Carnivores and Mammalian Predators
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- Predation is rarely observed; therefore, the accurate assessment of losses to specific predators often requires careful investigative work.
- Determine cause of death by checking for signs on the animal and around the kill site.
- Size and location of tooth marks will often indicate the species causing predation.
- Extensive bleeding usually is characteristic of predation. Where external bleeding is not apparent, the hide can be removed from the carcass, particularly around the neck, throat, and head, and the area checked for tooth holes, subcutaneous hemorrhage, and tissue damage. Hemorrhage occurs only if skin and tissue damage occurs while the animal is alive. Animals that die from causes other than predation normally do not show external or subcutaneous bleeding, although bloody fluids may be lost from body openings. Animal losses are easiest to evaluate if examination is conducted when the carcass is still fresh. Animals may not always be killed by a throat attack, but may be pulled down from the side or rear. Blood is often on the sides, hind legs, and tail areas. Calves can have their tails chewed off and the nose may have tooth marks or be completely chewed by the predator when the tongue is eaten.
- Tracks and droppings alone are not proof of depredation or of the species responsible. They are evidence that a particular predator is in the area and, when combined with other characteristics of depredation, can help determine what species is causing the problem.
- Eat primarily rodents such as mice, prairie dogs, pocket gophers, and ground squirrels. They will also prey on rabbits, especially the young. Badgers usually eat all of a prairie dog except the head and fur along the back. This characteristic probably holds true for most of the larger rodents they eat; however, signs of digging near prey remains are the best evidence of badgers.
- Destroy nests of ground-nesting birds and occasionally kill small lambs and poultry, parts of which they sometimes bury in holes resembling their dens.
- Den in crop fields.
- Tracks often appear similar to coyote tracks but on close examination they are distinctively “pigeon-toed” with impressions from the long toenails apparent in most situations.
- Prey on livestock. Black bears usually kill by biting the neck or by slapping the victim. Torn, mauled, and mutilated carcasses are characteristic of bear attacks. Often, the bear will eat the udders of female prey, possibly to obtain milk. The victim usually is opened ventrally and the heart and liver are consumed. The intestines are often spread out around the kill site, and the animal may be partially skinned while the carcass is fed upon. Smaller livestock such as sheep and goats may be consumed almost entirely, and only the rumen, skin, and large bones left.
- Feces are generally found within the kill area, and a bedding site is often found nearby. Bears use their feet while feeding so they do not slide the prey around as do coyotes.
- If the kill is made in the open, it may be moved to a more secluded spot. The grizzly has a feeding and killing pattern similar to that of the black bear. Murie (1948) found that most cattle are killed by a bite through the back of the neck. Large prey often have claw marks on the flanks or hams. The prey’s back is sometimes broken in front of the hips where the bear simply crushed it down. Young calves are occasionally bitten through the forehead. The presence of bears has stampeded range sheep, resulting in death from suffocation or from falls over cliffs.
- A marauding bear searching for food may also play havoc with garbage cans, cabins, camp sites, and apiaries. The bear track resembles that of a human, but has distinctive claw marks. The little inside toes often leave no marks in dust or shallow mud so the print appears to be four-toed (Murie 1954).
- Occasionally prey on sheep, goats, deer, and pronghorns; however, they more commonly kill smaller animals such as porcupines, poultry, rabbits, rodents, birds, and house cats. Bobcats characteristically kill adult deer by leaping on their back or shoulders, usually when the victim is lying down, and biting them on the trachea. The jugular vein may be punctured, but the victims usually die of suffocation and shock.
- Look for hemorrhages caused by claws on both sides of the carcass.
- Small fawns, lambs, and other small prey are often killed by a bite through the top of the neck or head. The hindquarters of deer or sheep are usually preferred by bobcats, although the shoulder and neck region or the flank are sometimes eaten first. The rumen is often untouched. Poultry are usually killed by biting the head and neck; the heads are usually eaten. Also, both species reportedly prey on bird eggs. Bobcat and lynx droppings are similar; in areas inhabited by both species, the tracks will help determine the responsible animal. The lynx has larger feet with much more hair and the toes tend to spread more than they do on the more compact bobcat tracks.
- Feline predators usually attempt to cover their kills with litter. Bobcats reach out 12 to 14 inches (30 to 35 cm) in scratching litter, compared to a 35-inch (90-cm) reach of a mountain lion (Young 1958).
