• There are approximately fourty species that inhabit the United States. Eight species are common in Pennsylvania.  All bats in Pennsylvania eat insects and capture their prey in flight.  A single bat, for instance, may consume as many as 2,000 insects every night. They generally roost in caves, tree hollows and other natural locations; but they can take up residence in buildings and attics during the warm weather months to breed. They live in colonies so early detection is important to avoid an infestation.
  •  Bats do not damage or destroy property by gnawing or chewing, but their droppings and urine may cause odor problems. More importantly their waste can lead to respiratory problems in humans.  Histoplasmosis is a disease caused by the fungus Histoplasma capsulatum. Its symptoms vary greatly, but the disease primarily affects the lungs. H. capsulatum grows in soil and material contaminated with bat and bird droppings.  Spores become airborne when contaminated soil is disturbed.  Breathing the spores causes infection.
  • Because bats feed on insects, they are beneficial to the environment and should not be needlessly destroyed.  Bats are protected by Pennsylvania game laws when flying and hibernating. 
  • One important aspect to consider before bat-proofing your building is the timing of the procedure. Because pups remain confined in the roost until they are old enough to fly, bat-proofing should never be completed from late May through mid July.  Otherwise the young, flightless bats would be trapped inside the building.  Bat-proofing during these months would result in potential health risks and obvious odor problems as the young bats die and decay inside the building.  Also, the pups may enter human living areas in search of a way out, and females may frantically attempt to reenter the building to rejoin their young.  Removal of bats should be done by a professional, both for your safety and the bat colony.
  • The incidence of rabies in the wild bat population is l, and the spread of rabies within individual colonies appears to be very rare.  Surveys of wild bats in the United States and Canada indicate the incidence of rabies in clinically normal bats is less than 0.5 percent.


Skunks are well known, nocturnal residents of Pennsylvania. Skunks have earned their negative reputation through the odor of their musk. The repugnant odor lingers for days and can be nauseating. In addition, skunks sometimes set up their dens too close to a human dwelling or dig in a well manicured lawn for insects. Their spray can extend to 12 feet, burning the eyes of an attacker or curious house pet, causing temporary blindness. 

Adult skunks begin breeding in late February through late March.  Older females bear their young during the first part of May, while yearling females bear their young in early June. There usually is only one litter annually. Litters commonly consist of 4 to 6 young.

The normal home range of the skunk is .5 to 2 miles in diameter.  Skunks are dormant for about a month during the coldest part of winter.  They may den together in winter for warmth, but generally are not sociable.

Skunks can carry rabies.  When a skunk becomes infected with the virus, it may not be apparent for many days.  Any skunk showing abnormal behavior, such as daytime activity, may be rabid and should be treated with caution. In addition, avoid overly aggressive skunks that approach without hesitation.  

These problems can be alleviated through various damage control techniques. DelVal wildlife nuisance control can remove skunks from your surroundings without any release of of their odor. Skunks are highly beneficial to farmers, gardeners, and landowners because they feed on large numbers of agricultural and garden pests.


Lets not forget that cute little furry animal is still a rodent and rodents chew and gnaw. In residential areas, squirrels cause damage because of their tendency to gnaw on structures. They will chew siding and under eaves to make openings for their nests. Once they have made a nest, squirrels will chew on insulation and the insulation around wires.  This habit is dangerous because the bare wires may cause a fire. They also travel along powerlines and may short out transformers.  So these cute little animals quickly become major nuisances to homeowners, businesses and industries alike. 

Gray squirrels breed in mid-December or early January and again in June.  When not breeding, the gray squirrel is solitary.  They usually have two litters of one to four pups.

Squirrels are not known as vectors for diseases.


Flying squirrels are smaller than other tree squirrels.  It can be difficult to distinguish between the two species of flying squirrels that occur in Pennsylvania; both may be various shades of gray or brown above and lighter below.  The most distinctive characteristics of flying squirrels are the broad webs of skin connecting the fore and hind legs at the wrists, and the distinctly flattened tail. They use this skin as a parachute when gliding from tree to tree.

Flying squirrels can have two litters of two to four young each year. The young may stay with the mother through the winter when the squirrels commonly group together. 

Flying squirrels are the only squirrels that are active at night.

Flying squirrels' food habits are generally similar to those of other squirrels. However, they are the most carnivorous of all tree squirrels.  They eat bird eggs and nestlings, insects, and other animal matter when available.

