure livestock; when located along irrigation ditches they can cause loss\nof water. In suburban areas, burrows located under buildings or in landscaped\nareas cause problems (Marsh and Howard 1990). The presence of woodchucks is\neasily determined by direct observation of animals and burrows. During periods\nof forage growth, vegetation around burrows is noticeably shorter than in surrounding\nareas. Occupied burrows can be identified in spring by the presence of dirt\npellets ranging from marble to fist size. <\/p>\n\n\n

Voles <\/h2>\n\n\n

Voles (genus Microtus<\/em>), also called meadow mice,\nfield mice, and pine mice, cause extensive damage to forests, orchards, and\nornamentals by gnawing bark and roots (Pearson and Forshey 1978, Byers 1984,\nPauls 1986, Sullivan et al. 1987, O\u2019Brien 1994). Tree or shrub damage usually\noccurs under snow or dense vegetation; the bark is gnawed from small trees near\nthe root collar and up the trunk as far as the snow extends. Voles gnaw through\nsmall trees or shoots up to about 1\/4 inch (0.6 cm) in diameter. Some species\n(for example, pine vole) also cause extensive damage to root systems; this\ndamage may not be detected until spring when it is reflected in the condition\nof new foliage. Voles can also damage field and garden crops; when vole\npopulations are high, these losses can be catastrophic (Clark 1984, Marsh\n1985). Voles are carriers of plague and tularemia. <\/p>\n\n\n

Vole populations are subject to large, rapid fluctuations. The presence of voles is most easily determined by searching for their runways and bur-row systems. In orchards these can be found by pulling the grass and other debris from the bases of trees to expose the runways. Burrows of pine voles are usually subterranean. Gnawing on the trunks and roots of trees is usually less uniform than that of other rodents. Tooth marks can be at all angles, even on small branches, and may vary from light scratches to channels 1\/10 inch (0.3 cm) wide, 1\/12 inch (0.2 cm) deep, and 1\/2 inch (1.3 cm) long. In hay crops, runways with numerous burrow openings, clipped vegetation, and feces, can be located in dense vegetation. <\/p>\n\n\n

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Moles<\/a> <\/h2>\n\n\n

Moles feed primarily on soil invertebrates, especially earthworms\nand grubs (beetle larvae). About 20% of their food is plant material, which may\ninclude garden vegetables and small grains (Silver and Moore 1941). Voles and\nmice use the burrows of moles and can be responsible for some dam-age\nattributed to moles (Henderson 1994). Burrowing by moles may reduce production\nof forage crops by undermining and smothering vegetation, and by exposing root\nsystems to drying. Their surface burrows can also plug harvesting machinery and\ncontaminate hay and silage (Wick and Landforce 1962). Moles can damage lawns\nand golf greens extensively through burrowing. <\/p>\n\n\n

The presence of moles can usually be detected by the mounds\nof soil thrown up from extensive tunnels dug in search of food and by the\nraised soil of surface burrows. Mole hills can be distinguished from pocket\ngopher mounds by their more rounded con-tour and the lack of a burrow entrance\nor soil plug (Eadie 1954). <\/p>\n\n\n

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Mountain Beavers<\/a> <\/h2>\n\n\n

Mountain beavers cause serious economic loss by burrowing\nthrough and feeding on garden vegetables, berry plants, and young trees. They\nuse drainage ditches for burrow sites, and their burrows may undermine\nroad-ways. <\/p>\n\n\n

Mountain beavers are a major factor limiting reforestation\nin the Pacific Northwest (Borrecco and Anderson 1980, Evans 1987a<\/em>).\nPlantations are most susceptible to damage for 4 years after planting and when\npre-commercially thinned at about 12 to 15 years (Evans 1987a<\/em>). Mountain\nbeavers clip seedlings and gnaw saplings and the stems and bark of larger\ntrees. <\/p>\n\n\n

Mountain beavers normally clip seed-lings through at a 45o<\/sup> angle. On small seedlings this clipping may be\ndifficult to distinguish from rabbit damage; however, rabbits seldom clip stems\nlarger than 1\/4 inch (0.6 cm) in diameter or 20 inches (50 cm) above ground level,\nwhereas mountain beavers often cut stems larger than 1\/2 inch (1.3 cm) in\ndiameter and up to 9 feet (3 m) above ground (Lawrence et al. 1961). Mountain\nbeavers leave branch stubs, cut at a 45o<\/sup> angle, protruding from the main stem. The bark\nof the main stem shows horizontal tooth marks and vertical claw marks (Packham\n1970). Run-ways and burrows are present in or near the damaged area. <\/p>\n\n\n

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Muskrats<\/a> <\/h2>\n\n\n

Muskrats most often cause problems where people have created\nor manipulated wetlands or where wetlands border agricultural crops. The most\nserious damage results from burrows in pond dams, levees, and irrigation\ncanals. The burrow entrance is below water level and penetrates the embankment\nat an upward angle to allow for a room above the water level. Damage is\nincreased when the water level rises and the burrow is extended higher to\nprovide a dry chamber, thereby increasing chances of wash-outs and cave-ins. At\ntimes, muskrats cause severe damage to grain, such as rice, and to garden crops\ngrowing near water. Muskrats are primarily vegetarians, but they will feed on\naquatic animals where vegetation is limited (Miller 1994). <\/p>\n\n\n

