Douglas squirrel

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Douglas squirrel
Douglas Squirrel DSC3742vvc.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Sciuridae
Genus: Tamiasciurus
Species:
T. douglasii
Binomial name
Tamiasciurus douglasii
(Bachman, 1839) [2]
Subspecies [3]
Tamiasciurus douglasii map.svg
Range (does not include T. d. mearnsi)

The Douglas squirrel (Tamiasciurus douglasii) is a pine squirrel found in western North America, from the Pacific Northwest (including the northwestern coastal states of the United States as well as the southwestern coast of British Columbia in Canada) to central California, with an isolated subspecies in northern Baja California, Mexico. It is sometimes known as the chickaree or pine squirrel, although these names are also used for the American red squirrel. Variant spellings of the common name are Douglas' squirrel and Douglas's squirrel. The Native Americans of Kings River called it the "Pillillooeet", in imitation of its characteristic alarm call. [4]

Description

John Muir described the Douglas squirrel as "by far the most interesting and influential of the California Sciuridæ". Adults are about 33 cm in length (including its tail, which is about 13 cm long), and weigh between 150 and 300 grams. Their appearance varies according to the season. In the summer, they are greyish or almost greenish-brown on their backs, and pale orange on the chest and belly, while legs and feet appear brown. In the winter, the coat is browner and the underside is grayer; also, the ears appear even tuftier than they do in summer. Like many squirrels, Douglas squirrels have a white eye-ring.

Anacortes Community Forest Lands (Washington) Tamiasciurus douglasii 37808.JPG
Anacortes Community Forest Lands (Washington)

Breeding

Mating can occur as early as February. Gestation is about four weeks, and the young (which are altricial) are weaned at about eight weeks of age. There may be up to six kits in a litter, though four is more usual. In the southern and lower parts of their range, they produce two litters each year.

Habitat

Douglas squirrels live in coniferous forest habitats along the Pacific Coast, from the Sierra Nevada (mountains) of California, northwards to the southwestern coast of British Columbia. Tamiasciurus douglasii prefer old-growth forests or mature second-growth forests, and some authors regard them as dependent on its presence. Mearns's squirrel is a distinctive subspecies of the Douglas squirrel that instead inhabits xeric pine forests in a small portion of Baja California. [5]

Throughout most their range, Douglas squirrels essentially replace the niche of the American red squirrel, which inhabits the coniferous forests of the rest of North America. The two species have very minimal overlap in the territory.

Douglas squirrels are territorial; in winter, each squirrel occupies a territory of about 10 000 square metres, but during the breeding season a mated pair will defend a single territory together. Douglas squirrels are active by day, throughout the year, often chattering noisily at intruders. On summer nights, they sleep in ball-shaped nests that they make in the trees, but in the winter they use holes in trees as nests. Groups of squirrels seen together during the summer are likely to be juveniles from a single litter.

Diet

Douglas squirrels mostly eat seeds of coniferous trees such as Douglas fir (Pseudotsuga menziesii), Sitka spruce (Picea sitchensis) and shore pine (Pinus contorta). They also eat the fleshy scales of green giant sequoia cones, as well as acorns, berries, mushrooms, the eggs of birds such as yellow warblers, and some fruit including strawberries and plums. Douglas squirrels are larder hoarders, [6] storing their food in a single location or 'larder' called a midden. As the squirrel peels the scales of cones to get at the seeds, the discarded scales accumulate into piles that can grow to several meters across as the same site is used by generations of squirrels.

Their predators include Pacific martens, bobcats, domestic cats, northern goshawks, and owls; although they quickly acclimatize to human presence, humans can be a threat to them, through robbing of their cone caches to find seeds for tree cultivation and through the destruction of old-growth forest. However, the squirrels' numbers appear to be unaffected by commercial thinning of forests. [7]

Pacific silver fir cone debris from Douglas squirrels feeding, North Cascades National Park Abies amabilis 28201.JPG
Pacific silver fir cone debris from Douglas squirrels feeding, North Cascades National Park

Related Research Articles

<span class="mw-page-title-main">Douglas fir</span> Species of tree

The Douglas fir is an evergreen conifer species in the pine family, Pinaceae. It is native to western North America and is also known as Douglas-fir, Douglas spruce, Oregon pine, and Columbian pine. There are three varieties: coast Douglas-fir, Rocky Mountain Douglas-fir and Mexican Douglas-fir.

<span class="mw-page-title-main">Pine squirrel</span> Genus of rodents

Pine squirrels are squirrels of the genus Tamiasciurus, in the Sciurini tribe, of the large family Sciuridae.

<span class="mw-page-title-main">Western gray squirrel</span> Species of rodent

The western gray squirrel is a tree squirrel found along the western coast of the United States and Mexico. In some places, this species has also been known as the silver-gray squirrel, the California gray squirrel, the Oregon gray squirrel, the Columbian gray squirrel and the banner-tail. There are three geographical subspecies: Sciurus griseus griseus ; S. g. nigripes ; and S. g. anthonyi.

