Quick viewing(Text Mode)

Tree Squirrels

Tree Squirrels

University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln

The Handbook: Prevention and Control of Wildlife Damage Management, Internet Center Wildlife Damage for

July 1994

Tree

Jeffrey J. Jackson University of Georgia

Follow this and additional works at: https://digitalcommons.unl.edu/icwdmhandbook

Part of the Environmental Sciences Commons

Jackson, Jeffrey J., "Tree Squirrels" (1994). The Handbook: Prevention and Control of Wildlife Damage. 10. https://digitalcommons.unl.edu/icwdmhandbook/10

This Article is brought to you for free and open access by the Wildlife Damage Management, Internet Center for at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in The Handbook: Prevention and Control of Wildlife Damage by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Jeffrey J. Jackson Extension Wildlife Specialist Warnell School of Forest Resources TREE SQUIRRELS University of Georgia Athens, Georgia 30602

Fig. 1. Fox , niger

Damage Prevention and Plastic tubes on wires may prevent Fumigants access to buildings. Control Methods None are registered. Cultural Methods Trapping Exclusion Remove selected trees or their Leghold traps. Install sheet metal bands on isolated branches to prevent access to trees to prevent damage to structures. Box and cage traps. developing nuts. Repellents snap traps. Close external openings to buildings to Naphthalene (moth balls), Ro-pel, Box choker traps. stop damage to building interiors. capsaicin, and polybutenes are Shooting Place an 18-inch (46-cm) section of registered for controlling tree 4-inch (10-cm) diameter plastic pipe squirrels. Effective where firearms are permit- ted. Use a shotgun with No. 6 shot or a one-way door over openings to Toxicants allow squirrels to leave and prevent or a .22-caliber rifle. them from returning. None are registered.

PREVENTION AND CONTROL OF WILDLIFE DAMAGE — 1994 Cooperative Extension Division Institute of Agriculture and Natural Resources University of Nebraska - Lincoln Department of Agriculture and Plant Health Inspection Service Animal Damage Control B-171 Great Plains Agricultural Council Wildlife Committee Identification

In this chapter tree squirrels are divided into three groups: large tree squirrels, squirrels, and flying squirrels. Large tree squirrels include fox (Sciurus niger), eastern gray (Sciurus carolinensis), western gray (Sciurus griseus), and tassel-eared (Sciurus aberti) squirrels. Fox squirrels (Fig. 1) measure 18 to 27 inches (46 to 69 cm) from nose to tip of tail. They weigh about 1 3/4 pounds (787 g) to 2 1/4 pounds (1,012 g). Color Fig. 3. Range of the (dark) varies greatly, from all black in Florida Fig. 2. Range of the (dark) and and (light) in North to silver gray with a white belly in tassel-eared squirrel (light) in North America. America. Maryland. Georgia fox squirrels usu- ally have a black face. Ohio and Michi- gan fox squirrels are grizzled gray-brown above with an orange underside. Sometimes several color variations occur in a single population. Eastern gray squirrels are also variable in color. Some have a distinct reddish cast to their gray coat. Black ones are common in some northern parts of their range. Eastern gray squirrels measure 16 to 20 inches (41 to 51 cm). They weigh from 1 1/4 pounds (567 g) to 1 3/4 pounds (794 g). The western gray squirrel is gray Fig. 4. Range of the (dark) and Fig. 5. Range of the northern above with sharply distinct white (light) in North America. (dark) and (light) in underparts. Size is similar to that of North America. the eastern gray squirrel. Two of flying squirrels occur in where they have been introduced Tassel-eared squirrels are similar in North America. The southern flying (Fig. 2). size to gray squirrels and have several squirrel (Glaucomys volans) is 8 to 10 Eastern gray squirrels have a similar color phases. The most common is inches (20 to 25 cm) long. The northern range to that of fox squirrels but do gray above with a broad reddish band flying squirrel (Glaucomys sabrinus) not occur in many western areas of the down the back. Black tufted ears are averages 2 inches (5 cm) longer. It can fox squirrel’s range. They have been their most distinguishing characteristic be difficult to distinguish between the introduced in several locations in the (the tufts are larger in winter, about 1 two; both may be various shades of West (Fig. 3). inch [2.5 cm]). gray or brown above and lighter There are two species of pine squirrels: below. A sharp line of demarcation Western gray squirrels are confined to the red squirrel (Tamiasciurus separates the darker upper color from west coast states and a small portion of hudsonicus) and Douglas the lighter belly. The most distinctive western Nevada (Fig. 3). characteristics of flying squirrels are (Tamiasciurus douglasii). Pine squirrels Pine squirrels occur across northern the broad webs of skin connecting the are 10 to 15 inches (25 to 38 cm) in total North America south into the Appala- fore and hind legs at the wrists, and length and weigh 1/3 to 2/3 pounds chians and Rockies, and on the west the distinctly flattened tail. (151 to 303 g). Red squirrels are red- coast. brown above with white underparts. Douglas squirrels are gray-brown Range Red squirrels are often associated with above with yellowish underparts. Both coniferous forests. The Douglas squir- species have small ear tufts and often Fox squirrels occur in much of the rel is restricted to the west coast from have a black stripe separating the dark eastern and central United States, as southwestern south upper color from the light belly. well as in several locations in the West, through the Sierras to northern Baja (Fig. 4).

