Sciurus variegatoidesvariegated squirrel

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Geographic Range

Variegated squirrels (Sciurus variegatoides) are found in North and Central America, from southern Chiapas, Mexico to Central Panama. (Best, 1995; Eisenberg, 1989; Emmons, 1990; Reid, 1997)

Habitat

Sciurus variegatoides occupies both dry and wet tropical forests, but prefers open, arid environments. It is found in deciduous, semi-deciduous, and, at times, evergreen forest. It is frequently found in open woodland, scrubland, and plantations. It lives at elevations ranging from sea level to 2500 m. (Best, 1995; Emmons, 1990; Reid, 1997)

  • Range elevation
    0 to 2500 m
    0.00 to 8202.10 ft

Physical Description

Sciurus variegatoides is a large, long-tailed species of tree squirrel. Its pelage is shiny and bristly. The fourteen different subspecies exhibit a wide range of color and color pattern. Dorsally, the color ranges from blackish to reddish brown to yellowish-gray to white. On the underside, the color ranges from white to cinnamon-buff. The feet and sides of the body are pale gray or yellowish; the ears have a pale patch of fur on the outside. Different subspecies may have a combination of dorsal and lateral stripes and forehead patches or may be completely grizzled in coloration. The guard hairs on the back and sides are agouti, and are made up of several different color bands. The underside is not usually banded. The tail is bushy and long and has black hairs tipped in white on its dorsal side. The underside of the tail is usually lighter in color. (Best, 1995; Emmons, 1990; Harris, 1937)

There is little seasonal change in the coat of S. variegatoides. It has no melanistic phase. Molts begin in April or May, and the new pelage is in by September and October. There is considerable variation in time of molt, with individuals in molt occurring every month of the year. An individual may only molt once a year. The darkest subspecies are found in the areas with the greatest rainfall, along the Caribbean coast (S. v. belti, S. v. managuensis, S. v. artrirufus, and S. v. thomasi). Lighter subspecies are found along the Pacific side of Central America (S .v. bangsi, S. v. dorsalis, S. v. goldmani, and S. v. helveolus). (Best, 1995; Harris, 1937)

The dental formula for variegated squirrels is I 1/1, C 0/0, P 2/1, M 3/3, total 22. There is no size difference between males and females, although there is considerable variation among individuals of the same subspecies in the same location. Head and body length varies from 220 to 337 mm. Tail length varies from 226 to 325 mm. Length of the hind foot is from 45 to 70 mm. Length of the ear is 20 to 35 mm. Variegated squirrels weigh from 428 to 909 g. Measurements of bacula are as follows: length is 12.1 mm, length of tip is 2.6 mm, height of tip is 3.0 mm, height of base is 3.0 mm, and width of base is 2.4 mm. Measurements of baubella are as follows: length is 3.9 mm and width of disc is 2.0 mm. Females have eight mammae; one pair pectoral, two pair abdominal, and one pair inguinal. (Best, 1995; Emmons, 1990)

Variegated squirrels are similar to many other tree squirrel species. There are some distinguishing characteristics however. The red-tailed squirrels have an orange tail, are smaller, and occur in denser, wetter forests; Deppe's squirrels have a slender tail, gray underside and feet, and are smaller; Yucatan squirrels are gray and smaller; Mexican gray squirrels lack the prominent pale ear patches. (Best, 1995; Emmons, 1990; Reid, 1997)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    428 to 909 g
    15.08 to 32.04 oz
  • Range length
    220 to 337 mm
    8.66 to 13.27 in

Reproduction

Little is known about the mating system of S. variegatoides, but most tree squirrels (Sciurus) are similar in their mating and reproduction. Tree squirrels are generally solitary, with individuals coming into contact only to mate. Social ranking of tree squirrels is based on weight and age. The higher ranking males will have more mates. A female tree squirrel goes into estrus once a year for the duration of one day. Through olfactory cues and behavioral changes, males know when to mate with her. More than one male may enter the territory of a female in estrus, and males may fight one another in order to mate. After mating, the male and female separate. There are no lasting pair bonds. (Gurnell, 1987; Walker, 1983)

In Panama, breeding occurs annually for S. variegatoides between April and May. Female variegated squirrels build nests high up in the trees and have their babies there. Nest materials include twigs and leaves, and nests are usually waterproof. The average number of young per litter ranges from 2 to 8. Young born to the subspecies S. v. melania have the characteristic dark color of the adult. (Best, 1995; Klein, 1977)

In Sciurus, gestation lasts between 33-46 days. When tree squirrels are born, they are blind and naked. Their digits are fused together, and they weigh less than one ounce. After 4 days, babies are vocal, emitting squeaks in response to their mother’s stimuli. After 2 weeks, they begin to develop fur. Between 30 to 32 days babies develop teeth and open their eyes. By 4 weeks, the young are learning to groom themselves, and they leave the nest by 6 weeks. Squirrels begin to socialize at 10 weeks just after they are weaned. They are solitary by 15 weeks. Tree squirrels reach sexual maturity between 12 to 15 weeks. (Gurnell, 1987; Walker, 1983)

  • Breeding interval
    Sciurus variegatoides mates once a year.
  • Breeding season
    Breeding occurs for S. variegatoides between April and May.
  • Range number of offspring
    2 to 8
  • Average number of offspring
    6-8
  • Range gestation period
    33 to 46 days
  • Average weaning age
    10 weeks
  • Average time to independence
    15 weeks
  • Range age at sexual or reproductive maturity (female)
    12 to 15 weeks
  • Range age at sexual or reproductive maturity (male)
    12 to 15 weeks