Muskrats commonly construct cone-shaped houses projecting 6\ninches to 3 feet (15 to 90 cm) above the water surface. Muskrat presence is\nindicated by houses and burrow entrances. Under-water runs can be observed when\nthe water is clear or after a winter draw down of ponds or reservoirs (Miller\n1994). <\/p>\n\n\n

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Nutria<\/a> <\/h2>\n\n\n

Nutria are semiaquatic, herbivorous mammals that feed on\naquatic plants, roots, seeds, and crops grown close to waterways. The greatest\nlosses from this introduced rodent are to sugar-cane and rice, especially in\nfields adjacent to Gulf Coast marshes (LeBlanc 1994). Nutria may severely\nimpede cypress regeneration (Conner and Toliver 1987). They also damage wooden\nstructures and floating marinas. <\/p>\n\n\n

Nutria presence is evidenced by tracks, droppings, and\ntrails to and from the damage area. Nutria also may be observed in the damage\narea. <\/p>\n\n\n

Pocket Gophers<\/a> <\/h2>\n\n\n

Pocket gophers cause substantial dam-age to agricultural\ncrops, lawns, range-land, and tree plantings. Gophers feed primarily on the underground\nportions of plants and trees. Damage often is undetected until a tree shows\nabove-ground signs of stress; by then damage is frequently lethal (Cummings and\nMarsh 1978). Pocket gophers may also damage plastic irrigation lines on\nagricultural lands as well as underground pipes, cables, and electric wires. <\/p>\n\n\n

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On rangeland, soil disturbance and mound building by pocket\ngophers result in increased plant diversity and a replacement of perennial by\nannual grasses (McDonough 1974, Foster and Stubbendieck 1980, Marsh 1985). They\ncan greatly reduce the carrying capacity of rangeland for livestock. They can\nbe a serious pest in alfalfa by feeding on the leaves, stems, and roots (Marsh\n1985). Gopher mounds can cause equipment breakage and increased wear on haying\nmachinery. Gopher tunnels result in water loss in irrigated areas (Case and\nJasch 1994). <\/p>\n\n\n

Pocket gophers are a major impediment to reforestation in\nthe western United States (Crouch 1986). During winter pocket gophers often\nforage above ground by tunneling in the snow. Coniferous trees have been found\ndebarked to a height of 12 feet (3.5 m) by pocket gophers working under the snow\n(Capp 1976). Gophers also fill some of the snow tunnels with soil, thus forming\nlong tubular \u201ccasts\u201d that remain after the snow melts. <\/p>\n\n\n

Pocket gopher presence is easily deter-mined by fan-shaped\nsoil mounds in contrast to the conical mounds of moles. Burrow entrances are\nusually plugged. Aboveground debarking injuries caused by pocket gophers show\nsmall tooth marks, differing from the distinct broader grooves left by\nporcupines, and the finely gnawed surface caused by meadow voles. Gophers will\nat times pull saplings and vegetation into the burrow. <\/p>\n\n\n

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Porcupines<\/a> <\/h2>\n\n\n

Porcupines are usually nocturnal and are active all year.\nDuring summer, porcupines often feed on succulent plants, including garden and\ntruck crops in open meadows, fields, and along the banks of streams and lakes.\nGreatest damage is caused in winter when porcupines feed on the inner bark of\ntrees (Marsh and Howard 1990). Girdling in the upper trunk of trees often\nresults in dead tops (Evans 1987b<\/em>). Basal girdling may occur on\nseedlings. Porcupines are attracted to anything containing perspiration salt:\nsaddles, harnesses, belts, and tool handles. <\/p>\n\n\n

Porcupine damage can be identified by broad incisor marks on\nthe exposed sapwood. Abundant oblong droppings about 1 inch (2.5 cm) long can\nbe found under freshly damaged trees. Clipped twigs and tracks may also be\nfound on snow. Top girdling in pine results in trees with a characteristic\nbrushy crown. <\/p>\n\n\n

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Prairie Dogs<\/a> <\/h2>\n\n\n

Prairie dogs were widespread on the Great Plains throughout\nthe 1800s and reached peak numbers around 1900 after reduction of natural\npredators and establishment of cattle grazing. By 1921 the area occupied by\nprairie dogs was estimated to be 99 million acres (40 million ha). By 1971,\nfollowing intensive control efforts, only 1.5 mil-lion acres (0.6 million ha)\nwere occupied. Populations have been expanding in recent years, commensurate\nwith reduced control efforts (Fagerstone 1981). <\/p>\n\n\n

Prairie dogs damage rangelands and pastures by clipping\nvegetation for food and nesting material and by clearing cover from the\nvicinity of bur-rows (Hygnstrom and Virchow Gophers will\nat times pull saplings and vegetation into the burrow. <\/p>\n\n\n

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Porcupines<\/a> <\/h2>\n\n\n

Porcupines are usually nocturnal and are active all year.\nDuring summer, porcupines often feed on succulent plants, including garden and\ntruck crops in open meadows, fields, and along the banks of streams and lakes.\nGreatest damage is caused in winter when porcupines feed on the inner bark of\ntrees (Marsh and Howard 1990). Girdling in the upper trunk of trees often\nresults in dead tops (Evans 1987b<\/em>). Basal girdling may occur on\nseedlings. Porcupines are attracted to anything containing perspiration salt:\nsaddles, harnesses, belts, and tool handles. <\/p>\n\n\n

