What animals eat tree bark?

Who is Stripping the Bark From My Trees?

By Chris Williams on March 29, 2016.

Gray squirrel gathering cedar bark for its nest

Occasionally we visit a property where something has been pulling bark off of trees. The owners are of course concerned that their trees will die and they demand to know who is responsible.

The Possible Culprits

There are a number of animals that sometimes remove bark from trees, ranging from black bears, to porcupines, beavers, rabbits, and squirrels. Deer can remove bark with their antlers during rutting season. Beavers and rabbits don’t climb so can only strip bark as high as they can reach. Voles and deer mice sometimes chew on the trunks of trees in winter, especially low, below the snow line (see Preventing Winter Lawn Damage From Voles).

In our region though, squirrels are the main culprits when bark is stripped from trees in residential yards. Fox squirrels are more likely to strip tree bark, although gray squirrels and red squirrels can cause the damage as well. Fox squirrels look like a cross between gray squirrels and red squirrels but they are larger than either one.

Squirrels Will Strip Bark and Clip Twigs

Squirrels tend to strip bark in late winter. They seem to prefer deciduous trees with a smooth bark but dozens of different trees are reported to have been damaged by squirrel strippers. The stripped areas usually measures ½ inch wide and 3 to 6 inches long and is usually on a horizontal branch rather than on the trunk. Trees can generally survive some stripping damage but if the trunk is girdled by more than 50%, the tree may die.

Squirrels also clip twigs in spring (for nest building) and early fall (to reach nuts or cones). Twigs or small branches that are 1/4 to ½ inch in diameter are sometimes clipped and dropped to the ground.

Why Do Squirrels Strip Bark?

No one is sure why squirrels remove bark but there are several possible reasons:

  1. Collecting soft material to use in nest building.
  2. Looking for food or additional nutrients in bark. For example, red squirrels like to clip branches of maples to get to the sweet sap.
  3. Pregnant females may strip bark prior to giving birth as a distraction from the pain.
  4. Just because they can and because they like to do it. Squirrels like to gnaw and for bored squirrels, stripping bark might be like popping bubble wrap for people.

If you have one or two squirrels or another animal that is damaging your trees, give Colonial Pest a call. We humanely trap and remove nuisance wildlife.

Photo Credit : lucycat | ©

What to Do If Squirrels Are Chewing the Bark off Your Trees

Squirrels are known for their habit of chewing on things, including the bark on trees. They usually chew on trees that have thin bark because it is easier to chew than thicker bark. Squirrels use bark in their nests. When bark is removed from trees, the cambium layer with sugars and nutrients is exposed. Squirrels often eat that layer when other food is scarce, particularly in the winter. Chewing on bark can also maintain the health of a squirrel’s teeth.

How a Squirrel’s Chewing Can Affect Trees

A tree can survive if a squirrel chews off a relatively small patch of bark, but if too much is removed the tree can die. If a squirrel chews the bark off a tree in the summer, insects and fungi can damage the tree. If all of the bark is removed from a limb, the limb needs to be cut off before it dies and falls. A dead tree limb can cause property damage or injuries to people.

What to Do If Squirrels Are Chewing Your Trees

If squirrels in your yard have been chewing the bark off your trees, there are some steps you can take to save your trees. You can wrap pieces of flashing at least 2 feet wide around the trunks of the trees with the top at least 5 feet above the ground. This will not work if the squirrels can jump from another tree or structure to a tree.

When to Have Squirrels Removed

If putting flashing around tree trunks does not work, or if the trees are too close to your house and squirrels can easily jump onto them, you will need to try another strategy. You can have the squirrels in your yard trapped and relocated. You should not try to do this yourself because you could be bitten or scratched.

Call Anderson Wildlife Control. We will trap the squirrels in your yard and relocate them to another place to prevent further damage to your trees. We use environmentally friendly methods and never harm any of the animals we capture. Call Anderson Wildlife Control today to get an estimate for squirrel removal in Connecticut.

I planted a small tree in early June and animals began chewing on the bark in late June. I know that tree wrap is normally used in the winter, but is it safe to use it in the summer? I don’t want to cause disease problems on the bark.