- Canine teeth marks will also help distinguish a lion kill from that of a bobcat—1 1/2 inches (3.8 cm) for a lion versus 3/4 to 1 inch (1.9 to 2.5 cm) for a bobcat.
- Prey on big game, livestock, rodents, wild birds, and poultry. Coyotes are the most common and most serious predator of livestock in the United States.
- Coyotes normally kill livestock with a bite in the throat, but they infrequently pull the animal down by attacking the side, hindquarters, and udder. The rumen and intestines may be removed and dragged away from the carcass. On small lambs, the upper canine teeth may penetrate the top of the neck or the skull. Calf predation by coyotes is most common when calves are young. Calves that are attacked, but not killed, exhibit wounds in the flank, hindquarters, or front shoulders; often their tails are chewed off near the top. Deer carcasses are frequently completely dismembered and eaten.
- Drip irrigation system users report that coyotes chew holes in plastic pipe and disrupt irrigation. Coyotes damage watermelons by biting holes through the melons and eating the centers out; raccoons, on the other hand, make small holes in the melons and scoop the pulp out with their front paws. Coyotes will also damage other fruit crops.
- Wolves prey on larger ungulates such as caribou, moose, elk, and cattle. Wolves usually bring down these animals by cutting or damaging the muscles and ligaments in the back legs or by seizing the victim in the flanks. Slash marks made by the canine teeth may be found on the rear legs and flanks. The downed animals usually are disemboweled.
- Domestic dogs can be a serious problem to livestock, especially to sheep pastured near cities and suburbs. Dogs often attack the hindquarters, flanks, and head of livestock. They rarely kill as effectively as coyotes. Normally, little flesh is consumed. Dogs are likely to wound the animal in the neck and front shoulders; the ears often are badly torn. Attacking dogs often severely mutilate the victim. Coyote and dog tracks are similar but distinguishable. Dog tracks are round with the toes spread apart. Toenail marks are usually visible on all toes (Dorsett 1987). Coyote tracks are more rectangular and the toes are closer together. If any toenail marks show, they are usually of the middle toes. Also, coyote tracks appear in a straight line whereas those of a dog are staggered.
- Rarely prey on anything larger than ducks, pheasants, rabbits, or quail. They tend to be messy eaters, with portions of their prey are often strewn over several square yards (m) in open areas. The meaty portions of large birds are consumed entirely, leaving loose skin with feathers attached. Small birds are generally consumed and only the wings and scattered feathers remain.
- Cats usually leave tooth marks on every exposed bone of their prey.
- Gray and red foxes feed primarily on rabbits, hares, small rodents, poultry, birds, and insects. They also consume fruits. The gray fox eats fish, a prey seldom eaten by the red fox. Gray and especially red foxes kill young livestock, although poultry is their more common domestic prey. Foxes usually attack the throat of lambs and birds, but kill some by multiple bites to the neck and back. Normally, foxes taking fowl leave behind only a few drops of blood and feathers and carry the prey away from the kill location, often to a den. Eggs are usually opened enough to be licked out. The shells are left beside the nest and are rarely removed to the den, even though fox dens are noted for containing the remains of their prey, particularly the wings of birds.
- Breast and legs of birds killed by foxes are eaten first and the other appendages are scattered about. The toes of the victims are usually drawn up in a curled position because of tendons pulled when the fox strips meat from the leg bone. Smaller bones are likely to be sheared off. The remains are often partially buried.
- Foxes will return to established denning areas year after year. They dig dens in wooded areas or open plains. Hollow logs are also used. Dens may be identified by the small doglike tracks or by fox hairs clinging to the entrance. The gray fox is the only fox that readily climbs trees, sometimes denning in a hollow cavity.
- Wild hogs also feed on young sheep and goats; typically almost the entire carcass is either eaten or carried off and the only evidence may be tracks and blood where feeding occurred.
- Tracks of adult hogs resemble those made by a 200-pound (90-kg) calf. In soft ground dewclaws will show on adult hog tracks.
- Prey on deer, elk, and domestic stock, particularly horses, sheep, goats, cattle, rodents and other small mammals, when available.
- Can kill large numbers of animals in one night, eg. a lone lion attacked a herd of ewes and killed 192 in one night. However, 5 to 10 sheep killed in a single night is more typical.
- Mountain lions, having relatively short, powerful jaws, kill with bites inflicted from above, often severing the vertebral column and breaking the neck. They also kill by biting through the skull.