Porcupine damage can be identified by broad incisor marks on\nthe exposed sapwood. Abundant oblong droppings about 1 inch (2.5 cm) long can\nbe found under freshly damaged trees. Clipped twigs and tracks may also be\nfound on snow. Top girdling in pine results in trees with a characteristic\nbrushy crown. <\/p>\n\n\n

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Prairie Dogs<\/a> <\/h2>\n\n\n

Prairie dogs were widespread on the Great Plains throughout\nthe 1800s and reached peak numbers around 1900 after reduction of natural\npredators and establishment of cattle grazing. By 1921 the area occupied by\nprairie dogs was estimated to be 99 million acres (40 million ha). By 1971,\nfollowing intensive control efforts, only 1.5 mil-lion acres (0.6 million ha)\nwere occupied. Populations have been expanding in recent years, commensurate\nwith reduced control efforts (Fagerstone 1981). <\/p>\n\n\n

Prairie dogs damage rangelands and pastures by clipping\nvegetation for food and nesting material and by clearing cover from the\nvicinity of bur-rows (Hygnstrom and Virchow 1994). This activity not only\nreduces available forage, but can alter species composition of the vegetation\nin favor of forbs. <\/p>\n\n\n

Competition with cattle does not always exist, however, and\nin some situations beneficial effects of prairie dogs offset competition. Therefore,\neach conflict situation should be evaluated individually (Fagerstone 1981). <\/p>\n\n\n

Crops planted near prairie dog colonies can receive serious\ndamage from feeding and trampling. Also, damage to irrigation systems is\ncommon, and badgers digging for these rodents cause even greater damage. The\nbur-rows and mounds created by prairie dogs can increase soil erosion, cause\ndrainage of irrigation water, and result in damage to farm implements. Prairie\ndogs also serve as a reservoir for plague (Hygnstrom and Virchow 1994). <\/p>\n\n\n

Prairie dog colonies provide habitat for other species, such\nas the endangered black-footed ferret. All lethal control should be preceded by\na careful survey to ensure that ferrets are not present. The Utah prairie dog\nis a threatened species and should not be controlled. <\/p>\n\n\n

Prairie dog colonies are easily identified by the conical\nmounds around burrow entrances and by the presence of the easily observed\nanimals. <\/p>\n\n\n

Rabbits and Hares<\/a> <\/h2>\n\n\n

Rabbits and hares can damage or completely destroy tree\nplantings, gardens, ornamentals, agricultural crops, and rehabilitated\nrangeland. In winter, they strip bark from and debud fruit trees, conifers, and\nother trees and shrubs (Craven 1994). <\/p>\n\n\n

Rabbits are known vectors of tularemia, which is\ntransmissible to humans, and they may carry larvated eggs of several as carid\nroundworms that can produce disease if accidentally ingested (uncooked) by\nhumans (Davidson and Nettles 1988). <\/p>\n\n\n

Jackrabbits also damage orchards, gar-dens, ornamentals, and\nsome agricultural crops, especially in areas adjacent to rangeland, and most\nfrequently when natural vegetation is dry (Knight 1993). Jackrabbit populations\nshow large fluctuations, and, at times of high density, damage to rangeland\nvegetation and competition with livestock can be severe. <\/p>\n\n\n

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Trees clipped by rabbits and hares have a clean oblique\nknifelike cut on the stem. Rabbits and hares usually clip stems 1\/4 inch (0.6\ncm) in diameter or less at a height not more than 20 inches (50 cm) above the\nground (Lawrence et al. 1961). Repeated clip-ping will deform seedlings.\nRabbits and hares can often be observed at damage sites along with their\ntracks, trails, and droppings. <\/p>\n\n\n

Tree Squirrels<\/a> <\/h2>\n\n\n

Tree squirrels may be divided into three groups: large tree squirrels\n(gray, fox, and tassel-eared), pine squirrels (red and Douglas), and flying\nsquirrels (northern and southern) (Jackson 1994). Squirrels eat plants and\nfruit, dig up newly planted bulbs and seeds, strip bark and leaves from trees\nand shrubs, invade homes, and consume bird eggs (Jackson 1994, Hadidian et al.\n1987). They cause problems by shorting out transformers and gnaw-ing on power\nand telephone lines (Marsh and Howard 1990, Hamilton et al. 1987). <\/p>\n\n\n

Squirrels can often be observed at the damage site. Damage\nto conifer seed is indicated by green, unopened cones scattered on the ground\nunder mature trees and by the accumulated cone scales and \u201ccores\u201d at feeding\nstations. Bark stripping can be observed in trees and bark fragments are often\nfound on the ground, as are the tips of twigs and small branches. <\/p>\n\n\n

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Wood Rats<\/a> <\/h2>\n\n\n

Wood rats, also called pack rats, brush rats, or trade rats,\nare attracted to food supplies left in buildings and will remove small objects\nsuch as spoons, forks, knives, and other items, some-times leaving sticks or\nother objects \u201cin trade.\u201d They often construct conspicuous stick houses in\ncabins, abandoned vehicles, or in the upper branches of trees (Marsh and Howard\n1990, Salmon and Gorenzel 1994). They will shred mattresses and upholstery. <\/p>\n\n\n

