Eastern Gray Squirrel
From Wikipedia, the free encyclopedia
| Eastern Gray Squirrel | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
 |
||||||||||||||||||
| Conservation status | ||||||||||||||||||
| Scientific classification | ||||||||||||||||||
|
||||||||||||||||||
| Binomial name | ||||||||||||||||||
| Sciurus carolinensis Gmelin, 1788 |
The Eastern Gray Squirrel (Sciurus carolinensis), or the Grey Squirrel, depending on region, is a tree squirrel native to the eastern and midwestern United States and to the southerly portions of the eastern provinces of Canada. The native range of the Eastern Gray Squirrel overlaps with that of the fox squirrel (Sciurus niger), with which it is sometimes confused, although the core of the fox squirrel's range is slightly more to the west.
A prolific and adaptable species, the Eastern Gray Squirrel has been introduced to, and thrives, in several regions of the western United States. It has also been introduced to Britain, where it has spread across the country and has largely displaced the native Red Squirrel, Sciurus vulgaris. In Ireland, the red squirrel has been displaced in several eastern counties, though it still remains common in the south and west of the country.[2] There are concerns that such displacement might happen in Italy.
Contents |
[edit] Etymology
The genus, Sciurus, is derived from two Greek words, skia, meaning shadow, and oura, meaning tail. This name alludes to the squirrel sitting in the shadow of its tail.[3] The specific epithet, carolinensis, refers to the Carolinas, where the species was first recorded and where the animal is still extremely common. In the United Kingdom and Canada, it is simply referred to as the Grey Squirrel; as the species is a native of the United States, this article will use the term Eastern Gray Squirrel.[citation needed]
[edit] Description
As the name suggests, the Eastern Gray Squirrel has predominantly gray fur but it can have a reddish color. It has a white underside and a large bushy tail. Particularly in urban situations where the risk of predation is reduced, both white- and black-colored individuals are quite often found. The melanistic form, which is almost entirely black, is predominant in certain populations and in certain geographic areas, such as in large parts of southeastern Canada. There are also genetic variations within these, including individuals with black tails and black colored squirrels with white tails. The head and body length is from 23 to 30 cm, the tail from 19 to 25 cm and the adult weight varies between 400 and 600 grams.[4]
The tracks of the Eastern Gray Squirrel are difficult to distinguish from its cousins the Fox squirrel and Abert's squirrel, though the latter's range is almost entirely different from the Gray's. Like all squirrels, the Eastern Gray shows four fingers on the front feet and five on the hind feet. The hind foot-pad is often not visible in the track. When bounding or moving at speed, the front foot tracks will be behind the hind foot tracks. The bounding stride can be two or three feet long.[5]
[edit] Behavior
Like many members of the family Sciuridae, the Eastern Gray Squirrel is a scatter-hoarder; it hoards food in numerous small caches for later recovery. Some caches are quite temporary, especially those made near the site of a sudden abundance of food which can be retrieved within hours or days for re-burial in a more secure site. Others are more permanent and are not retrieved until months later. It has been estimated that each squirrel makes several thousand caches each season. The squirrels have very accurate spatial memory for the locations of these caches, and use distant and nearby landmarks to retrieve them. Smell is used once the squirrel is within a few centimeters of the cache.
The Eastern Gray Squirrels builds a type of nest, known as a drey, in the forks of trees. The drey consists mainly of dry leaves and twigs. It may also build a nest in the attic or in the exterior walls of a house, often to the consternation of the homeowner. In addition, the squirrel may inhabit a permanent tree den.[6]
The Eastern Gray Squirrel is more active during the early and late hours of the day, and tends to avoid the heat in the middle of a summer day.[6] It does not hibernate.[7]
Predators include humans, hawks, mustelids, skunks, raccoons, domestic and feral cats, snakes, owls and dogs. On occasion, a squirrel may lose part of its tail while escaping a predator.
[edit] Reproduction
The Eastern Gray Squirrel breeds twice a year, December to February and May to June, though this is slightly delayed in more northern latitudes.[6] The first litter is born in February to March, the second in June to July. There are normally two to six young in each litter, but this number can be as high as 8.
The gestation period is about 44 days.[6] The young are weaned at 7 weeks and leave the nest after 10 weeks
Eastern Gray Squirrels can start breeding as early as 5 and a half months old,[6] but usually breed for the first time at a year old.[8] It can live to be 20 years old in captivity, but in the wild it usually only lives to around 12 years old.[6]
[edit] Communication
As in most other mammals, communication among Eastern Gray Squirrel individuals involves both vocalizations and posturing. It has a quite varied repertoire of vocalizations, including a squeak similar to that of a mouse, a low pitched noise, a chatter, and a raspy "mehr mehr mehr". Other methods of communication include tail-flicking. Communications mainly used in mating season and to ward off predators
[edit] Diet
The Eastern Gray Squirrel consumes a variety of foods such as inner tree bark, various seeds and acorns, walnuts, and other nuts found in the forests.
The Eastern Gray Squirrel has a high enough tolerance for humans to inhabit residential neighborhoods and will raid bird feeders for millet, corn, and sunflower seeds.