Flying squirrels are carriers of a variety of parasites (raccoon roundworm) that can transfer diseases to humans. 

Flying squirrels can chew their way into attics to take up residence.


The woodchuck, also known as the groundhog or whistle pig, is one of Pennsylvania's most widely distributed mammals.  In general, groundhogs prefer to construct their burrows in open farmland and in the wooded or bushy areas adjacent to open land. However, they also can be found in suburban areas where the combination of food and cover provides satisfactory habitat.

A woodchuck's burrow serves as home to the woodchuck for mating, raising young, hibernating, and escaping danger. Once occupied, a burrow system may be used for several seasons.  Old burrows not in use by woodchucks provide cover for rabbits, weasels and other wildlife.

Woodchucks primarily feed in the early morning and evening hours.  They are strict herbivores and feed on a variety of vegetable, grasses, and legumes.  Preferred foods include soybeans, beans, peas, carrot tops, alfalfa, clover, and grasses.  When not feeding, they sometimes bask in the sun during the warmest periods of the day.

Woodchucks are among the few mammals that enter into true hibernation.  Hibernation varies with latitude, but generally begins near the end of October or early November and continues until late February and March.  

On occasion the woodchuck's feeding and burrowing habits conflict with human interests.  Damage often occurs on farms, in home gardens, orchards, nurseries, and around buildings.  A homeowner may lose their entire tomato patch.  Fruit trees and ornamental shrubs may be damaged by woodchucks as they gnaw on woody vegetation.

Groundhogs can carry rabies and parasites that can infect people and pets.


There are over 30 species of fox living in an amazing variety of environments all over the world. In general, foxes are small members of the dog family, the largest of which is the typical red fox. Red and grey foxe found throughout Pennsylvania. The red fox in particular is extremely skilled at adapting to almost any environment. They have succeeded and thrived in close proximity to human beings and there are even some sub-species of red fox that live in heavy urban environments, taking advantage of their naturally nocturnal tendencies.

They are solitary hunters even if living in a family group, and they are notorious for killing extra prey and burying it for later. This activity is probably how the "sly" signature got attached to the fox, although, foxes, in general, are very bright, inquisitive and intelligent animals. 

Fox species don't bark like domestic dogs do. They have a warning bark of their own that is very short, high-pitched, and usually singular, definitely not a "bow-wow-wow" type sound.  

Fox vocalizations include chilling nighttime "screams", coyote-like howls, whimpers, "snuffing" noises, and a happy call that sounds like a human baby crying. But the most distinct sound most foxes make is a chuckling type noise called a "gekker".

Foxes are good for keeping rodent population under control. In farm areas, foxes are notorious for raiding the chicken coops along with attacks on other small animals and birds. As omnivores they will adapt to their environment for their food source as well as carrion in their diet.

They mate annually and typically will have a litter of six, three male and three female.

Foxes can carry the rabies diseases as well as distemper. They also can carry leas, ticks, parasites and mange all of which can be transferable to humans and domestic animals.


Chipmunks are sometimes confused with red squirrels but their distinctive light brown stripes down their back make them easy to recognize. Chipmunks are very vocal and emit a rather sharp "chuck-chuck-chuck" call. Red squirrels spend a great deal of time in trees: chipmunks, although they can climb tree, spend most of their time on the ground. 

Chipmunk burrows often are well hidden near objects or buildings (for example, stumps, wood or brush piles, basements and garages).  The burrow entrance usually is about 2 inches in diameter and is not surrounded by obvious mounds of dirt, because the chipmunk carries the dirt in its cheek pouches and scatters it away from the burrow.  In most cases, the burrow's main tunnel is 20 to 30 feet long.  Normally tunnels include a nesting chamber, one or two food storage chambers, various side pockets connected to the main tunnel, and separate escape tunnels.

With the onset of cold weather, chipmunks enter a period of inactivity that continues through the winter months. They do not enter a true hibernation, but instead rely on the cache of food they store in their burrows.

Chipmunks present in large numbers can cause structural damage by burrowing under patios, stairs, retention walls, or foundations.  They also may consume flower bulbs, seeds, or seedlings, as well as bird or grass seed and pet food not stored in  rodent proof containers.

Chipmunks mate two times a year, in early spring and again early in the summer.  They give birth to 2 to 5 young in April to May and again in August to October.

Chipmunks as well as mice are primary carriers of the deer tick.