- Lions usually feed first on the front quarters and neck region of their prey. The stomach is generally untouched. The large leg bones may be crushed and the ribs broken. Many times, after a lion has made a kill, the prey is dragged or carried into bushy areas and covered with litter. A lion might return to feed on a kill for three or four nights. They normally uncover the kill at each feeding and move it from 11 to 27 yards (10 to 25 m) to recover it. After the last feeding the remains may be left uncovered, and a search of the area might reveal previous burial sites.
- Adult lion tracks are approximately 4 inches (10 cm) in length and 4 1/4 inche (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 confuses 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.
- Omnivorous eating fish, crustaceans, insects, mushrooms, fruits, vegetables, eggs, and carrion. They will raid poultry houses, usually killing one chicken at a time, often mauling the victim.
- Eggs will be mashed and messy, the shells often chewed into small pieces and left in the nest. Opossums usually begin feeding on poultry at the cloacal opening. Young poultry or game birds are consumed entirely and only a few wet feathers left.
- Eat mice, small birds, snakes, frogs, insects, crawfish, grass, berries, acorns, corn, melons — the list is almost endless. Garbage cans and dumps can be a major source of food in urban areas. Field crops or gardens near wooded areas may suffer severe damage from raccoons. Ripening corn is frequently eaten and much is wasted. They raid nesting cavities of birds. They will on occasion kill small lambs, usually by chewing the nose.
- Raccoons enter poultry houses and take several birds in one night. The breast and crop can be torn and chewed, and the entrails sometimes are eaten. There may be bits of flesh near water.
- Eggs may be removed from poultry or game bird nests and eaten away from the nest, usually within 28 feet (9 m) of the nest.
- A distinctive five-toed track that resembles a small human hand print. Tracks are usually paired, the left hind foot beside the right forefoot. Raccoon and opossum tracks can be difficult to distinguish in soft sand where toes do not show.
- Insects, particularly grasshoppers, beetles, and crickets, make up a large portion of the skunk’s diet. Skunks usually dig small cone-shaped holes in lawns, golf courses, and meadows in search of beetle larvae. A common complaint of objectionable odor occurs when skunks take up residence under buildings. Skunks may depredate beehives.
- Skunks kill few adult birds, When skunks kill poultry, they generally kill only one or two birds and maul them considerably. Crabb (1941) observed that spotted skunks help control rats and mice in grain storage buildings. They kill these rodents by biting and chewing the head and foreparts; the carcasses are not eaten.
- Skunks are serious nest robbers. Eggs are usually opened at one end; the edges are crushed as the skunk punches its nose into the hole to lick out the contents. The eggs may appear to have been hatched, except for the edges. When in a more advanced stage of incubation, eggs are likely to be chewed in small pieces. Eggs may be removed from the nest, but rarely more than 3 feet (1 m) away.
- Most rabbit, chicken, and pheasant carcasses found at skunk dens are carrion that have been dragged to the den sites.
Inhabited dens can be recognized by fresh droppings containing undigested insect parts near the mound or hole. Hair and rub marks also may be present. Dens usually have a characteristic skunk odor, although the odor may not be strong.
- Snake predation is very hard to identify because they consume their prey whole, often leaving no clues. Note the image of a black rat snake eating an egg. (Photo courtesy of Raymond Norcia). The snake will completely consume the egg. So the only sign will be a missing egg, unlike raccoon or skunk which will leave egg shell behind.
- Look for snake skins.
- Consider if any holes are large enough to allow a snake to enter and exit after it has eaten. Size will vary depending on size of snake. Typically snakes able to enter through 1/4-inch gaps or smaller will not cause predation damage.
- Weasels and mink have similar feeding behaviors, killing prey by biting through the skull, upper neck, or jugular vein.
- In poultry houses, they often kill many birds, eating only the heads of the victims. Predation by rats usually differs in that portions of the body are eaten and carcasses are dragged into holes or concealed places. One farmer suggested that weasels and mink attack hens underneath the wing.
- While eating large muskrats, make an opening at the back or side of the neck. As the mink eats away flesh and pieces of the adjacent hide, the ribs, head, and hindquarters are pulled out through the same hole and the animal is skinned. Similar feeding behavior by weasels occurs when they eat small rodents.
- Weasels eat eggs by breaking in at the ends. (openings 1/2 to 3/4 inch (1.5 to 2.0 cm) in diameter). Close inspection of shell remains frequently will disclose finely chewed edges and tiny tooth marks.