Wood rats are agile climbers and consume fruits, seeds, and\ngreen foliage of herbaceous and woody plants (Lawrence et al. 1961). They strip\nand finely shred patches of bark from conifers and fruit trees to line nest\nchambers (Hooven 1959). They will also clip small branches. Their damage may be\nconfused with that of tree squirrels and porcupines; however, wood rats leave a\nrelatively smooth surface with a few scattered tooth marks, and tend to litter\nthe ground beneath the tree less than tree squirrels. <\/p>\n\n\n

Several subspecies of wood rats are endangered. Local\nregulations should be checked before control efforts are undertaken. <\/p>\n\n\n

Commensal Rodents<\/a> <\/h2>\n\n\n

The three species of commensal rodents (those that live\nprimarily around human habitation) are Norway rats, roof (black) rats, and\nhouse mice. These omnivorous rodents consume millions of bushels of grain each\nyear in the field, on the farm, in the elevator, mill, store, and home, and in\ntransit. They also waste many more millions of bushels by contamination. These\nrodents typically drop 25 to 150 pellets and void 1\/3 to 2\/3 ounce (10 to 20\nml) of urine every 24 hours and constantly shed fine hairs. <\/p>\n\n\n

Rats cause extensive damage to sugar-cane in Hawaii and\nFlorida, and roof rats are serious pests in Hawaiian macadamia nut plantations.\nThese rodents will feed on poultry chicks and occasionally even attack adult\npoultry, wild birds, newborn pigs, lambs, and calves. Health departments\nannually report hundreds of human babies bit-ten by rats. Many viral and\nbacterial diseases are transmitted to humans by rodent feces and urine that\ncontaminate food and water (Weber 1982). <\/p>\n\n\n

Gnawing by rodents causes consider-able property damage.\nFires are some-times started when rats and mice gnaw the insulation of electric\nwiring. They will also use materials such as oily rags and matches for building\nnests, which can result in fires by spontaneous combustion. Extensive damage to\nfoundations and concrete slabs is sometimes done when Norway rats burrow under\nbuildings. Burrows into dikes and outdoor embankments cause erosion. <\/p>\n\n\n

Signs of commensal rodents are gnawing, droppings, tracks,\nburrows, and darkened or smeared areas along walls where they travel. Reviews\nof problems caused by these species and methods of control are provided by Meehan\n(1984), Jackson (1987), Baker et al. (1993), Marsh (1994), and Timm (1994). <\/p>\n\n\n

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Carnivores and other Mammalian Predators<\/a> <\/h2>\n\n\n

Damage Assessment<\/a> <\/h3>\n\n\n

Mammalian predators have always been a concern to livestock\nproducers. Wade (1982) estimated that the direct loss of sheep and goats to\ncoyotes in the United States ranged from $75 mil-lion to $150 million annually.\nPearson (1986), using a summary of other studies and surveys, estimated the\nloss of sheep, lambs, and goats to predators (primarily coyotes) to be $68,160,000\nin the 17 western states in 1984. Terrill (1988), using data from all 50\nstates, reported that annual losses of sheep and lambs to coyotes and other\npredators ranged from $69 million to $83 million in 1985 to 1987. In 1990,\n490,000 sheep and lambs valued at $21.7 mil-lion and 129,400 goats valued at\n$5.6 million were lost to predators in the United States (NASS 1991). In 1991,\nthe National Agricultural Statistics Service estimated that predators killed\n106,000 cattle and calves in the United States, valued at $41.5 million (NASS\n1992). Losses of poultry to predators, although not well documented, are also\nthought to be substantial. <\/p>\n\n\n

Mammalian predators, especially red foxes, striped skunks,\nraccoons, and mink, seriously impact waterfowl nesting success in small wetland\nareas sur-rounded by agricultural lands. A study in North Dakota indicated nesting\nsuccess of only 8% for mallards on such wetlands, half of what was needed to\nsustain the population (Cowardin et al. 1985). The red fox is apparently the\nmost serious waterfowl predator because it is adept at catching nesting hens as\nwell as destroying eggs (Sargeant et al. 1984). <\/p>\n\n\n

Damage Identification<\/a> <\/h3>\n\n\n

Predation is rarely observed; therefore, the accurate assessment\nof losses to specific predators often requires careful investigative work. The\nfirst action in determining the cause of death of an animal is to check for\nsigns on the animal and around the kill site. Size and location of tooth marks\nwill often indicate the species causing predation. Extensive bleeding usually\nis characteristic of predation. Where external bleeding is not apparent, the\nhide can be removed from the carcass, particularly around the neck, throat, and\nhead, and the area checked for tooth holes, subcutaneous hemorrhage, and tissue\ndamage. Hemorrhage occurs only if skin and tissue damage occurs while the\nanimal is alive. Animals that die from causes other than predation normally do\nnot show external or subcutaneous bleeding, although bloody fluids may be lost\nfrom body openings (Bowns 1976). Animal losses are easiest to evaluate if\nexamination is conducted when the carcass is still fresh (Wade and Bowns 1982).\n<\/p>\n\n\n

Animals may not always be killed by a throat attack, but may\nbe pulled down from the side or rear. Blood is often on the sides, hind legs,\nand tail areas. Calves can have their tails chewed off and the nose may have\ntooth marks or be completely chewed by the predator when the tongue is eaten\n(Bowns 1976). <\/p>\n\n\n

Tracks and droppings alone are not proof of depredation or\nof the species responsible. They are evidence that a particular predator is in\nthe area and, when combined with other characteristics of depredation, can help\ndeter-mine what species is causing the problem. <\/p>\n\n\n

