Moles

There are seven North American mole species: the eastern mole, hairy-tailed mole, star-nosed mole, broad-footed mole, Townsend's mole, coast mole, and shrew mole. The most wide-ranging is the eastern mole, which is found from eastern Texas, north to southern South Dakota and eastward to the Atlantic Ocean.

Moles have a hairless, pointed snout and small eyes. The photo above is that of an eastern mole. These animals are insectivores and feed primarily on grubs and earthworms. For the most part, moles live in seclusion and underground burrows and rarely come to the surface. These mammals are solitary and rarely do more than 2 or 3 moles occupy the same burrow system.

Moles have a very high metabolic rate and, therefore, have to consume large amounts of food. The home range of these insectivores is almost 20 times larger than that of a pocket gopher. Our experience in studies of moles on golf courses has shown that an infested area will contain about one mole per acre. Because of the extensive tunneling and length of the tunnels, it may appear that many moles occupy an area.

Moles dig elaborate tunnel systems and have feeding runways barely beneath the grass. That is why a mole on a golf green can stick out like a sore thumb. The ridge is elevated and easily visible. The tunnel system will have many yards of traveling tunnels within several inches of the ground surface. As the weather cools, moles will retreat into their deeper tunnels, up to 5 feet beneath the surface.

Moles tend to be very aggressive and will kill and consume voles or mice that may venture into their tunnels. Numerous studies have been conducted on the food habits of moles. The mammal will consume about 85% of its body weight in food daily. A study on eastern moles revealed that the majority of food found in the stomach contained white grubs and earthworm. Beetles, beetle larvae, and other larvae were also present. Ants, wasps, flies and other various insects were also noted.

For the most part, moles prefer moist soil with high populations of grubs and earthworms. That is why moles are often a menace on golf courses and lawns. As you fertilize and care for grass, this attracts worms and grubs, which in turn attracts moles and provides a food base for the mammal.

Moles are not social animals. The gestation period for moles is about 42 days and they have an average of 5 young in March to April. Because of their behavior, moles have few predators. It is a rare occasion to see a mole as it moves near a tunnel entrance.

For the most part, baits have been used to control moles. Most are ineffective since most of these products contain grain-based material. The food habits of animals dictate the bait type. We have maintained moles in captivity by feeding the animals wet cat food. Because of our studies we have been able to determine which bait additives are best preferred by moles and have incorporated them into the formula. If you think you have a mole problem in your yard there is a simple technique to determine if a mole is the menace. Take the end of a broomstick and force it into the surface tunnel of the mole. Within 1-2 days if a mole is inhabiting the burrow, the hole will be neatly plugged with fresh dirt. Mark the spot where you punch the hole into the tunnel so you can be certain to locate where you punched the hole.

General Overview Mole-ology

Identification: This compact burrowing rodent is distinguished by naked pointed nose and large webbed forefeet that are clawed. Hind feet are smaller and narrow with sharp claws. Size will vary between species and also within species because of environments being more arid or moist. Average weight is 4 oz., 6 inches upto 12 inches in length, with smooth dark pelt and tail sparsely covered.

Physical: Can fix oxygen found in tunnel environments that offer low concentrations of oxygen and higher carbon dioxide levels through high hemoglobin levels in their blood. Digging and excavation tasks are enabled by superb muscular structure of mole. Cellular structures on nose, belly and tail provide for an extremely highly tuned sense of feel, which enables them to locate food rapidly, sense tunnel air pressure changes, remember tunnel routes, and respond to intrusion from many sources.

Activity Periods: Works throughout year, typical 3 periods of daily work intensity. Slows down during extremes in weather and relies on stored food supplies in deep nesting tunnel systems.

Social Structure: Colonial during weaning. Broad home range. Typically territorial or solitary. Overlapping runways but generally never share home range systems. Will share common thoroughfare system in historically infested areas. Avoid each other unless during highly charged breeding cycle and weaning process.

Habitat: Live in seclusion in underground tunnel systems,Only social when breeding. Systems are typically made up of shallow feeding tunnels that run downward into deep nesting tunnel systems that can be few feet underneath the shallow systems. Upper systems can leave heaved turf. Infested areas will have above ground conical shaped mounds created by the excavated tunnel soil and debris. Mounds seem to follow a line, unlike a gopher's random mounding pattern and crescent shaped mounds. Spend about half their time sleeping in their deep tunnel system nests.

Food: Although moles are typically referred to as an insectivore, they are more of an omnivore. They eat methodically on earthworms and soft-bodied insects but will consume vegetative matter as well as other rodents and even birds. A mole will consume 70-100% of its body weight based on the derived calories from the target of their feeding (Endothermic exchange). Since worms offer so little calories per serving, they are forced to consume masses of them to survive. Moles will also clip the worm's head off and roll the remainder up in a deep food storage vault for later consumption, generally when temperature and soil conditions limit high energy.

Abundance: Typically can find 3-6 per acre in a large population. Populations generally vary with soil and food conditions. Territories will overlap and can be almost 20 times the area of a pocket gopher home range. Prefer lighter more friable soils with corresponding benefit of good gas exchange and higher population of target foods.

