Sciurus carolinensis , common name eastern gray squirrel or gray squirrel depending on the region, is a tree squirrel in the genus Sciurus . It comes from eastern North America, which is the most remarkable and ecological natural forest regenerator. The eastern gray squirrel in Europe is considered an invasive species.
Video Eastern gray squirrel
Distribution
Sciurus carolinensis is a native of the eastern and central western United States, and the southern part of the eastern province of Canada. The original range of the eastern gray squirrel overlaps with the fox squirrel ( Sciurus niger ), which is sometimes confusing, although the squirrel's squirrel core revolves slightly more westward. The eastern gray squirrel was found from New Brunswick to Manitoba, south to East Texas and Florida. Breeding of the eastern gray squirrel was found in Nova Scotia, but whether this population was introduced or derived from the expansion of the natural range is unknown. It has also been introduced to Ireland, England, Italy, South Africa, and Australia (where it was eradicated by 1973). Eastern gray squirrels in Europe are of concern as they evacuate some of the original squirrels there. In 1966, the squirrel was also introduced to Vancouver Island in Western Canada in the Metchosin area, and has spread widely from there. They are considered highly invasive and a threat to the local ecosystem and the original red squirrel.
Productive and adaptable species, eastern gray squirrel has also been introduced, and thrives in some areas of the western United States. A gray squirrel is an invasive species in England; it has spread throughout the country and has largely replaced the original red squirrel, S. vulgaris . In Ireland, red squirrels have been displaced in some eastern regions, although it is still common in the south and west of the country. That such a move might take place in Italy is of concern, since gray squirrels may spread to other parts of mainland Europe.
Maps Eastern gray squirrel
Etymology
The generic name, Sciurus , comes from two Greek words, skia , meaning shadow, and oura , meaning tail. The name is offensive to a squirrel sitting in the shadow of its tail. Specific nickname, carolinensis , refers to Carolinas, where the species was first recorded and where the animal is still very common. In the UK and Canada, it is simply referred to as a "gray squirrel". In the US, "east" is used to distinguish species from western gray squirrel ( Sciurus griseus ).
Description
The eastern gray squirrel has gray feathers, but can have a brownish color. It has a plain white bottom compared to the typical brownish bottom of the squirrel fox. It has a large bushy tail. Particularly in urban situations where the risk of predation is reduced, both white and black individuals are quite common. Melanistic forms, which are almost entirely black, are dominant in certain populations and in certain geographical areas, as in large parts of southeastern Canada. The melanistic squirrel seems to exhibit a higher cold tolerance than the common gray morph; when exposed to -10 Â ° C, black squirrel showed an 18% decrease in heat loss, a 20% decrease in basal metabolic rate, and an 11% increase for non-shiver thermogenesis capacity when compared to common gray morphs. These genetic variations include individuals with black tails and black squirrels with white tails. (See tree squirrels for more information on these color variations.)
The head and body length is from 23 to 30 cm (9.1 to 11.8 inches), tail from 19 to 25 cm (7.5 to 9.8 inches), and adult weight varies between 400 and 600 g (14 and 21 oz). They do not display sexual dimorphism, which means there is no gender or color difference.
The eastern gray squirrel traces are difficult to distinguish from related fox squirrels and Abert squirrels, although the latter range is almost entirely different from gray. Like all squirrels, eastern gray shows four toes on the front leg and five on the hind legs. The rear foot-pad is often not visible on the track. When running or moving with speed, the front footprints will be behind the hind legs. Running steps can be two to three meters.
The formula of the eastern gray squirrel is 1023/1013 (Upper/Lower teeth).
1.0.2.3 1.0. 1.3 ÃÆ'â € "2 = 22 total teeth.
Incisors show indeterminate growth, which means they grow consistently throughout life, and their cheek teeth show brachydont (low crowned teeth) and bunodont structures (having tubercles on the crown).
Behavior
Like many members of the Sciuridae family, eastern gray squirrels are scattering printers; it accumulates food in many small cache for later recovery. Some caches are temporary enough, especially those made near abundant food locations that can suddenly be taken within hours or days to reburial on a safer site. Others are more permanent and not taken until a few months later. Each squirrel is estimated to make several thousand caches each season. The squirrel has a very accurate spatial memory for this cache location, and uses a remote and adjacent landmark to pick it up. Odors are used in part to uncover food caches, and also find food in other squirrel storage areas. The smell is reliable when the soil is too dry or covered with snow.