Rather than using paper tree wrap, try the plastic coiled wrap that is flexible and perforated to allow air circulation. It comes in assorted diameters as well, so you can custom fit it to the current caliper of your tree and allow room for growth. Reputable nursery and garden supply centers carry this product. Nursery stock trees will often already have this flexible coil around the trunk. You only need it about two feet up from the base, which is about the height a rabbit can stretch.

Young deer will sometimes sample bark to see if it’s tasty. But they really prefer new leaf and flower buds. If you have evidence of deer, such as droppings or hoof prints, you may have to resort to spray products such as Deer Off. It is a citrus and peppermint-based spray, which lasts about two to three months. It does not wash off in rain or irrigation cycles. It clings without deforming or adulterating the plant by using vegetable oil as its agent. Deer have much better noses than we do, and they find the peppermint scent and taste unpalatable.

Meadow mice (voles) and rabbits, however, are generally the culprits for chewed bark. Occasionally juvenile groundhogs will also sample young tree bark. (A bit like human babies putting everything in their mouth to get the taste and texture.) Young trees are more succulent and desirable as creatures forage for food for themselves and their broods.

If there are raised tunnels in the vicinity of your tree, then more likely you are dealing with voles. Place three or four simple plastic snap mousetraps baited with a dab of peanut butter around the base of the tree. Check the traps each morning for a week. If the traps are sprung, remove any remains and re-bait them. If done consistently, you may eliminate the entire offending colony within that period. The perforated plastic tree wrap will also deter the rabbits and frustrate the groundhogs. Using both methods should protect your tree from additional damage.

Hi everyone,I will give you in this subject: the answers of CodyCross Rodent responsible for tree planting. This game developed Fanatee Games, contains many puzzles. This is the English version of the game. We must find words in the crosswords using the clue.The game contains different levels of challenge that require a good general knowledge of these topics : politics, literature, mathematics, science, history and various other categories of general culture. We have found the answers at this level and share them with you to help you continue your progress in the game without any difficulty.If you are looking for answers, then you are in the right subject.The game is divided into different worlds, then in a group of puzzles, the answer is proposed according to the order of appearance of the puzzles.

CodyCross Rodent responsible for tree planting:

You can also control the game by following the main dedicated topic :

Cheats for Codycross


You can then find the answer of the following clue here : CodyCross __ Bogart, famous for film noir such as Casablanca.

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Rodent Responsible For Tree Planting – Culinary Arts CodyCross Answers

CodyCross, Crossword Puzzles is first released in March 2017. In the same year CodyCross won the “Best of 2017 Google Play store”. I just opened the Google Play Link of this game and found that until now (April 2019) this game has more than 10.000.000 installations. This is huge and this game can break every record. CodyCross is developed by Fanatee, Inc and can be played in 6 languages: Deutsch, English, Espanol, Francais, Italiano and Portugues. We have posted here the solutions of English version and soon will start solving other language puzzles. The game consists on solving crosswords while exploring different sceneries. Solving every clue and completing the puzzle will reveal the secret word. In more simple words you can have fun while testing your knowledge in different fields. So here we have solved and posted the solution of: Rodent Responsible For Tree Planting from Puzzle 4 Group 126 from Culinary Arts CodyCross. Question is: Rodent Responsible For Tree Planting and answer is: Squirrel. On the application type: SQUIRREL

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By Joan Allen for UConn Extension

Photo: Meadow vole damage. Credit: Robert L. Anderson, USDA Forest Service, Bugwood.org

A lot of snow cover during the winter can be both good and bad. Good because it’s beautiful and nice for winter sports. It also insulates overwintering perennial roots from temperature fluctuations and extremes. One of the negative impacts is that the snow provides cover for the activity of voles. These small mouse-like rodents feed on the bark of roots or lower trunks of woody plants during the winter and they are likely to feed where protected by shelter, including snow.

As the snow melts in the spring, look for tunnel-like tracks in lawns and gardens that are telltale signs of their activity in the area. If plants that were healthy last season are weak or fail to leaf out completely this year, look for evidence of vole damage as shown in the photos.

