Animal Diversity Web

Ge­o­graphic Range

Red-tailed squir­rels are found in Cen­tral and South Amer­ica. Their range in­cludes north­ern Costa Rica, south­ern Venezuela, Co­lum­bia, Panama, and Ecuador. Sci­u­rus granaten­sis are also found on the is­lands of Mar­garita, To­bago, Trinidad, and Barro Col­orado Is­land. Red-tailed squir­rels are found from sea level to 3,000 me­ters, al­though in Venezuela 93% of red-tailed squir­rels are found below 1,500 m. (Emamdie and War­ren, 1993; Heaney and Thor­ing­ton, Jr., 1978; Ni­tik­man, 1985; Nowak, 1999; Thor­ing­ton, Jr. and Hoff­mann, 2005)

• Biogeographic Regions
• neotropical
  • native

Habi­tat

Red-tailed squir­rels are found in a va­ri­ety of habi­tats. They are found in both trop­i­cal and sea­sonal forests, in close prox­im­ity to water, and in crop­lands close to human pop­u­la­tions. They are pri­mar­ily found in sea­sonal rain­forests in­hab­it­ing lower for­est lay­ers. (Heaney and Thor­ing­ton, Jr., 1978; Ni­tik­man, 1985)

• Habitat Regions
• tropical
• terrestrial

• Terrestrial Biomes
• forest
• rainforest

• Range elevation

  0 to 3,000 m

  0.00 to ft

Phys­i­cal De­scrip­tion

Red-tailed squir­rels are medium-sized squir­rels. Their color varies greatly across the range of the species, es­pe­cially in dif­fer­ent habi­tats. Their dor­sal sur­face is often dark or­ange, but can range from dull yel­low sprin­kled with black to all black. Some va­ri­eties of red-tailed squir­rels have a me­dian, dor­sal stripe. Their ven­tral color ranges from com­pletely white to bright or­ange-rust. The well-furred tail is dull yel­low­ish brown and may or may not in­clude a black tip. The ven­tral tail varies from dark yel­low­ish brown to black with a dark yel­low edge. The chin and sides of the throat are dark col­ored with dark yel­low high­lights with a yel­low­ish-brown ring sur­round­ing the eyes. The win­ter coat color may vary slightly from the sum­mer coat. Red-tailed squir­rels vary in size through­out their ge­o­graphic range. Males and fe­males tend to be around the same size, al­though fe­males tend to be slightly larger on Barro Col­orado Is­land in Panama. Body masses range from 228 to 520 g with body length rang­ing from 330 to 520 mm. Tail length is 140 to 280 mm. The length of the hind feet is 40 to 65 mm, the length of each ear is 16 to 36 mm, the length of the skull is 42.5 to 68.3 mm, and the width of the cra­nium is 20.0 to 25.6 mm. Sci­u­rus granaten­sis has a broad skull that is deep in the or­bital re­gion. The cra­nium is arched, the snout is long, and the bul­lae are small. (Heaney and Thor­ing­ton, Jr., 1978; Ni­tik­man, 1985; Nowak, 1999)

• Other Physical Features
• endothermic
• homoiothermic
• bilateral symmetry

• Sexual Dimorphism
• sexes alike
• female larger

• Range mass

  228 to 520 g

  8.04 to 18.33 oz

• Range length

  330 to 520 mm

  12.99 to 20.47 in

Re­pro­duc­tion

Red-tailed squir­rels gen­er­ally breed from late De­cem­ber or early Jan­u­ary through Oc­to­ber. Some red-tailed squir­rels may grunt, squeal, and chase each other, but it is not known if that is a mat­ing be­hav­ior. Dur­ing mat­ing sea­son, males begin to search for and fol­low fe­males three or more days be­fore they come into heat. The day the fe­male comes into heat, many males begin to enter her home range and chase her until mat­ing oc­curs. The male loses in­ter­est within 15 to 30 min­utes fol­low­ing mat­ing. (Flem­ing, 1970; Ni­tik­man, 1985)

