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Common Rat

Rattus norvegicus

Mice and rats are some of the most troublesome and damaging rodents in the United States. They eat and contaminate food, damage structures and property, and transmit parasites and diseases to other animals and humans.

Location: Throughout the United States.

Hosts:  Norway rats eat a wide variety of foods but mostly prefer cereal grains, meats, fish, nuts, and some fruits. Like Norway rats, roof rats eat a wide variety of foods, but they prefer fruits, nuts, berries, slugs, and snails. Roof rats are especially fond of avocados and citrus, and they often eat fruit that is still on the tree.

Biology: Rats, like house mice, are active mostly at night. They have poor eyesight, but they make up for this with their keen senses of hearing, smell, taste, and touch. Rats constantly explore and learn, memorizing the locations of pathways, obstacles, food and water, shelter, and features of their environment.

Damage: Rats eat and contaminate foodstuffs and animal feed. They also damage containers and packaging materials in which foods and feed are stored. Both rat species cause problems by gnawing on electrical wires and wooden structures such as doors, ledges, corners, and wall material, and they tear up insulation in walls and ceilings for nesting.

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Canis latrans

Coyotes are medium-sized members of the dog family, larger than foxes but smaller than wolves that damage California’s pets, irrigation systems, livestock and other valued wild animals.

Location: California, All over the United States

Hosts: Pets in suburban areas, plastic drip irrigation systems in vineyards and orchards, livestock on rangelands, and other valued wild animals.

Biology: Coyotes are medium-sized members of the dog family, larger than foxes but smaller than wolves. Native to western North America, they are extremely adaptable.

Damage: Coyotes come into conflict with humans in a variety of ways, from chasing and attacking pets in suburban areas, to chewing plastic drip irrigation systems in vineyards and orchards, killing livestock on rangelands, or killing other valued wild animals.

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Feral Pigs

Sus scrofa

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According to the USDA, feral swine damage is often caused at night when the animals are most active. The best way to tell if feral swine are active in your area is to look for common signs of rooting, rubbing, wallowing, tracks, and trails.

Location: California

Impact Significance:

Feral swine are quickly spreading across the United States due to natural population growth, illegal movement by sports hunters, and escapes from domestic swine operations. Experts estimate their
numbers at over 5 million animals nationwide.

Though a rare occurrence, feral swine can directly infect people with diseases. Pseudorabies can be transmitted from feral swine to some pets, such as dogs and cats, as well as cattle, sheep, and goats.

Hosts: Feral swine eat and destroy field crops such as corn, milo, rice, watermelon, spinach, peanuts, hay, turf, and wheat. Additionally, their rooting activities destroy native vegetation, and invasive plants often re-vegetate damaged areas, reducing native plants and grasses. Their wallowing activities can contaminate water supplies and impact water
quality. These animals have also been known to destroy livestock and game fences and consume livestock feed, minerals, and protein supplements.


Feral swine are an invasive species. They are not native to the United States and should not be confused with the collared peccary (javelina), a native pig-like mammal of the Southwest. Due to their extensive crossbreeding, feral swine often vary in appearance and can be mistaken for domestic pigs.


It is estimated that feral swine in the United States cause more than $1.5 billion in damages and control costs each year.


The opossum, Didelphis virginiana, is the only native North American marsupial.

Location: California

Hosts: Fruits, nuts, green plants, insects, snails, snakes, frogs, birds and their eggs, and small mammals such as meadow voles, mice, and rats.

Biology: The only marsupial (pouched mammal) found in the United States and Canada. A female opossum gives birth to helpless young as tiny as honeybees.

Damage: Opossums are considered a nuisance in gardens and near homes where they feed on berries, grapes, tree fruits and nuts, and defecate on garden paths and patios. They get into fights with dogs and cats and can inflict serious injury with their mouthful of sharp pointed teeth.

Opossums carry diseases such as leptospirosis, tuberculosis, relapsing fever, tularemia, spotted fever, toxoplasmosis, coccidiosis, trichomoniasis, and Chagas disease. They may also be infested with fleas, ticks, mites, and lice. Opossums are hosts for cat and dog fleas, especially in urban environments.

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The adult raccoon, Procyon lotor, is a stocky mammal about 2 to 3 feet long and weighs 7 to 30 pounds.

Location: California

Hosts: Plant foods including all kinds of fruits, berries, nuts, acorns, corn, and other types of grain. Animal foods including crayfish, clams, fish, frogs, snails, insects, turtles, rabbits, muskrats, and the eggs and young of ground-nesting birds, including waterfowl.

Biology: Procyon is a genus of nocturnal mammals, comprising three species commonly known as raccoons, in the family Procyonidae.

Damage: Common problems occur when raccoons look for nesting sites in buildings. Females in search of nesting sites may rip off shingles, fascia boards, or rooftop ventilators to get into the attic. Once inside the attic, insulation on walls may be torn up and displaced; and insulation on heating and air conditioning ducts may be ripped off and destroyed.

Raccoon damage to gardens is quite common.

Raccoons are known to carry a number of diseases and internal parasites.

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Procyon lotor

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