Two voles species are common in our area, the pine vole and the meadow vole. Pine voles feed primarily on the roots below ground while meadow voles prefer to feed on bark above the soil line. More information on vole damage and control is available in this Cornell University fact sheet.

Colorado State University

Print this fact sheet

by W.F. Andelt, S. Ahmed and K. Jones* (11/15)

Quick Facts…

  • Eight species of voles are found in Colorado. They often are called meadow, field or pine mice.
  • Voles are small mammals that cause damage by girdling seedling and mature trees in orchards, shelterbelts and forests. They also damage field crops and frequently construct runways in lawns.
  • Damage by voles can be reduced by habitat modification, exclusion, repellents, trapping, and poison grain baits.


Voles are small rodents that measure 4 to 8.5 inches long and weigh 0.8 to 3 ounces and vary in color from brown to gray. They are pudgy, with blunt faces and small eyes, small and sometimes inconspicuous ears, short legs, and a short (the long-tailed vole is an exception) and scantily haired tail.

Eight species of voles are found widely throughout various ecosystems of Colorado, in heavy ground cover of grasses, grass-like plants, and litter.

Southern red-backed voles (Myodes gapperi) are found in moist and well-developed coniferous forests. They are most abundant in lodgepole pine (Pinus contorta) stands, usually between 8,000 and 11,000 feet.

Figure 1: Southern red-backed vole distribution.3

Meadow voles (Microtus pennsylvanicus) primarily occur from north to south central Colorado and along the South Platte River. They tend to live in or near damp marshy areas or wet meadows and riparian corridors.

Figure 2: Meadow vole distribution.3

Montane voles (Microtus montanus) primarily are found in the western half of Colorado in moist meadows and valleys with thick grass or forb cover from 6,000 feet to above timberline.

Figure 3: Montane vole distribution.3

Long-tailed voles (Microtus longicaudus) are common over the mountains and high plateaus of the western half of Colorado. They are most abundant in streamside meadows in marshy to dry grassy areas.

Figure 4: Long-tailed vole distribution.3

Mogollon voles (Microtus mogollonensis)are found in the very southern part of Colorado, in Las Animas and Montezuma Counties. They occur in ponderosa pine (Pinus ponderosa) woodland or savannah, pinon (Pinus edulis Engelm)–juniper (Juniperus monosperma and Juniperus scopulorum) woodlands or montane shrublands.

Figure 5: Mogollon vole distribution.3

Prairie voles (Microtus ochrogaster) are found in grasslands and along streams and irrigated lands in eastern Colorado.

Figure 6: Prairie vole distribution.3

Sagebrush voles (Lemmiscus curtatus) occupy the driest of all vole habitats in Colorado. Often found in sagebrush habitat, they occur between 5,000 and 9,000 feet in western and north central Colorado.

Figure 7: Sagebrush vole distribution.3

Western heather voles (Phenacomys intermedius) are found from 7,000 to above treeline of central Colorado. They occupy a variety of habitats but are most abundant along streams.

Figure 8: Western heather vole distribution.3

Voles eat a variety of grasses, forbs and agricultural and garden crops. They also eat bark on trees and shrubs, especially during fall and winter. While they prefer young, succulent trees and plants, they can change their diet to meet their nutritional needs.

Biology, Reproduction and Behavior

Voles are active day and night throughout the year and do not hibernate. They usually live between two and six months. Their home ranges usually are less than one-fourth acre and vary with season, food supply and population density. Voles construct many surface runways and underground tunnels with numerous burrow entrances. A single burrow may contain several adults and young.

Population densities of voles vary from species to species. Large population fluctuations that range from 14 to 500 voles per acre are common. Their numbers generally peak every three to five years. Population is influenced by dispersal, food quality, climate, predation, physiological stress, and genetics.

Voles have three to six young per litter and three to 12 litters per year. Their gestation period ranges from 20 to 23 days and they breed almost year around, although most reproduction occurs in spring, summer and fall. Females may become pregnant at three weeks of age.