Little is known about parental investment in the species S. variegatoides. In most members of the genus Sciurus, the father offers no parental care. The mother builds a nest for her young and they reside there until 6 weeks. The mother will cover her nest with brush, in order to protect her young, while she is scavenging for food. Young tree squirrels are weaned at 10 weeks and are independent of their mother after 15 weeks. The mother is responsible for showing the young how to scavenge for food and groom. (Best, 1995; Gurnell, 1987; Walker, 1983)

  • Parental Investment
  • altricial
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • protecting
      • female
  • extended period of juvenile learning

Lifespan/Longevity

For the genus, the longest living Sciurus was 23 years in captivity and 8 to 12 years in the wild. (Gurnell, 1987; Walker, 1983)

  • Range lifespan
    Status: wild
    12 (high) years
  • Range lifespan
    Status: captivity
    23 (high) years
  • Average lifespan
    Status: captivity
    15.1 years
    AnAge

Behavior

Variegated squirrels are solitary, arboreal mammals. They build nests in tall, slender trees usually at the junction between a limb and the main trunk of the tree. There is approximately one nest per 2.4 ha. The squirrels are diurnal, being most active during the early morning. They spend almost all of their time in the trees and are very agile, running and leaping from one branch to the next with ease. They cross open areas via fence rows and lower trees. (Best, 1995; Emmons, 1990; Klein, 1977; Reid, 1997)

Members of the genus Sciurus do not hibernate, but they may remain inactive during periods of cold or inclement weather until they need food. In general, interspecific competition is averted by maintaining strict niches where species overlap. (Gurnell, 1987; Walker, 1983)

Home Range

In general, males of the genus Sciurus have larger home ranges than females, and they may overlap with those of other males and females. The home ranges of females do not overlap and are generally smaller. (Gurnell, 1987; Walker, 1983)

Communication and Perception

Variegated squirrels make chucking sounds when alarmed. Harsh chatter is also occasionally heard. Female tree squirrels use chemical cues to show males when they are ready to mate. (Emmons, 1990; Gurnell, 1987; Reid, 1997)

Food Habits

Sciurus variegatoides consumes nuts and fruits of various kinds, including hard-shelled and soft, thin-shelled seeds of fruits such as Scheelea rostrata, Scheelea zonensis, Crescentia alata, Guazuma ulmifolia, Quercus oleoides, Sterculia apetala, Mangiferea indica, Spondias mombin, Bursera simaruba, Ochroma pyramidale, Cochlospermum vitifolium, Enterolobium cyclocarpum, Cecropia, Ficus insipida, Astrcarum standleyanum, Scheelea zonensis, Genipa americana, Apeiba tibourbou, Luehea speciosa, and Trema micrantha. It spends most of its time foraging for soft, juicy fruits. It also eat some vines, flowers, and fungi. (Best, 1995; Emmons, 1990)

  • Plant Foods
  • seeds, grains, and nuts
  • fruit
  • flowers
  • Other Foods
  • fungus

Predation

The predators of S. variegatoides are generally opportunistic. The following information is in regards to the genus Sciurus: Predators of adult tree squirrels include weasels (Mustela), martens (Martes), wildcats (Felidae), foxes (Canidae), eagles (Accipitridae), owls (Strigiformes), and snakes (Serpentes). These predators may also feed on young, taking them directly from the nest. (Gurnell, 1987)

Ecosystem Roles

Sciurus variegatoides serves an important role in seed dispersal via the fruit it consumes. Ectoparasites of variegated squirrels include chiggers and lice. No endoparasites are known. (Best, 1995)

Ectoparasites of tree squirrels (genus Sciurus) include Acari, Anoplura, Siphonaptera, and Diptera. Endoparasites include Protozoa, Cestodes, and Nematodes. (Gurnell, 1987)

  • Ecosystem Impact
  • disperses seeds
Commensal/Parasitic Species

Economic Importance for Humans: Positive

Variegated squirrels are hunted by humans for sport and for meat. (Best, 1995; Emmons, 1990)

  • Positive Impacts
  • food

Economic Importance for Humans: Negative

Variegated squirrels are considered crop pests in some areas. (Best, 1995; Walker, 1983)

  • Negative Impacts
  • crop pest

Conservation Status

There is no special conservation status for variegated squirrels. This species may be considered "fragile" in some parts of its range in Mexico. (Best, 1995)

Other Comments

Some commonly used names for S. variegatoides include ardilla jaspeada, chiza, and ardilla negra. Sciurus comes from the Latin word meaning squirrel and variegatoides signifies the variable coloration of the species. (Best, 1995)

Contributors

Matthew Wund (editor), University of Michigan-Ann Arbor.

Kelly Carr (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

food

A substance that provides both nutrients and energy to a living thing.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

frugivore

an animal that mainly eats fruit

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

saltatorial

specialized for leaping or bounding locomotion; jumps or hops.

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Best, T. 1995. Mammalian Species: Sciurus variegatoides. The American Society of Mammalogists, 500: 1-6. Accessed March 20, 2004 at http://www.science.smith.edu/departments/Biology/VHAYSSEN/msi/.

Eisenberg, J. 1989. Mammals of the Neotropics. Chicago: University of Chicago Press.

Emmons, L. 1990. Neotropical Rainforest Mammals: A Field Guide. Chicago: University of Chicago Press.

Gurnell, J. 1987. The natural history of squirrels. New York: Facts on File.

Harris, W. 1937. Revision of Sciurus variegatoides, a species of Central American squirrel. Miscellaneous publications, University of Michigan, Musuem of Zoology, 38: 5-39.

Klein, E. 1977. Mamiferos de Honduras. Tegucigalpa, D.C.: Secretaria de Recursos Naturales.

Reid, F. 1997. A field guide to the mammals of Central America and Southeast Mexico. New York: Oxford University Press.

Walker, E. 1983. Walker's Mammals of the World. Baltimore: Johns Hopkins University Press.