Sciurus carolinensis (Eastern Gray Squirrel)

Description:
The eastern gray squirrel (Sciurus carolinensis) is an arboreal rodent native to North America and introduced to parts of Europe in the 19th century, where it is considered an invasive species. It is easily recognized by its silvery-gray coat, sometimes with brownish or reddish tinges on the back, and a large, bushy tail nearly as long as its body. It has large eyes, rounded ears without tufts (unlike the red squirrel), and sharp claws ideal for climbing.

Scientific Classification:

• Kingdom: Animalia

• Phylum: Chordata

• Class: Mammalia

• Order: Rodentia

• Family: Sciuridae

• Genus: Sciurus

• Species: Sciurus carolinensis

Dimensions and Weight:
Gray squirrels measure 23–30 cm in body length, with tails adding 19–25 cm. They weigh between 400 and 700 grams. They are larger and more robust than the European red squirrel (S. vulgaris), which gives them a competitive advantage.

Habitat:
In North America, they inhabit mixed forests and urban areas. In Europe, they have rapidly adapted to parks, gardens, and deciduous woodlands. In Italy, populations exist in Piedmont, Lombardy, and Liguria, where they are gradually displacing the native red squirrel. Their adaptability allows them to thrive in human-dominated environments with easy access to food sources.

Behavior and Habits:
They are diurnal, most active in the early morning and late afternoon. While generally solitary, they tolerate other individuals in resource-rich environments. Their omnivorous diet includes seeds, acorns, nuts, fruits, fungi, buds, and occasionally eggs, insects, or nestlings. They exhibit food caching behavior, burying food to retrieve during winter. They do not hibernate but reduce activity in colder months.

Dangers, Enemies, and Threats:
In their native range, they face predation from hawks, owls, foxes, snakes, and mustelids. In Europe, however, natural predators are limited. The gray squirrel is a major threat to local biodiversity:

• Competes with the native red squirrel for food and habitat.

• Carries parapoxvirus, deadly to red squirrels but harmless to itself.

• Causes damage to forestry by stripping bark from trees, leading to ecological and economic losses.

Protected or Endangered Species:
The gray squirrel is not protected in Europe. In fact, it is listed as an invasive alien species of Union concern under EU Regulation 1143/2014. This means:

• It is illegal to breed, release, or keep them.

• Several countries, including Italy, have eradication or control programs to reduce their impact.
  The survival of the European red squirrel is closely tied to effective management of gray squirrel populations.

This funny video demonstrates the exceptional ability to balance and climb.

References_________________________________________________________________________

Bertolino, S., & Genovesi, P. (2003). Spread and attempted eradication of the grey squirrel (Sciurus carolinensis) in Italy, and consequences for the red squirrel (Sciurus vulgaris) in Eurasia. Biological conservation, 109(3), 351-358.

Abstract. In 1997, the National Wildlife Institute, in co-operation with the University of Turin, produced an action plan to eradicate the American grey squirrel from Italy, as this introduced species replaces the native red squirrel through competitive exclusion and damages trees through de-barking. The first step, a trial eradication of a small population of grey squirrels at Racconigi (Turin) to evaluate the efficiency of the removal techniques, started in May 1997. Preliminary results showed that eradication was feasible, but the project was opposed by radical animal rights groups which took the National Wildlife Institute to court in June 1997. This legal action caused a suspension of the project and led to a lengthy judicial enquiry that ended in July 2000 with the acquittal of the Institute. Nevertheless, the 3-year suspension of all actions led to a significant expansion of the grey squirrel's range and thus eradication is no longer considered practical. Therefore, in the medium to long term, grey squirrels are likely to expand through continental Eurasia. This constitutes a major threat to the survival of the red squirrel over a large portion of its distribution range and will have a significant impact on forests, with economic damage to timber crops.

Levy IH, Keller KA, Allender MC, Reich S, Whittington J. PROGNOSTIC INDICATORS FOR SURVIVAL OF ORPHANED EASTERN GRAY SQUIRRELS (SCIURUS CAROLINENSIS). J Zoo Wildl Med. 2020 Jun;51(2):275-279. doi: 10.1638/2019-0124.

Abstract. The eastern grey squirrel (EGS), Sciurus carolinensis, is a tree squirrel native to the eastern United States. This species commonly presents to wildlife medical clinics for a variety of human-related injuries including confrontations with road traffic and pet predation. The purpose of this study was to assess initial examination findings as prognostic indicators for survival in EGS. The medical record database of the University of Illinois Wildlife Medical Clinic was searched from January 2012 through December 2018 for records of EGS weighing <300 g. The squirrels were identified as survivors (individuals surviving, released, or transferred to a rehabilitator within 72 hr of intake) or nonsurvivors (individuals euthanized or dying within 72 hr of intake after receiving medical care). Presenting weight, health status, method of feeding, and singleton versus group presentation were categorically recorded for each case. The data were modeled using a series of candidate logistic regression models fitted using the generalized linear model. An information theoretical approach determined the best fit model. A total of 955 EGS were included in this study. Factors that predicted a nonsurvivor status included EGSs that presented with any health system abnormality (odds ratio [OR], 4.81; 95% confidence interval [CI], 3.34-6.72), EGSs that presented between December and May (OR, 1.60; 95% CI, 1.12-2.27) rather than between June and November, and individuals with neurologic signs (OR, 2.61; 95% CI, 1.51-4.51) compared with EGSs without neurologic signs. Despite not being included in the final model, the presence of respiratory signs (OR, 3.43; 95% CI, 2.41-4.89) and diarrhea (OR, 4.01; 95% CI, 1.59-10.09) were significantly associated with a higher likelihood of nonsurvival status. Wildlife medical clinics and rehabilitation centers may use this information by initiating more aggressive therapies or instituting distinct euthanasia protocols for EGS that present with body system abnormalities, particularly neurologic clinical signs, and those that present in the winter months.