• Mating System
• polyandrous

The ges­ta­tion pe­riod of red-tailed squir­rels is less than two months. Young are born hair­less and with closed eyes weigh­ing ap­prox­i­mately 9 to 10 g at birth. The lit­ter size is usu­ally 1 or 2 squir­rels, al­though in rare cases lit­ter size may be up to 3. Red-tailed squir­rels can have 2 to 3 lit­ters per year. Fur be­gins to grow on the young ap­prox­i­mately 14 days after birth and their eyes open ap­prox­i­mately 30 to 32 days after birth. (Heaney and Thor­ing­ton, Jr., 1978; Ko­prowskia and Lurzb, 2007; Ni­tik­man, 1985; Nowak, 1999; de Ma­g­a­l­haes and Costa, 2009)

• Key Reproductive Features
• iteroparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• viviparous

• Breeding interval

  Red-tailed squirrels have 2 to 3 litters per year.

• Breeding season

  Red-tailed squirrels breed from late December to late October.

• Range number of offspring

  1 to 3

• Average number of offspring

  1.93

• Range gestation period

  2 (high) months

• Average weaning age

  61 days

• Average age at sexual or reproductive maturity (female)

  1 years

• Average age at sexual or reproductive maturity (male)

  1 years

Young stay in the nest ap­prox­i­mately six weeks after birth. When the mother leaves the nest, she cov­ers her young with nest ma­te­r­ial. After the pe­riod of lac­ta­tion, which is ap­prox­i­mately 61 days, the mother leaves her young. Males have no parental in­volve­ment in their young. (Heaney and Thor­ing­ton, Jr., 1978)

• Parental Investment
• altricial
• female parental care
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female

Lifes­pan/Longevity

Not much is known about the lifes­pan of red-tailed squir­rels in the wild, but it is es­ti­mated that max­i­mum lifes­pan is be­tween 6 and 7 years. Dur­ing a study on Barro Col­orado Is­land, an in­di­vid­ual that was ap­prox­i­mately 1 year old, was cap­tured and marked and re-cap­tured mul­ti­ple times for 6 years. The max­i­mum lifes­pan in cap­tiv­ity is ap­prox­i­mately 11.5 years. (Heaney and Thor­ing­ton, Jr., 1978; Ni­tik­man, 1985; de Ma­g­a­l­haes and Costa, 2009)

• Average lifespan
  Status: wild

  7 years

• Average lifespan
  Status: captivity

  11.5 years

Be­hav­ior

Red-tailed squir­rels are usu­ally soli­tary and are only seen in groups when breed­ing, feed­ing, or with their young. Even when they are in groups, red-tailed squir­rels usu­ally avoid each other. Adult fe­male red-tailed squir­rels are usu­ally not seen within 10 m of other in­di­vid­u­als, but they have been doc­u­mented chas­ing each other. They avoid one an­other while feed­ing and are never found in the same tree at one time. The ma­jor­ity of their day (64%) is spent sit­ting, while only about 3% is spent grasp­ing, jump­ing, climb­ing, or doing other ac­tiv­i­ties. Red-tailed squir­rels are gen­er­ally silent, un­less they are alarmed, dur­ing which they will let out a few short, hoarse sounds. They also have been known to let out grunts and squeals. Red-tailed squir­rels travel 50% of the time on the trunks and large branches close to the cen­ter of trees. (Flem­ing, 1970; Gar­ber and Suss­man, 1984; Ni­tik­man, 1985)

• Key Behaviors
• arboreal
• scansorial
• diurnal
• motile
• sedentary
• solitary

Home Range

The av­er­age home range area of males is es­ti­mated to be 1.5 ha. and the av­er­age home range of fe­males is es­ti­mated to be 0.65 ha. On a study done in Panama, home range for males was 0.83 ha to 2.15 ha. Fe­males home ranges were 0.39 ha to 0.86 ha. Male home ranges over­lap greatly with one an­other and over­lap with home ranges of fe­males. Fe­male home ranges do not usu­ally over­lap. (Heaney and Thor­ing­ton, Jr., 1978; Ni­tik­man, 1985; Nowak, 1999)