<span class="mw-page-title-main">Coulter pine</span> Pine tree found in North America

Coulter pine, or big-cone pine, is a native of the coastal mountains of Southern California in the United States and northern Baja California in Mexico. Isolated groves are found as far north as Clearlake, California on the flanks of Mt. Konocti and Black Diamond Mines Regional Preserve. It is named after Thomas Coulter, an Irish botanist and physician. The Coulter pine produces the heaviest cone of any pine tree, up to 5 kg (11 lb) and among conifers is exceeded only by the cones of Araucaria bidwillii.

<span class="mw-page-title-main">Red squirrel</span> Species of tree squirrel common in Europe and Asia

The red squirrel or Eurasian red squirrel is a species of tree squirrel in the genus Sciurus common throughout Europe and Asia. The red squirrel is an arboreal, primarily herbivorous rodent.

<i>Abies concolor</i> Species of conifer tree

Abies concolor, the white fir, concolor fir, or Colorado fir, is a coniferous tree in the pine family Pinaceae. This tree is native to the mountains of western North America, including the Sierra Nevada and southern Rocky Mountains, and into the isolated mountain ranges of southern Arizona, New Mexico, and Northern Mexico. It naturally occurs at elevations between 900 and 3,400 metres.

<i>Pinus cembroides</i> Species of conifer

Pinus cembroides, also known as pinyon pine, Mexican pinyon, Mexican nut pine, and Mexican stone pine, is a pine in the pinyon pine group, native to western North America. It grows in areas with low levels of rainfall and its range extends southwards from Arizona, Texas and New Mexico in the United States into Mexico. It typically grows at altitudes between 1,600 and 2,400 metres. It is a small pine growing to about 20 m (66 ft) with a trunk diameter of up to 50 cm (20 in). The seeds are large and form part of the diet of the Mexican jay and Abert's squirrel. They are also collected for human consumption, being the most widely used pine nut in Mexico. This is a common pine with a wide range and the International Union for Conservation of Nature has rated its conservation status as being of "least concern".

<span class="mw-page-title-main">American red squirrel</span> Species of pine squirrel found in North America

The American red squirrel is one of three species of tree squirrels currently classified in the genus Tamiasciurus, known as the pine squirrels. The American red squirrel is variously known as the pine squirrel or piney squirrel, North American red squirrel, chickaree, boomer, or simply red squirrel. The squirrel is a small, 200–250 g (7.1–8.8 oz), diurnal mammal that defends a year-round exclusive territory. It feeds primarily on the seeds of conifer cones, and is widely distributed across much of the United States and Canada wherever conifers are common, except in the southwestern United States, where it is replaced by the formerly conspecific southwestern red squirrel, and along the Pacific coast of the United States, where its cousin the Douglas squirrel is found instead.

<span class="mw-page-title-main">Abert's squirrel</span> Species of rodent

Abert's squirrel or the tassel-eared squirrel 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 found in Arizona, New Mexico, and southwestern Colorado. It is closely associated with, and largely confined to, mature ponderosa pine forests. It is named in honor of the American naturalist John James Abert; nine subspecies are recognised. It is recognizable by its tufted ears, gray color, pale underparts and rufous patch on the lower back. The squirrel feeds on the seeds and cones of the Mexican pinyon and the ponderosa pine when they are available, but will also take fungi, buds, bark, and carrion. Breeding normally occurs in summer, with a spherical nest being built high in the canopy.

<span class="mw-page-title-main">Closed-cone conifer forest</span>

A Closed-cone conifer forest or woodland is a plant community occurring in coastal California and several offshore islands. The forests typically have a single-aged single-species conifer overstory with dense ladder fuels. Overstory species include coulter pine, monterey pine, bishop pine, shore pine, and several endemic cypresses, species which generally rely on fire to open their cones and release seeds. Closed-cone forests often grow in low nutrient and/or stressed soils, which can lead to slow growth.

<span class="mw-page-title-main">Black giant squirrel</span> Species of rodent

The Malayan or black giant squirrel is a large tree squirrel native to the Indomalayan zootope. It is found in tropical forests from northern Bangladesh, northeastern India, eastern Nepal and Bhutan, to Myanmar and southern China, south through mainland Southeast Asia, as well as several Indonesian islands and provinces.

<span class="mw-page-title-main">Caucasian squirrel</span> Species of rodent

The Caucasian squirrel or Persian squirrel, is a tree squirrel in the genus Sciurus found in temperate broadleaf and mixed forests in south-western Asia.

<span class="mw-page-title-main">Mexican fox squirrel</span> Species of rodent

The Mexican fox squirrel is a species of tree squirrel found throughout the Sierra Madre Occidental of Mexico as far south as Jalisco — and northward into the Chiricahua Mountains of southeastern Arizona, U.S.