\"\"<\/figure>\n\n\n

Badgers<\/a> <\/h3>\n\n\n

Badgers eat primarily rodents such as mice, prairie dogs,\npocket gophers, and ground squirrels. They will also prey on rabbits,\nespecially the young. Badgers destroy nests of ground-nesting birds and\noccasionally kill small lambs and poultry, parts of which they sometimes bury\nin holes resembling their dens. Dens in crop fields may slow harvesting or\ncause damage to machinery, and the digging can damage earthen dams or dikes\n(Lindzey 1994). <\/p>\n\n\n

Badgers usually eat all of a prairie dog except the head and\nfur along the back. This characteristic probably holds true for most of the larger\nrodents they eat; however, signs of digging near prey remains are the best\nevidence of badgers. Badger tracks often appear similar to coyote tracks but on\nclose examination they are distinctively \u201cpigeon-toed\u201d with impressions from\nthe long toenails apparent in most situations. <\/p>\n\n\n

\"\"<\/figure>\n\n\n

Bears<\/a> <\/h3>\n\n\n

Black and grizzly bears prey on live-stock. Black bears\nusually kill by biting the neck or by slapping the victim. Torn, mauled, and mutilated\ncarcasses are characteristic of bear attacks. Often, the bear will eat the\nudders of female prey, possibly to obtain milk. The victim usually is opened\nventrally and the heart and liver are consumed (Bowns and Wade 1980). The intestines\nare often spread out around the kill site, and the animal may be partially\nskinned while the carcass is fed upon. Smaller livestock such as sheep and\ngoats may be consumed almost entirely, and only the rumen, skin, and large\nbones left. Feces are generally found within the kill area, and a bed-ding site\nis often found nearby. Bears use their feet while feeding so they do not slide\nthe prey around as do coyotes. If the kill is made in the open, it may be moved\nto a more secluded spot. <\/p>\n\n\n

The grizzly has a feeding and killing pattern similar to\nthat of the black bear. Murie (1948) found that most cattle are killed by a\nbite through the back of the neck. Large prey often have claw marks on the\nflanks or hams. The prey\u2019s back is sometimes broken in front of the hips where\nthe bear simply crushed it down. Young calves are occasionally bitten through\nthe forehead. <\/p>\n\n\n

The presence of bears has stampeded range sheep, resulting\nin death from suffocation or from falls over cliffs. A marauding bear searching\nfor food may also play havoc with garbage cans, cabins, camp sites, and\napiaries (Maehr 1983). <\/p>\n\n\n

Black bear damage to trees can be recognized by the large\nvertical incisor and claw marks on the sapwood and ragged strips of hanging\nbark. Pole-size trees to small saw timber are preferred. Most bark damage\noccurs during May, June, and July (Packham 1970). After the bark is pulled\naway, bears will scrape off the cambium layer of the tree with their incisor\nteeth, leaving vertical tooth marks (Murie 1954). <\/p>\n\n\n

The bear track resembles that of a human, but has\ndistinctive claw marks. The little inside toes often leave no marks in dust or\nshallow mud so the print appears to be four-toed (Murie 1954). <\/p>\n\n\n

\"\"<\/figure>\n\n\n

Bobcats and Lynx<\/a> <\/h3>\n\n\n

These related species occasionally prey on sheep, goats,\ndeer, and pronghorns; however, they more commonly kill smaller animals such as\nporcupines, poultry, rabbits, rodents, birds, and house cats. Bobcats\ncharacteristically kill adult deer by leaping on their back or shoulders,\nusually when the victim is lying down, and biting them on the trachea. The\njugular vein may be punctured, but the victims usually die of suffocation and\nshock. Bowns (1976) reported that a lamb killed by a bobcat had hemorrhages\nproduced by claws on both sides of the carcass, indicating that the bobcat had\nheld the lamb with its claws while biting the neck. Small fawns, lambs, and\nother small prey are often killed by a bite through the top of the neck or head\n(Young 1958). The hindquarters of deer or sheep are usually preferred by\nbobcats, although the shoulder and neck region or the flank are sometimes eaten\nfirst. The rumen is often untouched. Poultry are usually killed by biting the\nhead and neck (Young 1958); the heads are usually eaten. Also, both species\nreportedly prey on bird eggs. <\/p>\n\n\n

Bobcat and lynx droppings are similar; in areas inhabited by\nboth species, the tracks will help determine the responsible animal. The lynx\nhas larger feet with much more hair and the toes tend to spread more than they\ndo on the more compact bobcat tracks. <\/p>\n\n\n

Feline predators usually attempt to cover their kills with\nlitter (Cook et al. 1971). Bobcats reach out 12 to 14 inches (30 to 35 cm) in\nscratching litter, com-pared to a 35-inch (90-cm) reach of a mountain lion\n(Young 1958). The distance between the canine teeth marks will also help\ndistinguish a lion kill from that of a bobcat\u20141 1\/2 inches (3.8 cm) for a lion\nversus 3\/4 to 1 inch (1.9 to 2.5 cm) for a bobcat (Wade and Bowns 1982). <\/p>\n\n\n

\"\"<\/figure>\n\n\n

Coyotes, Wolves, and Dogs<\/a> <\/h3>\n\n\n

These predators prey on animals ranging from big game and livestock\nto rodents, wild birds, and poultry. Coyotes are the most common and most\nserious predator of livestock in the western United States (Wade and Bowns\n1982) and are rapidly becoming a problem throughout the east. <\/p>\n\n\n