Raccoons are noted for their intelligence, with studies showing that they are able to remember the solution to tasks for up to three years.  Raccoons have excellent senses of hearing, sight and smell. Two of the raccoon's most distinctive features are it's extremely dexterous front paws and its black facial mask. 

They adapt well to people and human activities; some raccoons live in cities, where they den in storm drains and attics and raid garbage cans and pet dishes. 

Breeding takes place in January or February. Following a 2-month gestation period, young are born in March and April. Usual litter size is 3 to 5 young, with 4 the average.

 If for some reason a female doesn’t breed in winter, she may become receptive later in the spring and bear young in the summer

Raccoons can carry rabies, a lethal disease carried in the saliva and transmitted by bites. Among the main symptoms for rabies in raccoons are a generally sickly appearance, impaired mobility, abnormal vocalization, and aggressiveness.  However there may be no visible signs at all.  Since healthy animals, especially nursing mothers, will occasionally forage during the day, daylight activity is not a reliable indicator of illness in a raccoon.  Raccoons become more susceptible to disease if they overpopulate an area, because they’ll encounter one another more often.

Raccoons raiding trash cans is a nuisance but raccoons in the attic or other spaces in the home can cause damages exceeding hundreds of dollars



The eastern coyote, Canis latrans, is found throughout the northeastern United States and southeastern Canada. Recent research shows the eastern coyote is an immigrant, the origin of which likely involved interbreeding between coyotes and gray wolves. The eastern coyote is the largest canine found in Pennsylvania.

The eastern coyote is much larger than its western counterpart. Adult males in Pennsylvania weigh 45 to 55 pounds. Females are smaller, weighing 35 to 40 pounds.        

Their pelage colors range from light blond to reddish blond to gray, and from dark brown washed with black to black. Generally, coyotes are gray to a German shepherd coloration. Their legs are gray, tan and reddish, often with black markings or lines down the front of the front legs.  

Coyotes are monogamous; they maintain pair bonds for several years. The social unit centers around the mated pair and its offspring.

They have one heat period that lasts four to five days, usually in February. The litters are born from mid-April to early May, and litter sizes average five to seven pups. Coyotes compensate for unusually high mortality by having larger litters. 

Coyotes use a variety of yips, barks and howls to communicate and periodically assemble into larger packs. Coyotes at times will "pack" and at other times will hunt alone or in the company of another coyote or two. They primarily are nocturnal, but often hunt during daylight hours, especially in the morning. Howling might occur at any time of day, but the highest activity usually is at night. A coyote's senses of smell, hearing and alertness are especially keen.  

Coyotes can carry rabies as well as parasites that can transmit disease to domestic pets and humans. 


The opossum is one of the world’s oldest species of mammal, and the only marsupial on our continent.  “Opossum” is derived from the Algonquin Indian word apasum, meaning “white animal.” A creature without specialized body structure or food preference, the opossum thrives in many settings. It is found throughout Pennsylvania.  

An opossum’s brain is small and of primitive structure. Senses of smell and touch are well developed, but hearing is not especially keen and eyesight is weak. When walking, an opossum sniffs the air and occasionally stops and stands on its hind feet to look around. Although normally silent, it may growl, hiss or click its teeth when annoyed. If an opossum is threatened and cannot climb a tree or hide in rocks or brush, it may crouch and defend itself — or, if struck, may feign death. When feigning death, also called “playing possum,” an individual lies limp and motionless, usually on its side. Its eyes and mouth remain open, its tongue protrudes, its forefeet clench, and its breathing becomes shallow. This state may last from a few minutes to several hours. 

Opossums are omnivorous and opportunistic — they eat whatever they can find.  Opossums eat more animal than plant food. They consume garbage and carrion, including animals killed on highways. Sometimes opossums forage by day, but they are mostly nocturnal.   Opossums do not dig their burrows, but they will occupy abandoned burrows.  They seldom spend two successive nights in the same den.

 Marsupials are born before they are well developed, compared to other mammals, and continue their growth and development in a pouch on their mother’s abdomen. Most litters vary from 5-13 young, averaging 8 (as many as 21 have been reported).   The pouch is lined with fur and contains mammary glands. The female usually has 13 mammary glands, so offspring in excess of this number die. The mother can close her pouch to keep the young from falling out.    Six to nine young usually survive to fend for themselves.

Opossums can carry rabies as well as fleas, ticks and parasites.


