TREE SQUIRRELS - ICWDM Home Page

1 B-171 TREE SQUIRRELSJ effrey J. JacksonExtension Wildlife SpecialistWarnell School of Forest ResourcesUniversity of GeorgiaAthens, Georgia 30602 Fig. 1. Fox squirrel , Sciurus nigerDamage Prevention andControl MethodsExclusionInstall sheet metal bands on isolatedtrees to prevent damage todeveloping external openings to buildings tostop damage to building an 18-inch (46-cm) section of4-inch (10-cm) diameter plastic pipeor a one-way door over openings toallow SQUIRRELS to leave and preventthem from tubes on wires may preventaccess to MethodsRemove selected trees or theirbranches to prevent access (moth balls), Ro-pel,capsaicin, and polybutenes areregistered for controlling are are and cage snap choker where firearms are permit-ted. Use a shotgun with No. 6 shotor a .22-caliber AND CONTROL OF WILDLIFE DAMAGE 1994 Cooperative Extension DivisionInstitute of Agriculture and Natural ResourcesUniversity of Nebraska - LincolnUnited States Department of AgricultureAnimal and Plant Health Inspection ServiceAnimal Damage ControlGreat Plains Agricultural CouncilWildlife CommitteeB-172 IdentificationIn this chapter tree SQUIRRELS aredivided into three groups: large treesquirrels, pine SQUIRRELS , and flyingsquirrels.

2 Large tree SQUIRRELS includefox (Sciurus niger), eastern gray (Sciuruscarolinensis), western gray (Sciurusgriseus), and tassel-eared (Sciurusaberti) SQUIRRELS (Fig. 1) measure 18 to 27inches (46 to 69 cm) from nose to tip oftail. They weigh about 1 3/4 pounds(787 g) to 2 1/4 pounds (1,012 g). Colorvaries greatly, from all black in Floridato silver gray with a white belly inMaryland. Georgia fox SQUIRRELS usu-ally have a black face. Ohio and Michi-gan fox SQUIRRELS are grizzledgray-brown above with an orangeunderside. Sometimes several colorvariations occur in a single gray SQUIRRELS are also variablein color. Some have a distinct reddishcast to their gray coat. Black ones arecommon in some northern parts oftheir range. Eastern gray squirrelsmeasure 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 grayabove with sharply distinct whiteunderparts.

3 Size is similar to that ofthe eastern gray SQUIRRELS are similar insize to gray SQUIRRELS and have severalcolor phases. The most common isgray above with a broad reddish banddown the back. Black tufted ears aretheir most distinguishing characteristic(the tufts are larger in winter, about 1inch [ cm]).There are two species of pine SQUIRRELS :the red squirrel (Tamiasciurushudsonicus) and Douglas pine squirrel (Tamiasciurus douglasii). Pine squirrelsare 10 to 15 inches (25 to 38 cm) in totallength and weigh 1/3 to 2/3 pounds(151 to 303 g). Red SQUIRRELS are red-brown above with white SQUIRRELS are gray-brownabove with yellowish underparts. Bothspecies have small ear tufts and oftenhave a black stripe separating the darkupper color from the light they have been introduced(Fig. 2).Eastern gray SQUIRRELS have a similarrange to that of fox SQUIRRELS but donot occur in many western areas of thefox squirrel s range.

4 They have beenintroduced in several locations in theWest (Fig. 3).Western gray SQUIRRELS are confined towest coast states and a small portion ofwestern Nevada (Fig. 3).Pine SQUIRRELS occur across northernNorth America south into the Appala-chians and Rockies, and on the SQUIRRELS are often associated withconiferous forests. The Douglas squir-rel is restricted to the west coast fromsouthwestern British Columbia souththrough the Sierras to northern BajaCalifornia (Fig. 4).Fig. 2. Range of the fox squirrel (dark) andtassel-eared squirrel (light) in North 3. Range of the eastern gray squirrel (dark)and western gray squirrel (light) in 4. Range of the red squirrel (dark) andDouglas squirrel (light) in North 5. Range of the northern flying squirrel (dark) and southern flying squirrel (light) inNorth species of flying SQUIRRELS occur inNorth America.

5 The southern flyingsquirrel (Glaucomys volans) is 8 to 10inches (20 to 25 cm) long. The northernflying squirrel (Glaucomys sabrinus)averages 2 inches (5 cm) longer. It canbe difficult to distinguish between thetwo; both may be various shades ofgray or brown above and lighterbelow. A sharp line of demarcationseparates the darker upper color fromthe lighter belly. The most distinctivecharacteristics of flying SQUIRRELS arethe broad webs of skin connecting thefore and hind legs at the wrists, andthe distinctly flattened SQUIRRELS occur in much of theeastern and central United States, aswell as in several locations in the West,B-173 The tassel-eared squirrel is restrictedto Ponderosa pine forests in the South-west, usually at altitudes above 5,000feet (1,500 m). It occurs in portions ofWyoming, Colorado, New Mexico,Arizona, and Utah (Fig. 2).The northern flying squirrel occursacross northern North America.