Coyotes normally kill livestock with a bite in the throat,\nbut they infrequently pull the animal down by attacking the side, hindquarters,\nand udder. The rumen and intestines may be removed and dragged away from the\ncarcass. On small lambs, the upper canine teeth may penetrate the top of the\nneck or the skull. Calf predation by coyotes is most common when calves are\nyoung. Calves that are attacked, but not killed, exhibit wounds in the flank,\nhindquarters, or front shoulders; often their tails are chewed off near the\ntop. Deer carcasses are frequently completely dismembered and eaten (Bowns\n1976). <\/p>\n\n\n

Complaints of pets being killed by coyotes have increased\nwith urbanization (Howell 1982). Also, the increase in the number of reported\nhuman attacks has created additional concern for urban dwellers. Avocado\nproducers using drip irrigation systems report that coyotes chew holes in\nplastic pipe and disrupt irrigation (Cummings 1973). Coyotes damage watermelons\nby biting holes through the melons and eating the centers out; raccoons, on the\nother hand, make small holes in the melons and scoop the pulp out with their\nfront paws. Coyotes will also damage other fruit crops. <\/p>\n\n\n

Wolves prey on larger ungulates such as caribou, moose, elk,\nand cattle. Wolves usually bring down these animals by cutting or damaging the\nmuscles and ligaments in the back legs or by seizing the victim in the flanks.\nSlash marks made by the canine teeth may be found on the rear legs and flanks.\nThe downed animals usually are disemboweled. <\/p>\n\n\n

Domestic dogs can be a serious problem to livestock,\nespecially to sheep pastured near cities and suburbs. Dogs often attack the\nhindquarters, flanks, and head of livestock. They rarely kill as effectively as\ncoyotes (Green et al. 1994). Normally, little flesh is consumed. Dogs are\nlikely to wound the animal in the neck and front shoulders; the ears often are\nbadly torn. Attacking dogs often severely mutilate the victim (Bowns and Wade\n1980). <\/p>\n\n\n

Coyote and dog tracks are similar but distinguishable. Dog\ntracks are round with the toes spread apart. Toenail marks are usually visible\non all toes (Dorsett 1987). Coyote tracks are more rectangular and the toes are\ncloser together. If any toenail marks show, they are usually of the middle\ntoes. Also, coyote tracks appear in a straight line whereas those of a dog are\nstaggered. <\/p>\n\n\n

\"\"<\/figure>\n\n\n

Foxes<\/a> <\/h3>\n\n\n

Gray and red foxes feed primarily on rabbits, hares, small\nrodents, poultry, birds, and insects. They also consume fruits. The gray fox\neats fish, a prey seldom eaten by the red fox. Gray and especially red foxes\nkill young live-stock, although poultry is their more common domestic prey.\nFoxes usually attack the throat of lambs and birds, but kill some by multiple\nbites to the neck and back (Wade and Bowns 1982). Normally, foxes taking fowl\nleave behind only a few drops of blood and feathers and carry the prey away\nfrom the kill location, often to a den. Eggs are usually opened enough to be\nlicked out. The shells are left beside the nest and are rarely removed to the\nden, even though fox dens are noted for containing the remains of their prey,\nparticularly the wings of birds. <\/p>\n\n\n

Einarsen (1956) noted that the breast and legs of birds\nkilled by foxes are eaten first and the other appendages are scattered about.\nThe toes of the victims are usually drawn up in a curled position because of\ntendons pulled when the fox strips meat from the leg bone. Smaller bones are\nlikely to be sheared off. The remains are often partially buried. <\/p>\n\n\n

Like other wild canids, foxes will return to established\ndenning areas year after year. They dig dens in wooded areas or open plains.\nHollow logs are also used. Dens may be identified by the small doglike tracks\nor by fox hairs clinging to the entrance. The gray fox is the only fox that\nreadily climbs trees, sometimes denning in a hollow cavity. <\/p>\n\n\n

Hogs<\/a> <\/h3>\n\n\n

Problems associated with feral or wild hogs have increased\nacross the southern United States. Rooting and wallowing by wild hogs can\ndamage agricultural crops and timber and also damage farm ponds and irrigation\ndikes (Barrett 1994). Wild hogs also feed on young sheep and goats in certain\nparts of the United States. The losses are difficult to determine at times\nbecause almost the entire carcass is either eaten or carried off and the only\nevidence may be tracks and blood where feeding occurred (Wade and Bowns 1982). <\/p>\n\n\n

Tracks of adult hogs resemble those made by a 200-pound\n(90-kg) calf. In soft ground dewclaws will show on adult hog tracks (Barrett\n1994). <\/p>\n\n\n

Mountain Lions<\/a> <\/h3>\n\n\n

Often called cougar or puma, this large feline preys on deer, elk, and domestic stock, particularly horses, sheep, goats, and cattle. It also eats rodents and other small mammals, when available. In one situation, according to Young (1933), a lone lion attacked a herd of ewes and killed 192 in one night. How-ever, 5 to 10 sheep killed in a single night is more typical (Shaw 1983). <\/p>\n\n\n

