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American Red Squirrel
Conservation status
Least Concern (IUCN 2.3)
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Rodentia Family: Sciuridae Genus: Tamiasciurus Species: T. hudsonicus
Binomial name
Tamiasciurus hudsonicus (Erxleben, 1777)

The American Red Squirrel (Tamiasciurus hudsonicus) is one of two species of tree squirrel currently classified in the genus Tamiasciurus and known as pine squirrels (the other is the Douglas squirrel, T. douglasii). It is a medium sized (200–250g) diurnal mammal that defends a year-round exclusive territory. The diet of these tree squirrels is specialized on the seeds of conifer cones. As such, they are widely distributed across North America wherever conifers are common, except on the Pacific coasts where they are replaced by Douglas squirrels. Recently American Red Squirrel have been expanding their range to include primarily hardwood areas (Goheen et al. 2003) Image File history File links Wikitext. ... For the North American red squirrel, see American Red Squirrel. ... Image File history File links AmericanRedSquirrel. ... The conservation status of a species is an indicator of the likelihood of that species remaining extant either in the present day or the near future. ... Image File history File links Status_iucn2. ... Least Concern (LC) is an IUCN category assigned to extant species or lower taxa which have been evaluated but do not qualify for any other category. ... The IUCN Red List of Threatened Species (also known as the IUCN Red List and Red Data List), created in 1963, is the worlds most comprehensive inventory of the global conservation status of plant and animal species and can be found here. ... Scientific classification redirects here. ... For other uses, see Animal (disambiguation). ... Typical Classes See below Chordates (phylum Chordata) are a group of animals that includes the vertebrates, together with several closely related invertebrates. ... Subclasses & Infraclasses Subclass †Allotheria* Subclass Prototheria Subclass Theria Infraclass †Trituberculata Infraclass Metatheria Infraclass Eutheria For the folk-rock band see The Mammals. ... Suborders Sciuromorpha Castorimorpha Myomorpha Anomaluromorpha Hystricomorpha Rodentia is an order of mammals also known as rodents, characterised by two continuously-growing incisors in the upper and lower jaws which must be kept short by gnawing. ... Genera Many: see text. ... Species Tamiasciurus douglasii Tamiasciurus hudsonicus Pine squirrels are squirrels of the genus Tamiasciurus. ... Latin name redirects here. ... Johann Christian Polycarp Erxleben Institute of Veterinary Medicine of Georg-August-University Goettingen from 1771-1775, first and oldest academic Veterinary School in Germany Johann Christian Polycarp Erxleben (June 22, 1744 - August 19, 1777) was a German naturalist. ... Year 1777 (MDCCLXXVII) was a common year starting on Wednesday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Sunday of the 11-day slower Julian calendar). ... Species Tamiasciurus douglasii Tamiasciurus hudsonicus Pine squirrels are squirrels of the genus Tamiasciurus. ... Binomial name Tamiasciurus douglasii (Bachman, 1839) Desolation Wilderness (Sierra Nevada) The Douglas Squirrel, Tamiasciurus douglasii, is a pine squirrel found in the Pacific coastal states and provinces of North America. ... A diurnal animal (dÄ«-Å­rnÉ™l) is an animal that is active during the daytime and sleeps during the night. ... Orders & Families Cordaitales † Pinales   Pinaceae - Pine family   Araucariaceae - Araucaria family   Podocarpaceae - Yellow-wood family   Sciadopityaceae - Umbrella-pine family   Cupressaceae - Cypress family   Cephalotaxaceae - Plum-yew family   Taxaceae - Yew family Vojnovskyales † Voltziales † The conifers, division Pinophyta, are one of 13 or 14 division level taxa within the Kingdom Plantae. ... North American redirects here. ...