Squirre sometimes use deceptive behavior to prevent other animals from taking food caches. They will pretend to bury the object if they feel that they are being watched. They do this by preparing the usual place, for example, digging a hole or widening the gap, mimicking the placement of food, while actually hiding it in their mouth, and then covering the "cache" as if they had settled the object. They also hide behind the plants while burying food or hiding them in tall trees (if their rivals are not arboreal). Such tricky repertoire shows that behavior is not innate, and implies a theory of thought of the mind.
The eastern gray squirrel is one of the very few species of mammals that can descend from the first tree. This is done by turning his legs so that the claws behind the rear paws and can grasp the bark of a tree.
The eastern gray squirrel builds a kind of nest, known as the drey, in the branches of the tree, mainly composed of dried leaves and twigs. The gloom is roughly round, about 30 ~ 60Ã, cm in diameter and is usually insulated with moss, thistledown, dry grass, and feathers to reduce heat loss. Males and females can share the same nest for a short time during the breeding season, and during the winter. Squirrel can share drey to keep warm. They can also be nested in the attic wall or the exterior of the house, where they can be considered as pests, as well as the danger of fire because of their habits of eating electrical wires. In addition, squirrels can inhabit permanent tree nests that are perforated in tree trunks or large tree branches.
The eastern gray squirrel is crepuscular, or more active during the early and late hours of the day, and tends to avoid heat in the middle of a summer day. They do not hibernate.
Predation
Predators include humans, eagles, weasels, raccoons, foxes, domestic and wild cats, snakes, owls, and dogs. In the range introduced in South Africa, it has been devoured by African harriers.
Reproduction
Eastern gray squirrels can multiply twice a year, but younger and less experienced ones usually have one litter per year in the spring. Depending on the availability of forage, older and more experienced females can breed again in the summer. In a year of abundant food, 36% of women give birth to two liters, but no one will do it in a year of bad food. Their marriage seasons are December to February and May to June, though this is slightly delayed in northern latitudes. The first garbage is born in February or March, the second in June or July, although, again, bearings may be advanced or delayed for several weeks depending on the availability of climate, temperature, and feed. In each breeding season, an average of 61 - 66% of females give birth to young. If a female fails to conceive or loses her young child to extraordinary cold weather or predation, she re-enters estrus and has trash later. 5 days before a woman enters estrus, she can draw up to 34 men from a distance of up to 500 meters. The eastern gray squirrel shows a polygynous form, in which competing males will form a hierarchy of dominance, and women will mate with many males depending on the established hierarchy.
Usually, one to four young people are born in every litter, but the largest litter size is eight. The pregnancy period is about 44 days. Young children wean about 10 weeks, although some may shrink to six weeks later in the wild. They start leaving the nest after 12 weeks, with young-born autumn often sweating with their mothers. Only one of the four squirrels survives until the age of one year, with a mortality of about 55% for the next year. The mortality rate then declines to about 30% for subsequent years until they rise sharply by the age of eight.
Rarely, Eastern gray females can enter estrus as early as five and a half months, but females are usually infertile until at least one year. Their average age of first estrus was 1.25 years. The presence of fertile men will induce ovulation in women through estrus. The male adult eastern gray is sexually between one and two years. Reproductive longevity for women appears to be more than 8 years, with 12.5 years documented in Northern Carolina. These squirrels can live up to 20 years in captivity, but in the wild live shorter lives due to the predation and challenge of their habitat. At birth, their life expectancy is 1-2 years, adults can usually live up to six years, with extraordinary people reaching the age of 12.
Growth/Ontogeny
A newborn gray squirrel weighs 13-18 grams and is entirely hairless and pink, although vibrissae is present at birth. 7-10 days postpartum, the skin begins to darken, just before the teenagers grow. The lower series teeth erupt 19-21 days postpartum, while the upper incisors erupt after 4 weeks. Cheek teeth erupt for 6 weeks. Eyes open after 21-42 days, and ears open 3-4 weeks postpartum. Weaning begins about 7 weeks postpartum, and is usually completed by week 10, followed by a loss of juvenile delinquency. Full adult body mass is achieved 8-9 months after birth.