B-172 The tassel-eared squirrel is restricted Pine squirrels are often heavily depen- During fall, squirrels may travel 50 to Ponderosa pine forests in the South- dent on coniferous forests for cones miles (80 km) or more in search of bet- west, usually at altitudes above 5,000 and buds but will also eat a variety of ter . Squirrel populations peri- feet (1,500 m). It occurs in portions of other foods common to gray and fox odically rise and fall. During periods Wyoming, Colorado, New Mexico, squirrel diets. Douglas squirrels of high populations, squirrels—espe- Arizona, and Utah (Fig. 2). depend largely on Ponderosa pine for cially gray squirrels—may go on mass food. Flying squirrels’ food habits are emigrations. At such times many The occurs generally similar to those of other die. across northern North America. Its squirrels. However, they are the most range extends south into the Appala- carnivorous of all tree squirrels. They Fox and gray squirrels are vulnerable chians and Rockies. The southern fly- eat eggs and nestlings, , to numerous parasites and diseases. ing squirrel occurs in the central and and other animal matter when avail- Ticks, mange mites, fleas, and internal eastern United States (Fig. 5). able. Flying squirrels often occupy bird parasites are common. Squirrel hunt- houses, especially bluebird houses. ers often notice bot fly larvae (called Habitat “wolves” or “warbles”) protruding General Biology, from the skin. These fly larvae do not Fox squirrels and gray squirrels impair the quality of the meat for inhabit the same kinds of forests, both Reproduction, and eating. hardwood and coniferous, over much Behavior Squirrels are a food source for , of their range. Gray squirrels are more , , and several mammalian abundant where a high percentage of Fox and gray squirrels breed when predators. Predation seems to have land is forested. In areas with 10% for- they are 1 year old. They breed in mid- little effect on squirrel populations. est cover, fox and gray squirrel popu- December or early January and again lations may be equal. Fox squirrels in June. Young squirrels may breed Typically about half the squirrels in a prefer oak- habitat over much only once in their first year. The gesta- population die each year. In the wild, of their range, especially in the West. tion period is 42 to 45 days. squirrels over 4 years old are rare, In Georgia and Florida, fox squirrels while in captivity individuals may live During the breeding season, noisy seem to prefer pine timber. The west- 10 years or more. mating chases take place when one or ern gray squirrel prefers mixed hard- more males pursue a female through The biology of other North American woods and and dry open the trees. squirrels has much in common with hardwoods. Tassel-eared squirrels are that of fox and gray squirrels, although strongly associated with Ponderosa They in tree cavities, - most other species have one breeding pine. Pine squirrels prefer coniferous made squirrel boxes, or in leaf . season per year. Flying squirrels are forests but also occur in mixed Leaf nests are constructed with a unique in that they are active at night. and hardwood forests, or sometimes frame of sticks filled with dry leaves All other species are active during the in hardwood . and lined with leaves, strips of bark, day. corn husks, or other materials. Sur- Food Habits vival of young in cavities is higher than in leaf nests. Cavities are the pre- Damage Fox and gray squirrels have similar ferred nest sites. Squirrels may occasionally damage food habits. They will eat a great vari- About 3 young comprise a litter. At ety of native foods and adapt quickly forest trees by chewing bark from birth they are hairless, blind, and their branches and trunks. Pine squirrels to unusual food sources. Typically, ears are closed. Newborns weigh they feed on mast (wild tree and damage Ponderosa pine, jack pine, about 1/2 ounce (14 g) at birth and 3 to and paper birch. In the Southeast, fox nuts) in fall and early winter. , 4 ounces (84 to 112 g) at 5 weeks. hickory nuts, walnuts, and osage squirrels damage loblolly and other Young begin to explore outside the . orange fruits are favorite fall foods. nest about the time they are weaned at Nuts are often cached for later use. In 10 to 12 weeks. At weaning they are These species and others may eat late winter and early spring they pre- about half of their adult weight. cones and nip twigs to the extent that fer tree buds. In summer they eat they interfere with natural reseeding of fruits, berries, and succulent plant Home range size depends on the sea- important forest trees. This is a par- materials. Fungi, corn, and cultivated son and availability of food. It may ticular problem in Ponderosa pine fruits are taken when available. During vary from 1 to 100 acres (0.4 to 40 ha). forests where pine squirrels may population peaks, when food is scarce, Squirrels move within their range remove 60% to 80% of the cones in these squirrels may chew bark from a according to availability of food. They poor to fair years. In forest seed variety of trees. They will also eat often seek mast-bearing forests in fall orchards, such squirrel damage insects and other animal matter. and favor tender buds in elm and interferes with commercial seed maple forests in the spring. production.