Nomenclature and identification

American Red Squirrels are also referred to as Pine Squirrels, North American Red Squirrels and Chickarees. They should not be confused with Eurasian red squirrels (Sciurus vulgaris); since the ranges of these species do not overlap, they are both commonly referred to as "red squirrels" in the areas where they are native. The species name hudsonicus refers to Hudson Bay, Canada, where the species was first cataloged by Erxleben in 1771 (Woods 1988). Red squirrels can be easily identified from other North American tree squirrels by their smaller size, territorial behavior and reddish fur with a white venter (under-belly; Steele 1998). Red squirrels are also much bigger than chipmunks. The Douglas squirrel is morphologically similar to the American red squirrels but has a rust venter and is restricted to the southwestern coast of British Columbia and in the Pacific Northwest of the United States. These two species do not co-occur. Binomial name Sciurus vulgaris Linnaeus, 1758 The Red Squirrel, Sciurus vulgaris, is a common European tree squirrel. ... New York Harbor, the outflow for Hudson River, is sometimes called Hudsons Bay. Hudson Bay, Canada. ... This article is about the animal. ...

Evolution/systematics

American Red Squirrels are widely distributed across North America. Their range includes most of Canada, and extends into the United States in the Rocky Mountains, the North Central and North East. There are 25 recognized sub-species of red squirrels (Steele 1998). The sub-species of red squirrel found in the southwest Yukon is T. hudsonicus petulans (Osgood, 1900) (see Steele 1998). A recent phylogeny (Mercer and Roth, 2003) suggests that squirrels as a family can be divided into five major lineages. Two of these clades are monotypic. Red squirrels (Tamiasciurus) fall within one of three remaining clades that includes flying squirrels and other tree squirrels (e.g. Sciurus). This clade is thought to have diverged from ground squirrels, chipmunks and marmots. See Mercer and Roth (2003) for details and interesting discussion of the climatic and tectonic events associated with these diversifications. In taxonomy, a subspecies is the taxon immediately subordinate to a species. ... In biology, phylogenetics (Greek: phylon = tribe, race and genetikos = relative to birth, from genesis = birth) is the study of evolutionary relatedness among various groups of organisms (e. ... A clade is a term belonging to the discipline of cladistics. ...

Status

American Red Squirrels are abundant and not of conservation concern throughout much of their range. However, an isolated population of red squirrels in Arizona has experienced considerable declines in population size. In 1987 this portion of the population was listed as Endangered. The Siberian Tiger is a subspecies of tiger that are critically endangered. ...

Food habits

American Red Squirrels are primarily granivores, but incorporate other food items into their diet opportunistically (Steele 1998). In the Yukon, extensive behavioral observations suggest that white spruce seeds (Picea glauca) comprise over 50% of a red squirrel’s diet (McAdam & Boutin unpub. data), but squirrels have also been observed eating the following: spruce buds and needles, mushrooms, willow (Salix sp.) leaves, poplar (Populus sp.) buds and catkins, bearberry (Arctostaphylos sp.) flowers and berries, and animal material such as bird eggs (Willson, et al. 2003). White spruce cones mature in late July and are harvested by red squirrels in August and September. These harvested cones are stored in a central cache and provide energy and nutrients for survival over the winter and reproduction the following spring. The fallen scales from consumed seed cones can collect in piles, called middens, more than a meter across. White spruce exhibits 2-6 year masting cycles, where a year of superabundant cone production (mast year; Kelly 1994) is followed by several years in which few cones are produced (Nienstaedt & Zasada 1990). American Red Squirrel territories may contain only one or several middens. Red (Common) Crossbill In zoology, a granivore is an animal which selectively eats the nutrient-rich seeds produced by plants, including those of gymnosperms. ... Binomial name (Moench) Voss The White Spruce (Picea glauca) is a medium-sized evergreen tree growing to 15-30 m tall, rarely to 40 m tall, and with a trunk diameter of up to 1 m. ... Species About 350, including: Salix acutifolia - Violet Willow Salix alaxensis - Alaska Willow Salix alba - White Willow Salix alpina - Alpine Willow Salix amygdaloides - Peachleaf Willow Salix arbuscula - Mountain Willow Salix arbusculoides - Littletree Willow Salix arctica - Arctic Willow Salix atrocinerea Salix aurita - Eared Willow Salix babylonica - Peking Willow Salix bakko Salix barrattiana... This article is about woody plants of the genus Populus. ... {{Taxobox this plant is sooo ugly it shoud be killed!!!!!!!!!!!!!!!!!!!!!!! ...