Breeding Season: January through April. Breeding follows improved food and temperature conditions. Males will construct and maintain overlapping systems to adjoining female tunnel systems during this cycle. Males will build large radial systems to overlap female home ranges. Gestation: Between 30-42 days. She continues to forage and build nests. Less digging activity.

Litter Size: 3-6 young. Field (natural) mortality varies but can reach 50%+ over the first year.

Weaning: 4-5 weeks. Female will forcibly disperse young to adjoining or distant areas. Juveniles will travel up to a 1/4 miles. Mole can reach adult size within several months. The male assists in tunnel maintenance, food gathering and nest maintenance and leaves the female when juveniles are gone.

Predation: Badgers, hawks, owls, domestic pets, and weasels. All typically have little effect on general mole population, unless the mole is above ground foraging or moving to another site to burrow.

What Mole Looks Like

There are several kinds of moles in the US. The most widely distributed one is the Eastern mole whose range extends west as far as central Texas and overlaps the range of the hairy-tailed and starnose moles. California has its own mole.

Eastern moles spend most of their lives underground, feeding on earthworms and the larvae and adults of many kinds of insects. Depending on their sex and age, they vary in size from 4 to 9 inches long. Their low-slung, streamlined bodies are covered by a thick, velvety fur which is gray to blue-gray. Their large thick-clawed forepaws are their digging tools. Although moles have very poor eyesight, they have excellent hearing and sense of smell. They also are extremely sensitive to vibrations, which they detect through nerve endings in their snouts and their tails. They hold their tails erect during tunneling to monitor any overhead vibrations.

Moles make two kinds of tunnels. Their warm weather surface tunnels are 1½ to 4 inches below the soil surface when insects and worms are near the surface and causing the most damage to plants in the yard. Some shallow tunneling is also from the male mole’s search for a mate. Cool weather tunnels 4 to 40 inches deep help them find insects and worms that have moved farther underground to escape frost. Moles never hibernate, so they must find food there. Mole’s Feeding Habits Moles are active 24 hours a day. Because they digest a complete meal roughly every 4 hours, they eat for 4 hours, then sleep the next 4 hours, and so on. They have specialized teeth--large pointed incisors--which are ideal for helping them catch and eat soft-bodied soil dwellers such as worms and grubs. Because of these teeth moles cannot chew and eat poisoned peanuts, gobs of chewing gum, and the multitude of hard objects that are often suggested as baits. Also, moles are carnivores. They prefer mostly insects, grubs, centipedes, spiders, and earthworms they find in the soil. Stomach content studies reveal that most moles eat only small amounts of vegetable matter. They consume 70% to 100% of their own weight each day and, thus require large amounts of food. As soon as the supply of bugs and worms disappears from a yard, moles move on to new territories. Distinguishing The Mole From Other Similar Animals

Moles may be distinguished from meadow voles, gophers, and shrews by their naked, pointed nose that extends well in front of the mouth. Small eyes and ears are concealed by fur. Their spade like forefeet are wider than they are long. Discharged mounded soil and heaved runways are indicators of this pest's presence.

Mole tunnels differ from gopher tunnels in one critical way. Moles push a short shaft straight up to the surface from their tunnels. As they push soil out through this hole, it forms a nearly circular mound, often with "ripple marks" or concentric circles marking layers of deposited dirt. Gophers, on the other hand, construct a short inclined tunnel to the surface, and as they push the dirt out, they pile it only on one side of the hole. This offset soil mound is a helpful distinction in identifying gophers. They are more serious pests than moles.

Moles are much maligned, delicate creatures that improve the soil, eat many pest insects, and get blamed for damage they do not cause. At one time, they were prized for their velvety fur, and a farmer angered by mole activity could count on being able to sell the pelt for a good price. Although moleskin is no longer in vogue, killing moles is still popular. A better strategy is to try to tolerate them. In the long run, they are beneficial to the garden.

Moles eat many pestiferous beetle larvae, or grubs, and other insects, though they may also eat earthworms and centipedes and occasionally a small amount of vegetable matter, especially if it has been softened by water. The Townsend mole, found in the Northwest, eats more vegetation than do the other common mole species (there are seven in the U.S.), but a mole will starve to death if offered only plant food.

Gardeners most often object to the sight of mole tunnels or mole hills, perhaps fearing permanent damage to plant roots. In fact, the only real damage caused by moles is indirect, a result of their shallow tunnels lifting the soil and allowing plant roots to dry out. The best immediate response is to press back the soil with your foot and to water the area thoroughly to keep the roots moist as they re-anchor themselves in the soil.

Mole runways may be used by rodents such as voles, white-footed mice, and common house mice, which eat seeds, bulbs, and roots, and do cause direct damage to the garden and home fruit orchard. But these vegetarians generally have small home ranges, and a mole rarely stays in the same area for any length of time. Once it has eaten the local soil insects, it moves on.

If placed on the soil surface, a mole can dig out of sight in 10 seconds and will tunnel at the rate of 1 foot in 3 minutes. It can run through established tunnels at about 80 feet per minute. A mole spends about half its life searching for food in its underground tunnels, any time of day or night; it consumes about 40 pounds of insects in a year.