Ecological Value

Voles, like many small rodents, are an important food source for many predators. A variety of predators feed on voles including coyotes, foxes, bobcats, weasels, snakes and several species of owls and hawks. Caution must be taken when using rodenticides. Zinc phosphide, a restricted use pesticide, is one control method for voles, however, it is extremely toxic and care must be taken to avoid risks to children, pets, and non-target wildlife species. Carefully read and follow the label for any rodenticide.

Damage and Control

Voles can cause extensive damage to forests, orchards and ornamental plants by girdling trees and shrubs. They prefer the bark of young trees but will attack any tree, regardless of age, when food is scarce. Monitor orchards frequently so control measures can be implemented before appreciable damage occurs. Most damage occurs in the winter when voles move through their grass runways under the protection of snow. The greatest damage seems to coincide with years of heavy snowfall.

Damage to crops, such as alfalfa, pasture grasses, clover, potatoes, carrots, beets and turnips is common and most evident when voles are at high population levels. Runways and tunnel systems constructed in agricultural fields can divert irrigation water. Voles often damage lawns and golf courses by constructing runways and burrow systems.

Vole damage to trees and shrubs is characterized by girdling and patches of irregular patterns of gnaw marks about 1/16 to 1/8-inch wide. Gnawed stems may have a pointed tip. Do not confuse vole damage with damage by rabbits, which includes stems clipped at a smooth 45-degree angle and wider gnaw marks. Stems browsed by deer usually have a rough jagged edge. Voles also girdle the roots of trees and shrubs.

Other signs of damage by voles include 1) 1 to 2 inch-wide runways through matted grass and burrows; 2) visual sightings; 3) hawks circling overhead and diving into fields; and 4) spongy soil from burrowing activity. Trees that appear to suffer from disease or insect infestation may be suffering from unseen vole damage.

Figure 9: Vole damage on lilac. Notice small, irregular tooth marks, all under what was the snow line.
Figure 10: Vole runways in lawn after snow melted in spring.
Figure 11: Vole hole and runway in clay soil.
Figure 12: Vole hole and runway in snow. Note the oval-shaped OPEN hole.
Figure 13: Examples of vole holes. They will often burrow near a rock, but not always.
Figure 14: Examples of vole holes. They will often burrow near a rock, but not always.

Methods to prevent and control damage are: habitat modification, exclusion, repellents, trapping, and poison grain baits. Voles are classified as non-game wildlife in Colorado and may be captured or killed when they create a nuisance or cause property damage.

Habitat Modification

High vole populations cannot become established without food and lack of predation by predators. Elimination of weed ground cover and tall grasses by frequent and close mowing, tilling, or herbicide application is the most successful and longest lasting method to reduce vole damage to orchards. This will diminish the amount of available habitat and reduce their numbers. Prunings left in orchards prevent proper mowing and provide a temporary food source, which may lead to damage by voles. Planting short grasses that do not mat or lodge, such as buffalo grass, blue grama, or dwarf fescues, will provide little protective cover and may reduce vole numbers.

Meadow voles are active during the day within their runways under thick grass and vegetation. Summer removal of vegetation (2 feet radius around fruit tree trunks) provides some protection because voles avoid exposed areas.

Damage to lawns can be reduced by close mowing in the fall before snow arrives and by mowing and removing tall grassy cover near lawns. To repair damage to lawns from runway construction, rake, fertilize and water the affected area. Close mowing and weed management in grassy borders adjacent to agricultural crops will reduce the habitat for voles and should reduce damage. If suitable, plant crown vetch (a legume unpalatable to voles) in orchard and field boundaries to reduce vole populations.


To protect against vole damage, encircle young trees and shrubs with 1/4-inch mesh hardware cloth or 3-inch diameter Vexar™ plastic-mesh cylinders. This barrier should project 18 inches above the ground and 3 to 6 inches below the surface. Vegetable and flower beds may also be protected in this manner.