Com­mu­ni­ca­tion and Per­cep­tion

Nor­mally Sci­u­rus granaten­sis are quiet and soli­tary, but they often let out grunts and squeals and chase each other. This may or may not a mat­ing be­hav­ior. Like other squir­rels, they use body pos­tures and ges­tures to com­mu­ni­cate and have a keen sense of smell used to find food and de­ter­mine sex­ual re­cep­tiv­ity. (Flem­ing, 1970)

• Communication Channels
• visual
• acoustic
• chemical

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

Ap­prox­i­mately 65% of the diet of red-tailed squir­rels is made up of fruits, nuts, and seeds with the ma­jor­ity of their diet com­ing from Schee­lea zo­nen­sis, Dipteryx pana­men­sis, Maripa pana­men­sis, and Gus­tavia su­perba. Al­though they feed mainly on large fruits and seeds, their diet may in­clude leaves, bark, mush­rooms, and flow­ers. A study done on Barro Col­orado Is­land found that 73% of total feed­ing ob­ser­va­tions were on four species of fruit; Dipteryx pana­men­sis, As­tro­caryum stan­d­leyum, Schee­lea zo­nen­sis, and Gus­tavia su­perba. When avail­able, acorns and hick­ory nuts are greatly pre­ferred. Red-tailed squir­rels have been doc­u­mented feed­ing on small in­sects. In areas where hu­mans re­side, red-tailed squir­rels feed on cul­ti­vars, man­gos, av­o­ca­dos, maize, co­conuts, and ba­nanas caus­ing dam­age to these crops. In cen­tral Panama, red-tailed squir­rels pre­fer feed­ing on hard-shelled nuts over softer-shelled nuts. Red-tailed squir­rels mainly search for food on the ground, but will usu­ally climb up into the trees be­fore eat­ing food they have found. They also look for food in the crowns of trees over 30 m above the ground. (Gar­ber and Suss­man, 1984; Glanz, 1984; Heaney and Thor­ing­ton, Jr., 1978; Ni­tik­man, 1985; Nowak, 1999)

• Primary Diet
• herbivore
  • frugivore
  • granivore

• Animal Foods
• insects

• Plant Foods
• leaves
• wood, bark, or stems
• seeds, grains, and nuts
• fruit
• flowers

• Other Foods
• fungus

Pre­da­tion

Hu­mans oc­ca­sion­ally prey on red-tailed squir­rels, both for food and to re­duce their im­pact on crops, such as man­gos, av­o­ca­dos, corn, co­conuts, and ba­nanas. Nat­ural preda­tors in­clude ca­puchin mon­keys (Cebus ca­puci­nus) and boa con­stric­tors (Boa con­stric­tor). They may also be preyed on by rap­tors, fe­lids, and ar­bo­real snakes. (Ni­tik­man, 1985; Wright, et al., 2000)

• Known Predators

  • humans (Homo sapiens)
  • capuchin monkeys (Cebus capucinus)
  • boa constrictors (Boa constrictor)

Ecosys­tem Roles

Red-tailed squir­rels dis­perse the seeds of the fruits that they feed on and serve as prey for preda­tors. They may con­tribute to the dis­per­sal of fun­gal spores as well. (Steven and Putz, 1984)

• Ecosystem Impact
• disperses seeds

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Red-tailed squir­rels dis­perse seeds of the plants they feed on. Sci­u­rus granaten­sis are hunted for food by hu­mans. (Ni­tik­man, 1985; Wright, et al., 2000)

• Positive Impacts
• food

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

In areas of human pop­u­la­tion, red-tailed squir­rels feed on crops such as man­gos, av­o­ca­dos, maize, co­conuts, and ba­nanas, caus­ing crop dam­age. (Ni­tik­man, 1985)

• Negative Impacts
• crop pest

Con­ser­va­tion Sta­tus

Red-tailed squir­rels have a sta­ble pop­u­la­tion stand­ing. They are nei­ther en­dan­gered nor close to ex­tinc­tion even though they are hunted by hu­mans.