Nesting behavior

Nests are most commonly constructed of grass in the branches of spruce trees. Nests are also excavated from witches’ broom – abnormally dense vegetative growth resulting from a rust disease – or cavities in the trunks of spruce, poplar trees, and walnut. Kluane red squirrels rarely nest below ground. Each individual squirrel has several nests within its territory and females with young move offspring between nests. Some behavior has been reported within human dwellings using insulation as nesting fodder.

Survival

American Red Squirrels experience severe early mortality (on average only 22% survive to one year of age). The survival probability, however, increases to age three at which point it begins to decrease again. Females that survive to one year of age have a life expectancy of 2.3 years and a maximum lifespan of eight years.

Reproduction

American Red Squirrels are spontaneous ovulators (Layne 1954, Millar 1970). Females enter estrus for only one day, but venture from their territory prior to ovulation and these exploratory forays may serve to advertise their upcoming estrus. On the day of estrus, females are chased by several males in an extended mating chase. Males compete with one another for the opportunity to mate with the estrous female. Estrous females will mate with 4 – 16 males. Gestation time has been reported to range from 31 to 35 days (Lair 1985). Females can breed for the first time at one year of age but some females delay breeding until two years of age or older. Most females produce only one litter, but in some years reproduction is skipped while in other years some females attempted to breed twice. Litter sizes typically range from 1 to 5, but most litters contain 3 or 4 offspring. Offspring are pink and hairless at birth and weigh approximately 10g. Offspring grow at approximately 1.8 g/day while nursing but do not reach adult body size until 125 days of age. Offspring first emerge from their natal nest at around 42 days of age but continue to nurse until approximately 70 days Estrus (also spelled œstrus) or heat in female mammals is the period of greatest female sexual responsiveness usually coinciding with ovulation. ...

Dispersal

Juvenile American Red Squirrel must acquire a territory and midden prior to their first winter. Juveniles without a midden do not survive their first winter. Offspring can acquire a territory by competing for a vacant territory, creating a new territory or by receiving all or part of a territory from their mother. This somewhat rare (15% of litters) female behavior is referred to as breeding dispersal or bequeathal and is a form of maternal investment in offspring (Berteaux and Boutin 2000). The prevalence of this behavior is related to the abundance of food resources and the age of the mother. In some cases females will acquire additional middens prior to reproduction, which they later bequeath to their offspring (Boutin et al 2000). Offspring that do not receive a midden from their mother typically settle within 150m (3 territory diameters) from their natal territory (Berteaux and Boutin 2000).