Only a few repellents (including Thiram™ and Hot Sauce or capsaicin) are manufactured to protect trees, shrubs and vegetable crops from voles. Little data are available on the effectiveness of repellents to deter vole damage. However, in one study, Thiram™ was reported to reduce damage to apple stems by 78 percent. A 20 percent solution of chicken eggs in water has been effective in reducing deer and elk browsing and may reduce damage by voles.

Thiram™ is manufactured by various companies and sold under various trade names. Thiram™ products are labeled for protecting most of the following from voles: tree seedlings, shrubs, ornamental plantings, nursery stock, and fruit trees. Most labels limit the use of Thiram™ on fruit trees to the dormant season.

Capsaicin (the “heat” in spicy peppers) is labeled for use on ornamental trees and shrubs, fruit and nut trees, fruit bushes and vines, and nursery stock to protect them from vole damage. Limit application to fruit-bearing plants before fruit sets or after the fruit is harvested. Hot sauce also is registered for use on beans, corn, cucumbers, melons, peas, brussel sprouts, squash, peppers, tomatoes, cabbage, and cauliflower before edible portions and/or heads begin to form. Capsaicin may burn the leaves on plants. Spray a few leaves first and check for damage before spraying the whole plant.

Another product that is available that is labeled for voles is Ricinis communis oil (Castor Oil). Though its effectiveness is not known, it is labeled as safe around children and pets.

Predator odors, such as the urine from red foxes and coyotes, also may be effective vole repellents. These odors are not commercially manufactured, but fox and coyote urines can be purchased from some trapper supply houses.

Repellents are relatively expensive and provide short-term protection. They may wash off during rain and must be reapplied periodically.


Use mouse snap traps to remove small populations of voles from backyard lawns. Place traps perpendicular to runways with the trigger end in the runway and bait with small amounts of rolled oats or peanut butter. Set traps in the fall before most damage occurs. Trapping is not practical for controlling voles in large areas or on large populations.

Rodenticide Safety

When dealing with any rodent problem, utilize all management techniques to resolve the problem and do not rely solely on rodenticides. Set realistic goals such as minimizing the rodent number on your property by using exclusion methods, eliminating desirable habitat or food sources (you’ll never eliminate all voles). When using any rodenticide always read and follow the label and guidelines and be sure you understand them prior to use to minimize off target (i.e. raptors, dogs, and cats) poisoning. Rodenticides are meant to kill rodent species but will also kill other species if improperly used.

  • Positively identify the pest and determine all techniques that can be used to deter the pest such as habitat modification and exclusion
  • Decide what your threshold limit is. Set realistic goals such as minimizing rodent numbers. Do not expect to totally eliminate them
  • Choose the most effective, least toxic rodenticide
  • If you choose to use a rodenticide,
    • Read and follow the label
    • Abide by any limitation of use (i.e. use only between Nov. 1 and March 30) and other label restrictions
    • Wear proper protective clothing and equipment
    • Don’t smoke or eat while mixing, applying a rodenticide, and wash thoroughly after application
    • Mix and apply only the quantity you need
    • Reference: EPA Citizen’s Guide to Pesticide Safety
    • Always store rodenticides away from pets, children and wildlife
    • Always locate rodenticides so that off target species cannot access them (i.e. children, pets, wildlife). Use enclosed bait boxes, make sure rodenticide is deposited deep enough in the tunnel or locate them in locked areas inaccessible to children, pets or wildlife
    • Never store rodenticides near food items (human, pet or livestock)
    • Follow the label instructions on carcass surveillance

Poison Grain Baits.

Rodenticides usually are a short-term solution to damage by voles. Habitat modification usually is more successful than rodenticides for eliminating damage in orchards.

Two percent zinc phosphide is the most commonly used grain bait for managing voles in Colorado. Zinc phosphide is extremely toxic and care must be taken to avoid risks to children, pets and non-target wildlife. Zinc phosphide baits are available in pellet form (Bell Laboratories’ ZP Rodent Bait AG, Chempar’s Ridall Zinc) on oats (Bell Laboratories’ ZP Rodent Bait AG, USDA/APHIS/ADC Zinc Phosphide on steam-rolled oats) and on corn (Hopkin’s Zinc Phosphide Bait). One study indicated that pelleted zinc phosphide baits provide greater control of voles than zinc phosphide placed on oats or corn. Most of these baits are labeled for use in orchards and groves, nurseries, ornamental and non-bearing fruit trees, grapevine yards, and non-crop areas such as lawns, ornamentals, golf courses, and parks. The labeled method of application varies somewhat among manufacturers.