\"\"<\/figure>\n\n\n

Mountain lions, having relatively short, powerful jaws, kill\nwith bites inflicted from above, often severing the vertebral column and breaking\nthe neck. They also kill by biting through the skull (Bowns 1976). Lions usually\nfeed first on the front quarters and neck region of their prey. The stomach is\ngenerally untouched. The large leg bones may be crushed and the ribs broken.\nMany times, after a lion has made a kill, the prey is dragged or carried into\nbushy areas and covered with litter. A lion might return to feed on a kill for\nthree or four nights. They normally uncover the kill at each feeding and move\nit from 11 to 27 yards (10 to 25 m) to recover it. After the last feeding the\nremains may be left uncovered, and a search of the area might reveal previous\nburial sites (Shaw 1983). <\/p>\n\n\n

Adult lion tracks are approximately 4 inches (10 cm) in length and 4 1\/4 inches (11 cm) in width; they have four well-defined impressions of the toes at the front, roughly in a semicircle. Lions have retractable claws; therefore, no claw prints will be evident. The untrained observer sometimes con-fuses large dog tracks with those of the lion; however, dog tracks normally show distinctive claw marks, are less round than lion tracks, and have distinctly different rear pad marks. <\/p>\n\n\n

\"\"<\/figure>\n\n\n

Opossums <\/h3>\n\n\n

Opossums are omnivorous and occasionally eat fish,\ncrustaceans, insects, mushrooms, fruits, vegetables, eggs, and carrion. They\nwill also raid poultry houses. The opossum usually kills one chicken at a time,he skull (Bowns 1976). Lions usually\nfeed first on the front quarters and neck region of their prey. The stomach is\ngenerally untouched. The large leg bones may be crushed and the ribs broken.\nMany times, after a lion has made a kill, the prey is dragged or carried into\nbushy areas and covered with litter. A lion might return to feed on a kill for\nthree or four nights. They normally uncover the kill at each feeding and move\nit from 11 to 27 yards (10 to 25 m) to recover it. After the last feeding the\nremains may be left uncovered, and a search of the area might reveal previous\nburial sites (Shaw 1983). <\/p>\n\n\n

Adult lion tracks are approximately 4 inches (10 cm) in length and 4 1\/4 inches (11 cm) in width; they have four well-defined impressions of the toes at the front, roughly in a semicircle. Lions have retractable claws; therefore, no claw prints will be evident. The untrained observer sometimes con-fuses large dog tracks with those of the lion; however, dog tracks normally show distinctive claw marks, are less round than lion tracks, and have distinctly different rear pad marks. <\/p>\n\n\n

\"\"<\/figure>\n\n\n

Opossums <\/h3>\n\n\n

Opossums are omnivorous and occasionally eat fish,\ncrustaceans, insects, mushrooms, fruits, vegetables, eggs, and carrion. They\nwill also raid poultry houses. The opossum usually kills one chicken at a time,\noften mauling the victim (Burkholder 1955). Eggs will be mashed and messy, the\nshells often chewed into small pieces and left in the nest. Opossums usually\nbegin feeding on poultry at the cloacal opening. <\/p>\n\n\n

Young poultry or game birds are consumed entirely and only a\nfew wet feathers left. <\/p>\n\n\n

\"\"<\/figure>\n\n\n

Raccoons <\/h3>\n\n\n

Raccoons eat mice, small birds, snakes, frogs, insects,\ncrawfish, grass, berries, acorns, corn, melons \u2014 the list is almost endless.\nGarbage cans and dumps can be a major source of food in urban areas. Field crops\nor gardens near wooded areas may suffer severe damage from raccoons. Ripening\ncorn is frequently eaten and much is wasted (Conover 1987). They raid nesting\ncavities of birds (Lacki et al. 1987). They will on occasion kill small lambs,\nusually by chewing the nose. <\/p>\n\n\n

Occasionally, raccoons enter poultry houses and take several\nbirds in one night. The breast and crop can be torn and chewed, and the\nentrails some-times are eaten. There may be bits of flesh near water. Eggs may\nbe removed from poultry or game bird nests and eaten away from the nest.\nRearden (1951) found that eggshells were located within 28 feet (9 m) of the\nnest. <\/p>\n\n\n

The raccoon leaves a distinctive five-toed track that\nresembles a small human hand print. Tracks are usually paired, the left hind\nfoot beside the right forefoot (Murie 1954). Raccoon and opossum tracks can be\ndifficult to distinguish in soft sand where toes do not show. <\/p>\n\n\n

Skunks <\/h3>\n\n\n

Insects, particularly grasshoppers, beetles, and crickets,\nmake up a large portion of the skunk\u2019s diet. Skunks usually dig small cone-shaped\nholes in lawns, golf courses, and meadows in search of beetle larvae. A common\ncomplaint of objectionable odor occurs when skunks take up residence under\nbuildings. Skunks may depredate bee-hives. <\/p>\n\n\n

\"\"<\/figure>\n\n\n

Skunks kill few adult birds, but are serious nest robbers\n(Einarsen 1956). Eggs are usually opened at one end; the edges are crushed as\nthe skunk punches its nose into the hole to lick out the contents (Einarsen\n1956, Davis 1959). The eggs may appear to have been hatched, except for the\nedges. When in a more advanced stage of incubation, eggs are likely to be\nchewed in small pieces. Eggs may be removed from the nest, but rarely more than\n3 feet (1 m) away. <\/p>\n\n\n