Predators

American Red Squirrels are preyed upon by Canada Lynx (Lynx canadensis), coyote (Canis latrans), great horned owl (Bubo virginianus), northern goshawk (Accipiter gentiles), red-tailed hawk (Buteo jamaicensis), American Marten (Martes americana), fox (Vulpes vulpes), wolf (Canis lupus) and weasel (Mustela sp.). Binomial name Lynx canadensis Kerr, 1792 The Canadian Lynx (Lynx canadensis) is a close relative of the Eurasian Lynx. ... For other uses, see Coyote (disambiguation). ... Binomial name (Gmelin, 1788) Distribution Subspecies see text Synonyms Strix virginiana Gmelin, 1788 The Great Horned Owl, Bubo virginianus, is a very large owl native to North and South America. ... Binomial name Accipiter gentilis (Linnaeus, 1758) The Goshawk (Accipiter gentilis; from OE. góshafuc goose-hawk) is a medium large bird of prey in the family Accipitridae which also includes many other diurnal raptors such as eagles, buzzards and harriers. ... Binomial name (Gmelin, 1788) Synonyms Buteo borealis Buteo broealis (lapsus) The Red-tailed Hawk (Buteo jamaicensis) is a medium-sized bird of prey, one of three species colloquially known in the United States as the chickenhawk. ... Binomial name Martes americana (Turton, 1806) The American Marten (Martes americana) is a North American marten sometimes also called the Pine Marten, even though it is a separate species from the European Pine Marten. ... This article is about the animal. ... Wolf Wolf Man Mount Wolf Wolf Prizes Wolf Spider Wolf 424 Wolf 359 Wolf Point Wolf-herring Frank Wolf Friedrich Wolf Friedrich August Wolf Hugo Wolf Johannes Wolf Julius Wolf Max Franz Joseph Cornelius Wolf Maximilian Wolf Rudolf Wolf Thomas Wolf As Name Wolf Breidenbach Wolf Hirshorn Other The call... For other uses, see Weasel (disambiguation). ...

Other

The American Red Squirrel has been found in a black phase and recently, a white phase (not albino) in Alaska.^{[citation needed]}

References

• Belitsky (1996). Tamiasciurus hudsonicus. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 09 May 2006.
• Tamiasciurus hudsonicus (TSN 180166). Integrated Taxonomic Information System. Retrieved on 18 March 2006.
• Kluane Red Squirrel Project web page, Accessed on September 6, 2006.
• Berteaux, D, and S. Boutin. 2000. Breeding dispersal in female North American red squirrels. Ecology, 81: 1311-1326.
• Boutin, S., K.W. Larsen, and D. Berteaux. 200. Anticipatory parental care: Acquiring resources for offspring prior to conception. Proceedings of the Royal Society of London, Series B, 267: 2081-2085.
• Goheen, J.R., R.K. Swihart, and J.H. Robins. 2003. The anatomy of a range expansion: changes in cranial morphology and rates of energy extraction for North American red squirrels from different latitudes. Oikos, 102: 33-44.
• Kelly, D. 1994. The evolutionary ecology of mast seeding. Trends in Ecology & Evolution 9:465-470.
• Lair, H. 1985. Length of gestation in the red squirrel, Tamiasciurus hudsonicus. Journal of Mammalogy 66:809-810.
• Layne, J. N. 1954. The biology of the red squirrel Tamiasciurus hudsonicus loquax in central New York. Ecological Monographs 24:227-267.
• Mercer, J. M., and V. L. Roth. 2003. The effects of Cenozoic global change on squirrel phylogeny. Science 299:1568-1572.
• Millar, J. S. 1970. The breeding season and reproductive cycle of the western red squirrel. Canadian Journal of Zoology 48:471-473.
• Nienstaedt, H., and J. C. Zasada. 1990. Picea galuca (Moench) Voss white spruce. Pp. 165-185 in R. M. Burns and B. H. Honkala, eds. Silvics of North America. Vol. 1. Conifers. U.S. Department of Agriculture Agricultural Handbook.
• Osgood, W. H. 1900. Results of a biological reconnaissance of the Yukon River region. General account of the region. Annotated list of mammals. Annotated list of birds. North American Fauna 19:1-100.
• Steele, M. A. 1998. Tamiasciurus hudsonicus. Mammalian Species 586:1-9.
• Willson, Mary F; De Santo, Toni L; Sieving, Kathryn E (July 2003). "Red squirrels and predation risk to bird nests in northern forests". Canadian Journal of Zoology 81 (7): 1202-1208. doi:10.1139/z03-096. Retrieved on 2007-03-02. 
• Woods, S. E. J. 1980. The Squirrels of Canada. National Museums of Canada