• IUCN Red List

  Least Concern

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  No special status

Other Com­ments

Sci­u­rus granaten­sis, along with many other species of Sci­u­rus swim by dog pad­dling. (Nowak, 1999)

Con­trib­u­tors

Casey Har­rell (au­thor), Rad­ford Uni­ver­sity, Joel Hagen (ed­i­tor), Rad­ford Uni­ver­sity, Tanya Dewey (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

Emamdie, D., J. War­ren. 1993. Va­ri­etal Taste Pref­er­ence for Cacao Theo­broma cacao L. by the Neotrop­i­cal Red Squir­rel Sci­u­rus granaten­sis (Hum­boldt). Biotrop­ica, 25: 365.

Flem­ing, T. 1970. Notes on the Ro­dent Fau­nas of Two Pana­man­ian Forests. Jour­nal of Mam­mal­ogy, 51(3): 475.

Gar­ber, P., R. Suss­man. 1984. Eco­log­i­cal Dis­tinc­tions Be­tween Sym­patric Species of Sagui­nus and Sci­u­rus. Amer­i­can Jour­nal of Phys­i­cal An­thro­pol­ogy, 65: 135-146.

Glanz, W. 1984. Food and Habi­tat use by two Sym­patric Sci­u­rus Species in Cen­tral Panama. Jour­nal of Mam­mal­ogy, 65(2): 342-347.

Heaney, L., R. Thor­ing­ton, Jr.. 1978. Ecol­ogy of Neotrop­i­cal Red-Tailed Squir­rels, Sci­u­rus granaten­sis, in the Panama Canal Zone. Jour­nal of Mam­mal­ogy, 59(4): 846-851.

Ko­prowskia, J., P. Lurzb. 2007. Tree Squir­rel In­tro­duc­tion: A The­o­ret­i­cal Ap­proach with Pop­u­la­tion Vi­a­bil­ity Analy­sis. Jour­nal of Mam­mal­ogy, 88(5): 1271-1279.

Ni­tik­man, L. 1985. Sci­u­rus granaten­sis. Mam­malian Species, 246: 1-8.

Nowak, R. 1999. Order Ro­den­tia. Pp. 1265-1268 in Walker's Mam­mals of the World, Vol. 2, Sixth Edi­tion. Bal­ti­more and Lon­don: The Johns Hop­kins Uni­ver­sity Press.

Steven, D., F. Putz. 1984. Im­pact of Mam­mals on Early Re­cruit­ment of a Trop­i­cal Canopy Tree, Dipteryx pana­men­sis, in Panama. Oikos, 43(2): 207-216.

Thor­ing­ton, Jr., R., R. Hoff­mann. 2005. Fam­ily Sci­uri­dae. Pp. 761 in D Wil­son, D Reeder, eds. Mam­mal Species of the World, Vol. 2, Third Edi­tion. Bal­ti­more, Mary­land: The Johns Hop­kins Uni­ver­sity Press.

Wright, S., R. Ibáñez, M. Moreno, M. Gal­lardo, I. Dominguex, H. Ze­bal­los. 2000. Poach­ers Alter Mam­mal Abun­dance, Seed Dis­per­sal, and Seed Pre­da­tion in a Neotrop­i­cal For­est. Con­ser­va­tion Bi­ol­ogy, 14(1): 227-239.

de Ma­g­a­l­haes, J., J. Costa. 2009. A data­base of ver­te­brate longevity records and their re­la­tion to other life-his­tory traits. Jour­nal of Evo­lu­tion­ary Bi­ol­ogy, 22(8): 1770-1774.