Most rabbit, chicken, and pheasant carcasses found at skunk\ndens are carrion that have been dragged to the den sites (Crabb 1948). When\nskunks kill poultry, they generally kill only one or two birds and maul them\nconsider-ably. Crabb (1941) observed that spotted skunks help control rats and\nmice in grain storage buildings. They kill these rodents by biting and chewing\nthe head and foreparts; the carcasses are not eaten. <\/p>\n\n\n

Inhabited dens can be recognized by fresh droppings\ncontaining undigested insect parts near the mound or hole. Hair and rub marks\nalso may be present. Dens usually have a characteristic skunk odor, although\nthe odor may not be strong. <\/p>\n\n\n

Weasels and Mink <\/h3>\n\n\n

Weasels and mink have similar feeding behaviors, killing\nprey by biting through the skull, upper neck, or jugular vein (Cahalane 1961).\nWhen they raid poultry houses at night, they often kill many birds, eating only\nthe heads of the victims. Predation by rats usually differs in that portions of\nthe body are eaten and carcasses are dragged into holes or concealed places. <\/p>\n\n\n

Errington (1943) noted that mink, while eating large\nmuskrats, make an opening at the back or side of the neck. As the mink eats\naway flesh and pieces of the adjacent hide, the ribs, head, and hindquarters\nare pulled out through the same hole and the animal is skinned. McCracken and\nVan Cleve (1947) noted similar feeding behavior by weasels eating small\nrodents. <\/p>\n\n\n

\"\"<\/figure>\n\n\n

Teer (1964) observed that blue-winged teal eggs destroyed by\nweasels were broken at the ends and had openings 1\/2 to 3\/4 inch (1.5 to 2.0\ncm) in diameter. Close inspection of shell remains frequently will disclose\nfinely chewed edges and tiny tooth marks (Rearden 1951). <\/p>\n\n\n

Weasels den in the ground (for example, in a mole or pocket\ngopher burrow), under a barn, in a pile of stored hay, or under rocks. Mink dig\ndens approximately 4 inches (10 cm) in diameter into banks. Mink also use\nmuskrat burrows, holes in logs and stumps, and other natural shelters. <\/p>\n\n\n

Domestic Cats <\/h3>\n\n\n

Domestic cats rarely prey on anything larger than ducks,\npheasants, rabbits, or quail. Einarsen (1956) noted the messy feeding behavior\nof these animals. Portions of their prey are often strewn over several square yards\n(m) in open areas. The meaty portions of large birds are consumed entirely,\nleaving loose skin with feathers attached. Small birds are generally consumed\nand only the wings and scattered feathers remain. Cats usually leave tooth\nmarks on every exposed bone of their prey. Nesting birds are particularly\nvulnerable to cat predation. In areas managed for game birds or waterfowl\nproduction, vagrant cat control is almost a necessity. Unlike their native\ncousins, domestic cats are observed readily in the daytime, although feral cats\nare often extremely wary. <\/p>\n\n\n

Acknowledgments <\/h2>\n\n\n

This chapter was adapted with permission from R. A. Dolbeer, N. R. Holler, and D. W. Hawthorne. 1994. Identification\nand Control of Wildlife Damage. <\/em>T. A. Bookhout, ed. Research and management\ntechniques for wildlife and habitats. The Wildlife Society, Bethesda, Maryland.\n1994. <\/p>\n\n\n

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Cook, R. S., M. White, D. O. Trainer, and W. C. Glazener.\n1971. Mortality of young white-tailed deer fawns in south Texas. J. Wildl.\nManage. 35:47-56. <\/p>\n\n\n

Cowardin, L. M., D. S. Gilmer, and C. W. Shaiffer. 1985.\nMallard recruitment in the agricultural environment of North Dakota. Wildl.\nMonogr. 92:1-37. <\/p>\n\n\n

Crabb, W. D. 1941. Civits are rat killers. Iowa Farm Sci.\nRep. 2(1):12-13. <\/p>\n\n\n

Crabb, W. D. 1948. The ecology and management of the prairie\nspotted skunk in Iowa. Ecol. Monogr. 18:201-232. <\/p>\n\n\n

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Woronecki, P. P., R. A. Stehn, R. A. Dolbeer. 1980.\nCompensatory response of maturing corn kernels following simulated damage by\nbirds. J. Appl. Ecol. 17:737-746. <\/p>\n\n\n

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Editors<\/a> <\/h3>\n\n\n

Scott E. Hygnstrom<\/p>\n\n\n

Robert M. Timm<\/p>\n\n\n

Gary E. Larson<\/p>\n","protected":false},"excerpt":{"rendered":"

Richard A. Dolbeer .Project Leader Denver. Wildlife Research Center USDA-APHIS- Animal Damage Control, Sandusky, Ohio 44870 Nicholas R. Holler .Unit … Continue reading Damage Identification<\/span> →<\/span><\/a><\/p>\n","protected":false},"author":5,"featured_media":0,"parent":409,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-3188","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/nwco.net\/index.php?rest_route=\/wp\/v2\/pages\/3188"}],"collection":[{"href":"https:\/\/nwco.net\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/nwco.net\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/nwco.net\/index.php?rest_route=\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/nwco.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=3188"}],"version-history":[{"count":0,"href":"https:\/\/nwco.net\/index.php?rest_route=\/wp\/v2\/pages\/3188\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/nwco.net\/index.php?rest_route=\/wp\/v2\/pages\/409"}],"wp:attachment":[{"href":"https:\/\/nwco.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=3188"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}