6 Itsrange extends south into the Appala-chians and Rockies. The southern fly-ing squirrel occurs in the central andeastern United States (Fig. 5).HabitatFox SQUIRRELS and gray squirrelsinhabit the same kinds of forests, bothhardwood and coniferous, over muchof their range. Gray SQUIRRELS are moreabundant where a high percentage ofland is forested. In areas with 10% for-est cover, fox and gray squirrel popu-lations may be equal. Fox squirrelsprefer oak-hickory habitat over muchof their range, especially in the Georgia and Florida, fox squirrelsseem to prefer pine timber. The west-ern gray squirrel prefers mixed hard-woods and conifers and dry openhardwoods. Tassel-eared SQUIRRELS arestrongly associated with Ponderosapine. Pine SQUIRRELS prefer coniferousforests but also occur in mixed coniferand hardwood forests, or sometimesin hardwood HabitsFox and gray SQUIRRELS have similarfood habits.

7 They will eat a great vari-ety of native foods and adapt quicklyto unusual food sources. Typically,they feed on mast (wild tree fruits andnuts) in fall and early winter. Acorns,hickory nuts, walnuts, and osageorange fruits are favorite fall are often cached for later use. Inlate winter and early spring they pre-fer tree buds. In summer they eatfruits, berries, and succulent plantmaterials. Fungi, corn, and cultivatedfruits are taken when available. Duringpopulation peaks, when food is scarce,these SQUIRRELS may chew bark from avariety of trees. They will also eatinsects and other animal SQUIRRELS are often heavily depen-dent on coniferous forests for conesand buds but will also eat a variety ofother foods common to gray and foxsquirrel diets. Douglas squirrelsdepend largely on Ponderosa pine forfood. Flying SQUIRRELS food habits aregenerally similar to those of othersquirrels.

8 However, they are the mostcarnivorous of all tree SQUIRRELS . Theyeat bird eggs and nestlings, insects,and other animal matter when avail-able. Flying SQUIRRELS often occupy birdhouses, especially bluebird Biology,Reproduction, andBehaviorFox and gray SQUIRRELS breed whenthey are 1 year old. They breed in mid-December or early January and againin June. Young SQUIRRELS may breedonly once in their first year. The gesta-tion period is 42 to 45 the breeding season, noisymating chases take place when one ormore males pursue a female throughthe nest in tree cavities, human-made squirrel boxes, or in leaf nests are constructed with aframe of sticks filled with dry leavesand lined with leaves, strips of bark,corn husks, or other materials. Sur-vival of young in cavities is higherthan in leaf nests. Cavities are the pre-ferred nest 3 young comprise a litter.

9 Atbirth they are hairless, blind, and theirears are closed. Newborns weighabout 1/2 ounce (14 g) at birth and 3 to4 ounces (84 to 112 g) at 5 begin to explore outside thenest about the time they are weaned at10 to 12 weeks. At weaning they areabout half of their adult range size depends on the sea-son and availability of food. It mayvary from 1 to 100 acres ( to 40 ha). SQUIRRELS move within their rangeaccording to availability of food. Theyoften seek mast-bearing forests in falland favor tender buds in elm andmaple forests in the fall, SQUIRRELS may travel 50miles (80 km) or more in search of bet-ter habitat. squirrel populations peri-odically rise and fall. During periodsof high populations, SQUIRRELS espe-cially gray SQUIRRELS may go on massemigrations. At such times manyanimals and gray SQUIRRELS are vulnerableto numerous parasites and , mange mites, fleas, and internalparasites are common.

10 squirrel hunt-ers often notice bot fly larvae (called wolves or warbles ) protrudingfrom the skin. These fly larvae do notimpair the quality of the meat are a food source for hawks,owls, snakes, and several mammalianpredators. Predation seems to havelittle effect on squirrel about half the SQUIRRELS in apopulation die each year. In the wild, SQUIRRELS over 4 years old are rare,while in captivity individuals may live10 years or biology of other North Americansquirrels has much in common withthat of fox and gray SQUIRRELS , althoughmost other species have one breedingseason per year. Flying SQUIRRELS areunique in that they are active at other species are active during may occasionally damageforest trees by chewing bark frombranches and trunks. Pine squirrelsdamage Ponderosa pine, jack pine,and paper birch. In the Southeast, foxsquirrels damage loblolly and species and others may eatcones and nip twigs to the extent thatthey interfere with natural reseeding ofimportant forest trees.