B-173 In orchards, squirrels can severely Prevent squirrels from traveling on however, because it can cause severe curtail production by eating nuts pre- wires by installing 2-foot (61-cm) sec- distress to people. Supplement this maturely and by carrying off mature tions of lightweight 2- to 3-inch diam- method with lights. A in the attic nuts. In New England orchards, eter (5.1- to 7.6-cm) plastic pipe. Slit may discourage squirrels. pine squirrels may eat ovaries of the pipe lengthwise, spread it open, Ro-pel is a taste repellent that can be cherry blossoms and destroy ripe and place it over the wire. The pipe applied to , bulbs, and flowers; pears. Pine, gray, and fox squirrels will rotate on the wire and cause trav- trees and shrubs; poles and fences; sid- may chew bark of various orchard eling squirrels to tumble. ing and outdoor furniture. Capsaicin is trees. Close openings to attics and other also a taste repellent, registered for use In residential areas, squirrels some- parts of buildings but make sure not to on maple sap collecting equipment. times travel powerlines and short out lock squirrels inside. They may cause a Polybutenes are sticky materials that transformers. They gnaw on wires, great deal of damage in their efforts to can be applied to buildings, railings, enter buildings, and build nests in chew out. Place traps inside as a pre- downspouts, and other areas to keep attics. They frequently chew holes caution after openings are closed. A squirrels from climbing. They can be through pipelines used in maple syrup squirrel excluder can be improvised by messy. A preapplication of masking production. mounting an 18-inch (46-cm) section of tape is recommended. 4-inch (10-cm) plastic pipe over an Squirrels occasionally damage lawns opening. The pipe should point down by burying or searching for and dig- Toxicants at a 45o angle. A one-way door can also ging up nuts. They will chew bark and be used over an opening to let squir- None are registered. clip twigs on ornamental trees or rels out and prevent them from return- shrubbery planted in yards. Often Fumigants ing. squirrels take food at feeders intended None are registered. for . Sometimes they chew to Close openings to buildings with enlarge openings of bird houses and heavy 1/2-inch (1.3-cm) wire mesh or Trapping then enter to eat nestling songbirds. make other suitable repairs. Flying squirrels are small enough to A variety of traps will catch squirrels, Custom-designed wire mesh fences enter most bird houses and are espe- including No. 0 or No. 1 leghold traps, topped with electrified wires may cially likely to eat nesting birds. the “Better Squirrel and Rat Trap,” box effectively keep out squirrels out of traps, and cage traps. Regular rat-sized In gardens, squirrels may eat planted gardens or small orchards. snap traps will catch flying squirrels seeds, mature fruits, or grains such as and small pine squirrels. Glue traps for corn. Habitat Modification will catch small squirrels. Trim limbs and trees to 6 to 8 feet (1.8 Since squirrels are classified as Legal Status to 2.4 m) away from buildings to pre- species in most states, trapping per- vent squirrels from jumping onto mits may be required from your local Fox and gray squirrels are usually clas- roofs. state wildlife agency or municipal Ani- sified as game animals in states where In backyards where squirrels are mal Control office. Wire cage traps they occur. The tassel-eared squirrel is causing problems at bird feeders, and box traps can be used to capture normally a protected species. Check consider providing an alternative squirrels alive. Tie trap doors open for with local or state authorities to deter- food source. Wire or nail an ear of corn 2 to 3 days to get squirrels accustomed mine legal status of squirrels in your to a tree or wooden fence post away to feeding in the traps. Then set the area. from where the squirrels are causing traps and check them twice daily. problems. Inform your neighbors of your trap- ping activities. Translocation of tree Damage Prevention and In high-value crop situations, it may squirrels is a questionable practice Control Methods pay to remove woods or other trees because of the stress placed on trans- near orchards to block the “squirrel ported and resident squirrels and con- Exclusion highway.” cerns regarding the transmission of diseases. Prevent squirrels from climbing iso- Repellents lated trees and power poles by encir- Good baits are slices of orange and Naphthalene (moth balls) may tempo- cling them with a 2-foot-wide (61-cm) apple, walnuts or pecans removed rarily discourage squirrels from enter- collar of metal 6 feet (1.8 m) off the from the shell, and peanut butter. ing attics and other enclosed spaces. ground. Attach metal using encircling Other foods familiar to the squirrel Use of naphthalene in attics of occu- wires held together with springs to may also work well, such as corn or pied buildings is not recommended, allow for tree growth. sunflower seeds.