Communications
As with most other mammals, communication between eastern gray squirrels involves both vocalization and attitude. The species has a very varied vocal repertoire, including rat-like creaks, low-pitched voices, chatter, and husky "mehr mehr mehr". Other communication methods include flickering movements of the tail and other movements, including facial expressions. Flicking the tail and calling "yoke" or "quaa" is used to counter and warn other squirrels about predators, as well as to announce when predators leave the area. Squirrel also makes a loving coo-purring voice that biologists call the "muk-uk" sound. It is used as the voice of contact between the mother and his equipment and in adulthood, by the man when he trials women during the breeding season.
The use of vocal and visual communications has proven to vary by location, based on elements such as noise pollution and the amount of open space. For example, populations living in big cities generally rely more on visual signals, because the environment is generally harder with more areas without much visual restriction. However, in heavily forested areas, vocal signals are used more frequently because relatively low noise levels and solid canopy limit visual reach.
Diet
The eastern gray squirrel eats a variety of foods, such as tree bark, tree buds, berries, many types of seeds and seeds, walnuts, and other nuts, and several types of mushrooms found in the forest, including mushroom agaric ( Amanita muscaria ). They can cause damage to trees by tearing bark and eating soft cambial tissue underneath. In Europe, sycamore ( Acer pseudoplatanus L.) and beech ( Fagus sylvatica L.) suffered the greatest damage. Squirrels also attack the garden for tomatoes, corn, strawberries, and other garden plants. Sometimes they eat tomato seeds and throw the rest away. Occasionally, eastern gray squirrels also prey on insects, frogs, small rodents including other squirrels, and small birds, their eggs, and young ones. They also eat away at the bones, horns, and turtle shells - perhaps as a rare mineral source in their normal diet.
The eastern gray squirrel has a high enough tolerance for humans to inhabit residential neighborhoods and invade feeders for millet, corn, and sunflower seeds. Some people who feed and watch birds for entertainment also deliberately feed the seeds and nuts to the squirrel for the same reason. However, in the eastern gray squirrel of England can take a significant proportion of feed additives from feeders, prevent access and reduce use by wild birds. The appeal to additional feeders can increase the predation of local birds 'nests, as the eastern gray squirrel is more likely to find food near the feeder, making it more likely to find nests, eggs and birds' nests.
Habitat
In the wild, eastern gray squirrels can be found inhabiting large areas of mature and dense forest ecosystems, typically covering 100 acres (40 hectares) of land. These forests usually contain large amounts of dense undergrowth vegetation that gives them enough food sources and lucrative dwellings. Oak-hickory hardwood forest is preferred over conifer type forest.
Eastern gray squirrels generally prefer to build their nests on big tree branches and inside hollow tree trunks. They are also known to be sheltering in the nest of stranded birds. The nest is usually coated with moss, thistledown, dry grass and feathers. It may provide and assist in the isolation of the workspace, used to reduce heat loss. The cover to the nest is usually built afterwards.
Close to human settlement, an eastern gray squirrel is found in parks and backyards of homes in urban environments and on farmland in rural surroundings.
Introduction
The eastern gray squirrel is a species introduced in various locations in western North America: in western Canada, in the southwest corner of British Columbia and to the city of Calgary, Alberta; in the United States, to the states of Washington and Oregon and, in California, to the city of San Francisco and the San Francisco Peninsula area in San Mateo and Santa Clara County, south of the city. It has become the most common squirrel in many urban and suburban habitats in western North America, from northern central California to southwest British Columbia. At the turn of the 20th century, eastern gray squirrel was introduced to South Africa, Ireland, Hawaii, Bermuda, Madeira Island, Azores, Canary Islands, Cape Verde, Italy and England.
In South Africa, though exotic, this is not usually regarded as an invasive species due to its small reach (found only in the extreme southwestern part of the Western Cape, to the north as far as the small agricultural town of Franschhoek), as well as inhabiting very urban areas and places influenced by humans, such as agricultural areas and exotic pine plantations. Here, most eat pine and pine seeds, although it will eat the original fruit and commercial as well. Even so, it can not use the natural vegetation (fynbos) found in the area, a factor that has helped limit its spread. It does not come into contact with the original squirrel because of its geographical isolation (native tree squirrels, Paraxerus cepapi , found only in the savanna region of the northeast of the country) and different habitats.