[edit] Distribution
The Eastern Gray Squirrel is found in the eastern United States and adjacent southern Canada; New Brunswick to Manitoba, south to eastern Texas and Florida.[1] It is also introduced in the British Isles, Italy, South Africa, and Australia (extirpated by 1973).[1]
[edit] Introductions
The Eastern Gray Squirrel has been introduced to a variety of locations on the west coast of North America, including the states of Washington and Oregon and, in California, to the city of San Francisco and the peninsula area of San Mateo and Santa Clara counties, south of the city. It has become the most common squirrel in many urban and suburban habitats in the western United States north of central California. At the turn of the 20th century the Eastern Gray Squirrel was introduced into South Africa, Ireland and England. It spread rapidly across England and then became established in both Wales and parts of southern Scotland. On mainland Britain, it has almost entirely displaced the populations of native Red Squirrels. On the island of Ireland, this displacement has not been as rapid, owing to the fact there was only a single introduction in County Longford. Eastern Gray Squirrels have also been introduced to Italy, and the European Union has expressed concern that it will similarly displace the Red Squirrel from parts of the European continent.
[edit] Displacement of red squirrels
In the United Kingdom, the Eastern Gray Squirrel has few natural predators. This has aided its rapid population growth and has led to the species being classed as a pest. Measures are being devised to reduce its numbers, including one plan for famous television chefs to promote the idea of eating the squirrels.[9] In areas where relict populations of Red Squirrel survive, such as the island of Anglesey, programmes seeking to eradicate pest squirrels are in progress in an effort to allow Red Squirrel populations to recover.[10]
Although complex and controversial, the main factor in the Eastern Gray Squirrel's displacement of the Red Squirrel is thought to be its greater fitness and, hence, a competitive advantage over the Red Squirrel on all measures.[11] The Eastern Gray Squirrel tends to be larger and stronger than the Red Squirrel and has been shown to have a greater ability to store fat for winter. The squirrel can therefore compete more effectively for a larger share of the available food, resulting in relatively lower survival and breeding rates among the Red Squirrel. Parapoxvirus may also be a strongly contributing factor; Red Squirrels are fatally affected by the disease, while the Eastern Gray Squirrel is unaffected but thought to be carriers. The Red Squirrel is also less tolerant of habitat destruction and fragmentation which has led to its population decline, while the more adaptable Eastern Gray Squirrel has taken advantage and expanded.
Similar factors appear to have been at play in the Pacific region of North America, where the native American Red Squirrel has been largely displaced by the Eastern Gray Squirrel in parks and forests throughout much of the region.
Ironically, 2008 saw the rise of "fears" for the future of the Eastern Gray Squirrel, as the melanistic form (black) began to spread through the southern British population.[12] Conversely, in the UK, if a "Grey Squirrel" (Eastern Gray Squirrel) is trapped, under the Wildlife and Countryside Act 1981 it is illegal to release it or to allow it to escape into the wild; instead they should be humanely destroyed.[13]
[edit] See also
[edit] References
- ^ a b c Linzey, A.V., Koprowski, J. & NatureServe (2008). Sciurus carolinensis. 2008 IUCN Red List of Threatened Species. IUCN 2008. Retrieved on 2008-11-18.
- ^ Carey, M., Hamilton, G., Poole, A., and Lawton, C.. The Irish Squirrel Survey 2007. COFORD, Dublin – Report can be downloaded from www.coford.ie
- ^ Hamilton, H. (1990). Smith, D.. ed. Eastern Grey Squirrel. Hinterland Who's Who. ISBN 0-660-13634-1. http://www.hww.ca/hww2.asp?id=89. Retrieved on 2008-11-18.
- ^ BBC: Science and Nature, "Grey squirrel: Sciurus carolinensis"
- ^ Murie & Elbroch, Peterson Field Guide to Animal Tracks, pg. 79 (2005)
- ^ a b c d e f Lawniczak, M. (2002). "Sciurus carolinensis". Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/information/Sciurus_carolinensis.html. Retrieved on 2008-07-10.
- ^ "Grey squirrel Advisory". http://www.macclesfield.gov.uk/pdfs/grey_squirrel.pdf. Retrieved on 2008-07-10.
- ^ "Squirrels What is the life cycle of the grey squirrel?". http://www.northampton.gov.uk/site/scripts/documents_info.php?documentID=588&pageNumber=4. Retrieved on 2008-07-10.
- ^ "Jamie 'must back squirrel-eating'". BBC News. http://news.bbc.co.uk/1/hi/uk_politics/4835690.stm. Retrieved on 2007-08-22.
- ^ "Red squirrel conservation, squirrel ecology and grey squirrel management". The Friends of the Anglesey Red Squirrels. http://www.redsquirrels.info/. Retrieved on 2007-08-22.
- ^ Wauters, L. A., Gurnell, J., Martinoli, A., & Tosi, G. (2002). "Interspecific competition between native Eurasian red squirrels and alien grey squirrels: does resource partitioning occur?". Behavioral Ecology and Sociobiology 52: 332–341.
- ^ "The pack of mutant black squirrels that are giving Britain's grey population a taste of their own medicine". http://www.dailymail.co.uk/news/article-561946/The-pack-mutant-black-squirrels-giving-Britains-grey-population-taste-medicine.html.
- ^ "Defra Rural Development Service Technical Advice Note 09". http://www.lewisham.gov.uk/NR/rdonlyres/4E8EC6B7-007E-47E3-9E52-75A265182F76/0/DefraSquirrels_09.pdf.
[edit] External links
 |
Wikimedia Commons has media related to: Sciurus carolinensis |
- ARKive - Still photos and videos
- Squirrels are everywhere - Photo gallery of squirrels
- A brief history of the black squirrel at Kent State University
- Eastern Gray Squirrel Facts from Hinterland Who's Who
- An Exotic Evolution: Black Squirrels Imported in Early 1900s Gain Foothold - an article from The Washington Post
- WildlifeOnline - Natural History of Tree Squirrels
- Smithsonian Eastern Gray Squirrel article
|
|||||||||||||||||||