The beaver is North America’s largest rodent.  Beaver fur is thick and considered valuable. By the end of the nineteenth century, uncontrolled trapping had eliminated beavers in Pennsylvania and other states, but today this aquatic furbearer is back. 

Today, beavers are found throughout Pennsylvania. Beavers are shy and mainly nocturnal, but people interested in catching a glimpse of a beaver may get lucky by staking out a beaver pond in the early morning and near sundown.

A beaver’s front feet are remarkably dexterous. They have long claws and are used for digging, handling food and working on dams.  A beaver’s vision is weak, but its hearing and sense of smell are acute. Most food is located by smell. A beaver can stay submerged up to 15 minutes; membrane valves seal the ears and nostrils while it’s submerged.  

Because its front teeth never stop growing, a beaver must continually cut wood to offset incisor growth. The upper and lower incisors are the primary cutters. Beavers eat vegetable matter. They prefer soft plant foods, including grasses, ferns, mushrooms, duckweed, algae, and the leaves, stems and roots of water plants such as cattails and water lilies. When soft foods are available, beavers cut down few trees unless they’re needed for dam or lodge repair. They also eat the bark, twigs and buds of aspen, maple, willow, birch, black alder and black cherry trees.

Beavers build dams on streams and creeks. This building behavior appears to be instinctive rather than learned.   

Beavers can and do become troublesome for some people.  Water backed up by their dams floods pastures, crop fields and roads, disrupts public water supplies and kills trees. They also cut down valuable shade trees and excavate unwanted channels.




One of Pennsylvania's most efficient predators, mink are semi-aquatic members of the weasel family.          

A mink's coat is thick, full and soft. A short, tight layer of underfur is covered with longer guard hairs, which give the pelt its luster. Colors range from russet to a deep, chocolate brown.      

Mink are most active at night and early morning, although they sometimes venture out during the day.  Active year-round, mink may curl up and sleep for several days during winter cold spells. Like most mustelids, they are agile and fierce fighters.  Mice, voles and muskrats rank as most important foods of mink during all seasons.  Other prey include rabbits, shrews, fish, frogs, crayfish, insects, snakes, waterfowl and other birds, eggs, domestic poultry, earthworms and snails. Generally, a mink is an opportunist, feeding on whatever is most easily caught or found. Thus, it might avoid fighting to kill a healthy adult muskrat if crayfish were abundant and easily captured. Mink occasionally kill more than they can eat. In winter, they cache carcasses and revisit them to feed.           

Mink are basically solitary, except during mating season, when they use a powerful scent from their anal glands to attract mates.  Mating occurs from February to April, with most activity in March.  

Mink den in abandoned woodchuck tunnels, hollow logs, vacant muskrat lodges, holes in stone piles and beneath large tree roots. Dens are usually near water and may have more than one entrance.

Mink are extremely sensitive to environmental pollutants. At the top of the food chain in aquatic environments, they accumulate many chemical compounds and heavy metals in their tissue including polychlorinated biphenyls and mercury. Mink are often used as bio indicators of pollution in aquatic systems.  Mink live up to 10 years in captivity, and a wild one would be fortunate to survive two or three winters. Disease, road accidents, and regulated harvest are mortality factors.


Musk refers to a strong smelling substance released from the animal's perineal glands. Rat describes its rat-like appearance.  The muskrat is a rodent related not only to rats, but also to mice, voles, and beavers. The nation's most abundant furbearer, the muskrat lives on or near the still or slowmoving water of ponds, marshes, streams, and rivers and, to a lesser extent, faster streams. . Muskrats are common in Pennsylvania, though not nearly as abundant as they used to be.  They weigh 2 to 3 pounds; have a stout body; short legs; and an 8- to 12-inch tail that is flattened vertically, scaly, and practically hairless. 

To insulate against cold water, a muskrats underfur is dense, silky, and soft, overlain with long, dark brown guard hairs shading to gray-brown on the throat and belly. Overall pelt color can be chestnut brown to almost black, or any color in between. 

Muskrats build houses called lodges or huts, or burrow into stream banks, earthen dikes, and dams, often causing considerable damage.  Muskrats do not dam streams.  

Muskrats are tenacious fighters. Muskrats are parasitized by mites, fleas,flatworms, roundworms, and tapeworms. While the average lifespan is less than 12 months, some individuals may live five or six years.  

Muskrats also damage agricultural and ornamental crops near water and their tunnels riddle dams, dikes, and canal banks. This is a serious problem for which trapping is the most effective and least expensive solution.