The Arizona gray squirrel (''Sciurus arizonensis'') is a

tree squirrel Tree squirrels are the members of the squirrel Family (biology), family (Sciuridae) commonly just referred to as "squirrels." They include more than 100 arboreal species native to all continents except Antarctica and Oceania. They do not form a ...

, in the genus ''

Sciurus The genus ''Sciurus'' contains most of the common, bushy-tailed squirrels in North America, Europe, temperate Asia, Central America and South America. Species The number of species in the genus is subject to change. In 2005, Thorington & Hoff ...

'',

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to the canyons and valleys surrounded by

deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, aft ...

and mixed forests in eastern

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

and northern

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

. It is threatened by

habitat loss Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

. The only other large squirrel that is within its range is

Abert's squirrel Abert's squirrel or the tassel-eared squirrel (''Sciurus aberti'') is a tree squirrel in the genus ''Sciurus'' native to the southern Rocky Mountains from the United States to the northern Sierra Madre Occidental of Mexico, with concentrations fo ...

, which has ear tufts and lives in

pine A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanical Garden accep ...

forests. Although they act and look like other

gray squirrel Gray squirrel or grey squirrel may refer to several species of squirrel indigenous to North America: *The eastern gray squirrel (''Sciurus carolinensis''), from the eastern United States and southeastern Canada; introduced into the United Kingdom, I ...

s, the Arizona gray squirrel is actually more closely related to the

fox squirrel The fox squirrel (''Sciurus niger''), also known as the eastern fox squirrel or Bryant's fox squirrel, is the largest species of tree squirrel native to North America. Despite the differences in size and coloration, it is sometimes mistaken for ...

Phylogeny and description

''Sciurus arizonensis'' is a member of the order Rodentia and the family Sciuridae. It is distinguishable from ''Sciurus aberti'' by its longer flatter skull, broader rostrum, and having only one molar instead of two. ''S. arizonensis'' also has smaller ears with no tufts and a red/black stripe on the underside of their tail. Some sexual dimorphism can be seen in these squirrels, but it varies with some populations having larger males, and other populations having larger females.

Distribution and habitat

''Sciurus arizonensis'' or the Arizona gray squirrel can be found in parts of Arizona, New Mexico and Sonora, Mexico. They live in the mountains at mid-elevations in riparian habitats, usually broadleaf riparian habitats. The Arizona gray squirrel has had no recent expansion or reduction in the size of their range in New Mexico, though there has been some population decline. This is due to habitat loss and the introduction of Abert’s squirrel, which has in some cases outcompeted the Arizona gray squirrel for resources.

Diet

The Arizona gray squirrel's diet consists mainly of

pine cone A conifer cone (in formal botanical usage: strobilus, plural strobili) is a seed-bearing organ on gymnosperm plants. It is usually woody, ovoid to globular, including scales and bracts arranged around a central axis, especially in conifers a ...

acorn The acorn, or oaknut, is the nut of the oaks and their close relatives (genera ''Quercus'' and '' Lithocarpus'', in the family Fagaceae). It usually contains one seed (occasionally two seeds), enclosed in a tough, leathery shell, and borne ...

s, and other

nut Nut often refers to: * Nut (fruit), fruit composed of a hard shell and a seed, or a collective noun for dry and edible fruits or seeds * Nut (hardware), fastener used with a bolt Nut or Nuts may also refer to: Arts, entertainment, and media Co ...

s. They also eat

seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...

s and

berries A berry is a small, pulpy, and often edible fruit. Typically, berries are juicy, rounded, brightly colored, sweet, sour or tart, and do not have a stone or pit, although many pips or seeds may be present. Common examples are strawberries, raspb ...

Reproduction

Arizona gray squirrels have large variations in their diet, which has led to reproduction rates that vary year by year. Not all females breed each year, which can be seen by a lack of placental scarring. The timing of Arizona gray squirrel mating correlates with the prime time for flowers, which are a high energy food source for the energetically expensive costs of mating. Because mating is so energetically expensive, optimal reproduction timing is very important to ensure that offspring and parent will survive. This timing can differ between sexes and is largely dependent on the environmental change present in their habitat, which can often be fluctuating throughout the year and from year to year. Differences in the parental investment and a lack of food are responsible for shifts in male and female ranges. The opposite sexes have ranges that overlap with each other and during good mating conditions or season these ranges will expand and overlap more. These squirrels have been observed in mating chases with many males chasing one female. An important conservation strategy for the survival of the Arizona gray squirrel is to protect their nesting habitat. This means maintaining large trees with closed canopies that allow access to resources and protection from predators.

References

{{Taxonbar, from=Q777282

Arizona gray squirrel The Arizona gray squirrel (''Sciurus arizonensis'') is a tree squirrel, in the genus ''Sciurus'', endemic to the canyons and valleys surrounded by deciduous and mixed forests in eastern Arizona and northern Mexico. It is threatened by habi ...

Mammals of Mexico Mammals of the United States Rodents of North America Fauna of the Southwestern United States

Mammals described in 1867 Taxonomy articles created by Polbot