However, most of these products are labeled for hand baiting, broadcast baiting, and/or trailbuilder baiting in orchards and groves, nurseries, and ornamental and non-bearing fruit trees. In grapevine yards, these products are labeled for broadcast baiting. The Chempar product also is labeled for hand baiting. In non-crop areas, these products are labeled for hand baiting in conjunction with a prebait.

To prebait, scatter 4 or 6 pounds (see label instructions) of untreated oat groats, rolled oats or barley (see label instructions) per acre, two to four days before placing a toxic bait. Prebaiting encourages consistent acceptance of bait.

When hand baiting around trees, place 1 teaspoon (4 grams) of bait at two to four locations around each tree in surface trails or at the mouth of holes leading to underground burrow systems. In non-crop areas, hand baiting generally consists of placing 1 teaspoon of bait around each active burrow or runway. The most successful control is achieved when the bait penetrates the grass cover to reach the runways. To broadcast bait, spread 4 to 10 pounds of bait per acre with a cyclone seeder or by hand. Bait also can be spread with a trailbuilder. A trailbuilder usually is pulled by a tractor, creates a burrow in the ground and deposits 1 teaspoon of bait at 4 to 5 feet intervals. Two to 3 pounds of bait per acre usually is recommended.

Zinc phosphide baits are limited for use only on voles of the genus Microtus. Some of the zinc phosphide products and/or usages are limited to meadow voles.

To minimize hazards to birds, do not apply zinc phosphide bait to bare ground, areas without vegetation, or in piles. Also, do not apply to crops destined for use as food or feed. Zinc phosphide can be applied to orchards and groves only during the dormant season after harvest.

The best time of year to use zinc phosphide baits on lawns is during fall before snow cover. Application of bait during spring, after snow melt, usually is ineffective.

Unpredictable rain and snowfall will severely limit the lifespan of baits exposed on orchard floors. During wet periods, place baits in jars, metal cans, bait stations, polyvinyl-chloride tubes, or under tar paper, shingles, and split automobile tires. Unfortunately, baits placed under these objects and directly on the ground absorb moisture and generally do not persist more than two weeks.

Because zinc phosphide is toxic to animals, store it away from humans and pets. Zinc phosphide can be absorbed in small amounts through human skin. Wear rubber gloves to avoid contact with the chemical and take extra care to avoid breathing zinc phosphide dust. Product labels will contain additional precautions. Always read and follow the product label.

Anticoagulant baits (warfarin and bromadilone) can also be effective in managing voles. For anticoagulants to be effective, it may take multiple applications. Anticoagulants are slower acting agents and take 5 – 15 days to affect voles. As with zinc phosphide, place the baits in secure
bait boxes to reduce accidental and secondary poisoning. Always read and follow the product label.

Fumigants usually do not work for control of voles because their burrows are too shallow and complex.

3 Distribution Maps: Armstrong, David M., James P. Fitzgerald, and Carron A. Meaney. 2011. Mammals of Colorado 2nd ed. Colorado: Denver Museum of Nature & Science and University Press of Colorado.

*W.F. Andelt, Colorado State University Extension professor emeritus, department of fish, wildlife and conservation biology; S. Ahmed, former graduate student; fishery and wildlife biology. Reviewed by K. Jones, Extension County Director, (4-H/Natural Resources/Agriculture) Chaffee/Park County. Revised by S. Bokan, Small Acreage Coordinator Boulder County, K. Crumbaker, Ag and Natural Resources Agent Larimer County, T. Hoesli, Extension County Director Grand County, D. Lester, Extension County Director, Park County and I. Shonle, Extension County Director Gilpin County. 2/03. Revised 11/15.