<span class="mw-page-title-main">Gray-collared chipmunk</span> Species of rodent

The gray-collared chipmunk is a species of rodent in the family Sciuridae. It is endemic to Arizona and New Mexico in the United States.

<span class="mw-page-title-main">Allen's chipmunk</span> Species of rodent

Allen's chipmunk, also known as the shadow chipmunk, is a species of chipmunk native to the western United States. Occurring in California, Oregon, and Nevada, it is a common species of the Sierra Nevada.

<span class="mw-page-title-main">Sonoma chipmunk</span> Species of rodent

The Sonoma chipmunk is a species of rodent in the squirrel family Sciuridae. It is endemic to northwestern California in the United States. Members of Neotamias are characterized by having two premolars. N. sonomae has two subspecies: N. s. alleni and N. s. sonomae.

<span class="mw-page-title-main">Lodgepole chipmunk</span> Species of rodent

The Lodgepole chipmunk is a species of rodent in the family Sciuridae. It is found in the U.S. state of California at elevations from 1,500 to 3,000 metres. The Lodgepole chipmunk has a variety of common names including: Tahoe chipmunk, Sequoia chipmunk, Mt. Pinos chipmunk, and San Bernardino chipmunk.

<span class="mw-page-title-main">Mearns's squirrel</span> Subspecies of rodent

Mearns's squirrel is a subspecies of the Douglas squirrel endemic to Mexico. It is endangered and occurs in low densities, and is threatened by habitat loss. It is possibly also threatened by competition from the eastern gray squirrel, which was introduced to the range of Mearns's squirrel in 1946, but may not be present anymore. It is closely related to other subspecies of the Douglas squirrel, but far less is known about its behavior, which was first studied in detail in 2004. It is named for the 19th-century American naturalist Edgar Mearns.

<i>Pseudotsuga menziesii <span style="font-style:normal;">var.</span> menziesii</i> Variety of conifer

Pseudotsuga menziesii var. menziesii, commonly known as Coast Douglas-fir, Pacific Douglas-fir, Oregon pine, or Douglas spruce, is an evergreen conifer native to western North America from west-central British Columbia, Canada southward to central California, United States. In Oregon and Washington its range is continuous from the Cascades crest west to the Pacific Coast Ranges and Pacific Ocean. In California, it is found in the Klamath and California Coast Ranges as far south as the Santa Lucia Mountains with a small stand as far south as the Purisima Hills, Santa Barbara County. In the Sierra Nevada it ranges as far south as the Yosemite region. It occurs from near sea level along the coast to 1,800 metres (5,900 ft) in the California Mountains. Further inland, coast Douglas-fir is replaced by Rocky Mountain or interior Douglas-fir. Interior Douglas-fir intergrades with coast Douglas-fir in the Cascades of northern Washington and southern British Columbia.

<span class="mw-page-title-main">Southwestern red squirrel</span> Species of tree squirrel

The southwestern red squirrel or Fremont's squirrel is a species of tree squirrel endemic to high-altitude regions of the southwestern United States.

References

  1. Linzey, A. V. & Hammerson, G. (2008). "Tamiasciurus douglasii". IUCN Red List of Threatened Species . 2008. Retrieved 8 January 2009.
  2. Bachman, J. (1839) Archived January 7, 2009, at the Wayback Machine . Description of several new Species of American quadrupeds. Journal of the Academy of Natural Sciences of Philadelphia, 8, 57-74.
  3. Thorington, R.W. Jr.; Hoffmann, R.S. (2005). "Family Sciuridae". In Wilson, D.E.; Reeder, D.M (eds.). Mammal Species of the World: a taxonomic and geographic reference (3rd ed.). The Johns Hopkins University Press. pp. 754–818. ISBN   0-8018-8221-4. OCLC   26158608.
  4. Muir, John (1989). "The Douglas Squirrel". The Mountains of California. The Sierra Club. p. 173. ISBN   0-87156-663-X.
  5. Hope, Andrew G.; Malaney, Jason L.; Bell, Kayce C.; Salazar-Miralles, Fernando; Chavez, Andreas S.; Barber, Brian R.; Cook, Joseph A. (2016-07-01). "Revision of widespread red squirrels (genus: Tamiasciurus) highlights the complexity of speciation within North American forests". Molecular Phylogenetics and Evolution. 100: 170–182. doi: 10.1016/j.ympev.2016.04.014 . ISSN   1055-7903. PMID   27083861.
  6. "Gray squirrels and scatter hoarding". 24 September 2013. Retrieved 2015-11-20.
  7. Ransome, D.B.; Sullivan, T.P. (2002). "Short-term population dynamics of Glaucomys sabrinus and Tamiasciurus douglasii in commercially thinned and unthinned stands of coastal coniferous forest". Canadian Journal of Forest Research. 32: 2043–2050. doi:10.1139/x02-126.