B-174 Shooting Squirrels caused 177 power outages in Davison, V. E. 1964. Selection of foods by gray Lincoln, Nebraska, in 1980, which was squirrels. J. Wildl. Manage. 28:346-352. Where firearms are permitted, shoot- 24% of all outages. Estimated annual Dolan, P. G., and D. C. Carter. 1977. Glaucomys ing is effective. A shotgun with No. 6 costs were $23,364 for repairs, public volans. . Species 78:1-6. shot or a .22-caliber rifle is suitable. relations, and lost revenue. In Omaha, Check with your state wildlife agency Flyger, V., and J. E. Gates. 1982a. Fox and gray in 1985, squirrels caused 332 outages squirrels. Pages 209-229 in J. A. Chapman for regulations pertaining to the spe- costing at least $47,144. After squirrel and G. A. Feldhamer, eds. Wild of cies in your area. North America: biology, management, and guards were installed over pole- economics. The Johns Hopkins Univ. Press, Other Methods mounted transformers in Lincoln in Baltimore. 1985, annual costs were reduced 78% Flyger, V., and J. E. Gates. 1982b. Pine squirrels. Often several control methods used to $5,148. Pages 230-238 in J. A. Chapman and G. A. simultaneously are more successful Feldhamer, eds. Wild mammals of North than a single method. For example, to America: biology, management, and remove a squirrel from an attic, watch Acknowledgments economics. The Johns Hopkins Univ. Press, Baltimore. squirrels to determine where they enter. Then use repellents and lights to References by Boggess (1980) and Flyger and Hall, R. E., and K. R. Kelson. 1959. The Gates (1982a,b) were particularly useful in drive them out. After squirrels appear mammals of North America, Vol. 1. The preparing this publication. The manuscript Ronald Press Co., New York. 546 pp. to have left the building, use appropri- was read and improved by the comments of ate exclusion methods to keep them Elizabeth McGhee. Hamilton, J. C., R. J. Johnson, R. M. Case, and M. W. Riley. 1988. Assessment of squirrel- out. One or more baited traps will Figure 1 from Schwartz and Schwartz (1981). caused power outages. Vertebr. Pest Control catch squirrels that are accidentally Manage. Mater. 6:34-41. Figures 2 through 4 adapted from Flyger and closed in. This last step is very impor- Gates (1982a,b) by Jill Sack Johnson. Madson, J. 1964. Gray and fox squirrels. Olin tant because locked-in squirrels may Mathieson Chem. Corp. East Alton, Illinois. Figure 5 adapted from Burt and Grossenheider cause damage when they try to chew 112 pp. (1976) by David Thornhill. their way out. Nash, D. J., and R. N. Seaman. 1977. Sciurus aberti. Mammal. Species 80:1-5. Squirrel damage in yards, gardens, For Additional forests, and orchards is often very dif- National Pest Control Association. 1964. Tree ficult to control. During population Information squirrels—a fact sheet. Nat. Pest Control Assoc. Tech. Release 20-64. highs, new squirrels arrive quickly to replace those shot or trapped. Baumgartner, L. L. 1940. Trapping, handling Schwartz, C. W., and E. R. Schwartz. 1981. The and marking fox squirrels. J. Wildl. Manage. wild mammals of Missouri, rev. ed. Univ. 4:444-450. Missouri Press, Columbia. 356 pp. Economics of Damage Boggess, E. K. 1980. Tree squirrels. in F. R. Henderson, ed. Prevention and control of and Control wildlife damage. Great Plains Agric. Council and Kansas Coop. Ext. Serv. Kansas State Squirrels cause economic losses to Univ., Manhattan. Editors homeowners, nut growers, and forest Burt, W. H., and R. P. Grossenheider. 1976. A Scott E. Hygnstrom managers. The extent of these losses is field guide to the mammals, 3d ed. Robert M. Timm not well known. Houghton Mifflin Co. Boston. 289 pp. Gary E. Larson

B-175 B-176