Colorado State University, U.S. Department of Agriculture and Colorado counties cooperating. Extension programs are available to all without discrimination. No endorsement of products mentioned is intended nor is criticism implied of products not mentioned.

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Since the first publication of this article on vole damage in citrus, a recent field observation regarding vole activity is worth noting. Voles prefer a situation where there is cover and shelter generally from weed or grass. In some orchards established in the last few years a plastic strip has been installed along the tree row for weed management (Fig 1). These strips appear to be offering a sheltered environment for vole activity in some cases (Fig 2). Recent observations in two such installations, one a block planted in 2013 and the other an eight year old planting exhibited significant vole activity. The young orchard at this point does not exhibit obvious tree damage although active tunneling is apparent (Fig 3). In the older orchard feeding damage to the trunks is very obvious (Fig 4).

Meadow Mice (Voles) can cause serious damage in a citrus orchard resulting in partial or complete girdling of a tree (Fig 5). Trees often exhibit damage to the bark of the tree from the soil line up 6-8 inches (Fig. 6 ). On close inspection, an open hole 1-1.5 inches in diameter may be found at the base of the tree (Fig 7).

Five species belonging to the genus Microtus are found in California, two of which “Microtus californicus” and “M.montanus” are reported to cause damage. Damage has been reported in permanent pasture, alfalfa, hay, artichokes, Brussels sprouts, carrots, cauliflower, potatoes, sugar beets, tomatoes, grains, nursery stock and the bark of apple, avocado, citrus, cherry and olive trees.

Microtus are often found where there is grass cover. They generally do not invade cultivated crops until the crop is tall enough to provide food and shelter. Meadow mice are active all year round. They forage at any time during the day or night but are chiefly nocturnal. They are usually found in colonies marked by numerous 2– inch wide surface runways though matted grass. Small brownish fecal pellets and short pieces of grass stems along the runways are evidence of activity. The burrows consist of extensive underground tunnels, nest chambers and storage chambers. Home range is typically small, less than a 60 foot radius in the case of “M.californicus”. All meadow mice swim well. Therefore, irrigation ditches will not serve as effective barriers against meadow mice movement into fields. Meadow mice may forage beyond the sheltered runways. Food consists of tubers, roots, seeds, grain, and succulent stems and leaves.

Females breed at 4 to 6 weeks of age with litter size of “M.californicus” averaging around 4. Under natural conditions a female Microtus may produce from 5 to 10 litters a year. The major breeding season corresponds with the season of forage growth. Microtus populations build up to a peak every 3 to 4 years, followed by a rapid decline during the next breeding season. The exact causes of the cycle of buildup and decline are not known, though disease, food shortages, physiological stress from overcrowding, and other factors may be involved. It is assumed that in cultivated areas Microtus populations are permanently based in favorable habitat such as roadsides, canal banks or adjacent noncultivated land. Invasion of cultivated cropland occurs when the population builds up or when the wild habitat becomes unfavorable. Coyotes, badgers, weasels, snakes, hawks, owls, herons and gulls are among the principal predators. It is believed that predators are not able to prevent or control a population eruption because of the birth rate of the fast breeding Microtus population. Meadow mice are classified as nongame mammals by the California Fish and Game Code. Nongame mammals, which are found to be injuring growing crops may be taken at any time or in any manner by the owner/management. The most effective management options in an orchard situation are a reduction in ground cover and the use of toxic baits. Meadow mice are cover dependent. In situations where cover removal is not possible or is insufficient to solve the problem, the next best option is the use of toxic baits. Many bait carriers are used (e.g., oat groats, wheat bait). Baits: Crimped oat groats are the most satisfactory bait although crimped whole oats are used (e.g., oat groats, wheat grains, pelletized formulations, etc., but crimped oat groats have typically been most effective). The primary toxicants used for meadow mouse control include zinc phosphide, diphacinone, and chlorophacinone. Directions for management including baiting can be obtained by contacting the Agricultural Commissioner’s Office. * Portions taken from J.P.Clark Vertebrate Pest Control

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