The mole’s body shows many adaptations to a life lived in narrow tunnels underground: a streamlined skeleton 5 to 7 inches long, fur that can point forward as easily as aft, a narrow snout, no external ears, small eyes covered with skin, and outwardly pointing claws and feet.

Its stout front claws are the mole’s only means of digging through the soil. The mole uses them alternately to push the soil away from its face and along the sides of its body. A rodent’s feet, by contrast, can be used to dig like a dog. Since they can be placed flat against the ground when walking or running, the rodent is as agile above ground as below. Not so the mole, who shows off its unique adaptations best when “swimming” through soft, moist earth

Although rodent skulls are comparatively tough, the mole’s skull is delicate. The mole cannot use its head in digging, thus its preference for soft, loose, moist soil. In fact, its head is so fragile and sensitive to vibrations that a mole can easily be stunned or even killed by the slap of a shovel over a tunnel where it is active.

Although its eyes are almost useless, probably helping the mole to distinguish little more than light from dark, its hidden ears are remarkable in their acuity, making it possible for the mole to locate its prey through many inches of earth. Its sense of smell is also excellent.

Two kinds of tunnels

A mole builds two types of tunnels. Its permanent tunnels may be quite deep and undetectable from the surface. Its nest, located in these permanent tunnels, may be 1 to 2 feet deep. Within these tunnels, the mole will be active year-round. It is its shallow feeding runways, sometimes used only once, that are of concern to gardeners.

If you are faced with an elaborate series of tunnels, it probably does not mean you have more than one mole, just a very active runway builder. Most species of moles are not gregarious. In fact, they are highly territorial and will fight to the death other moles attempting to enter their own burrow system.

Anatomy of a mole tunnel

You’ll rarely detect a mole’s permanent tunnels, built a foot or more underground and leading to a nest that can be 2 feet deep. The familiar molehills are feeding runways, excavated close to the surface. What appears to be the work of many moles is more likely the industrious efforts of just one. A runway may be used only once, and a hungry mole can build an extravagant number of them in search of grubs and other insects.

Mounds created by moles can be distinguished from those of the gopher by their shape, and by the texture of the soil used to build them. Mole hills are built like a volcano; the earth clumps thrown out through the center roll down on all sides. Gopher mounds may contain coarse dirt and form a half circle. The exit hole is on one side, and the earth is pushed away from it in a three-quarter moon shape.

Create a mole barrier

Borders of stone-filled and/or compacted soil will discourage moles, because they cannot dig in such soil. The barrier must extend at least 2 feet into the ground. If the stony or compacted barrier is paved over, you can simultaneously create a mow-strip, walkway, and mole deterrent.

Another approach is to install a fence of 1⁄4-inch hardware cloth extending 18 inches under and 10 inches above ground. At its base underground, if the wire is bent in an L- shape pointing away from the area to be protected, it will also exclude gophers and rats. Extended 24 inches above ground, it will keep out rabbits, too.

Established fruit trees will benefit from the soil aeration accomplished by moles, but very young, newly planted fruit trees can be disturbed by the burrowing. Protect new trees by circling the root ball with a 1⁄2-inch hardware cloth cage. Overlap the ends of the wire mesh a couple of inches so the cage is temporarily closed to rodents, but leave the nds unsecured so the roots can gradually force the cage apart as the tree grows. Extend the wire mesh a foot above ground, creasing and pressing it closely around the trunk of the tree, to protect against mice as well. By the time the cage is no longer necessary underground, it will have rusted away.

Capture moles for relocation

Lethal, scissor-jawed mole traps do their job well and are easy enough to set, but we think a mole you insist on removing should be captured live and relocated.

Spring flooding, where it occurs in low-lying areas or streamsides, is a natural control of mole populations. The adults may manage to climb out of their tunnels to an elevated ridge or mass of drifting materials while they wait for the water to subside, but the young are extremely vulnerable in their nests, and even heavy rains have been known to drown them. Water can be similarly used to help relocate a mole you’ve deemed errant. It is likely to be most effective if used against West Coast moles that betray their deeper nests by throwing up large mole hills. Open the mole hill, poke a hose into the tunnel, and turn on the water. You can expect it to take a little while before there is enough water in the tunnels to flush the mole. Watch for the mole’s emergence from one of its other exits. Scoop it up with a shovel and relocate it outside the garden.

Moles can also be captured live in a pit trap, then released away from the garden. Determine which is an active runway by pressing down the tunnels and looking for one that is reopened. Open that tunnel and bury a large-mouth jar or coffee can in the path of the mole and cave in the runway just in front of the jar on both sides. Then cover the top of the disturbed section of the tunnel securely with a board. No light should penetrate the tunnel where the trap has been placed. A mole will not be able to climb out of a 3-pound coffee can.

If you have not caught the mole after two days, it probably means the mole is no longer working over that area or that you disturbed the area too much in setting the pit trap. Move the coffee can to a new location. Better yet, recycle the can and give the poor mole a break.