It spread rapidly throughout England and later became established in Wales and southern Scotland. In mainland Britain, almost completely evacuate the original red squirrel population. On the island of Ireland, this move is not as fast as only a single introduction made, in County Longford. The scheme has been introduced to control the population in Ireland to encourage the original red squirrel. The eastern gray squirrel has also been introduced to Italy, and the EU has expressed concern that it will also replace red squirrels from parts of continental Europe.
Red squirrel removal
In England and Ireland, eastern gray squirrels are not governed by natural predators, other than the European firs marten, which are generally absent in England and Wales. This has helped the population's rapid growth and has caused the species to be classified as a pest. Sizes are being designed to reduce the number, including a plan for celebrity chefs to promote the idea of ​​eating squirrels. In areas where the red cape breeding population survives, such as the Anglesey and Brownsea Islands, there are programs to root out the gray squirrels in an attempt to allow red squirrel populations to recover.
Though complex and controversial, the main factor in the eastern gray squirrel red squirrel is considered its greater fitness, hence the competitive advantage over red squirrels at all sizes. Eastern gray squirrels tend to be bigger and stronger than red squirrels and have been shown to have greater ability to store fat for winter. Squirrels can, therefore, compete more effectively for larger portions of available food, resulting in a relatively lower survival rate and breeding among red squirrels. Parapoxvirus can also be a contributing factor; red squirrels have long been impacted fatal by this disease, while the eastern gray squirrel is not affected, but is considered a carrier - despite how the transmitted virus has not been determined. However, some cases of red squirrels that have survived have been reported, as they have developed immunity - even though their populations are still heavily affected. Red squirrels are also less tolerant of habitat destruction and fragmentation, which has led to declining populations, while more adaptable eastern gray squirrels have taken advantage and grown.
A similar factor appears to have occurred in the Pacific region of North America, where native American red squirrels have largely been displaced by eastern gray squirrels in parks and forests in many areas.
Ironically, the "fear" for the future of the eastern gray squirrel appeared in 2008, as the melanistic (black) form began to spread through the southern English population. In Britain, if a "gray squirrel" (eastern gray squirrel) is trapped, under the 1981 Wildlife and Rural Act, it is illegal to let go or let it escape into the wild; on the contrary, it must be destroyed humanely.
East frog record of eastern gray
20 different Pleistocene fauna specimens containing S. carolinensis , were found in Florida and dated as early as the Irvingtonian period. Body size appears to have increased during the early to intermediate Holocene and then decreased to size now seen today.
As food
Gray squirrels were eaten in the past by Native Americans and their flesh is still popular among hunters in most of their North American territories. Today, it is still available for human consumption and sometimes sold in the UK. However, doctors in the United States have warned that squirrel brains should not be eaten, because of the risk that they can carry Creutzfeldt-Jakob disease.
See also
- Black squirrel, melanistic subgroup
- Western gray squirrel ( Sciurus griseus )
- Arizona gray squirrel ( Sciurus arizonensis )
- Mexican gray squirrel ( Sciurus aureogaster )
- Tommy Tucker (squirrel), the eastern gray squirrel celebrity of the 1940s
References
Further reading
- Koprowski, John L. (December 2, 1994). "Sciurus carolinensis" (PDF) . Mammalian Species . 480 (480): 1-9. doi: 10.2307/3504224. JSTORÃ, 3504224 . Retrieved March 26 2014 . < span> - A comprehensive survey paper, with extensive references
External links
- ARKive - Photos and videos are still
- Exotic Evolution: Black Squirrels Imported in the Early 1900s Gain Foothold - an article from The Washington Post
- WildlifeOnline - Natural History of Squirrels Tree
- Smithsonian Eastern Gray Squirrel article
- High definition video from a light gray squirrel, filmed in the United Kingdom
- Gray Squirrel feeds peanuts in English gardens
- Gray Squirrels, Fletcher Wildlife Garden
Source of the article : Wikipedia
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