Black squirrel
Black squirrels are a
Black squirrels share the same natural range as their non-melanistic counterparts. Black morphs of eastern gray squirrels occur most frequently in the northern portion of its range around the Great Lakes Basin. Conversely, black morphs of fox squirrels typically occur most frequently in the southeastern portions of the species' natural range, the southeastern United States. Although they are found more frequently in those regions, the coloration remains uncommon in most areas that these species inhabit. However, black morphs of eastern gray squirrels form the majority of the species' population in the Canadian province of Ontario, and the U.S. state of Michigan. In addition to their natural range, black morphs of eastern gray squirrels were also introduced into other areas of Canada, the United Kingdom, and the United States during the 19th and 20th centuries.
Several municipalities and post-secondary schools in the United States have adopted a black squirrel for branding purposes, using it as a symbol and/or mascot. Some municipalities that have adopted the black squirrels as a symbol for their community have also passed ordinances that discourage attempts to threaten them.
Description
The black coloration in both
Black morphs may also occur with Columbian ground squirrels, Eurasian red squirrels, Richardson's ground squirrels, and western gray squirrels, although it is far more unusual for the latter to display color polymorphism.[4][5][6][7] No association between melanism and variations in their MC1R was found in Eurasian red squirrels; with researchers suggesting that the different color variations (including black morphs) in Eurasian red squirrels, and fox squirrels being a polygenic result.[4] Melanism with Richardson's ground squirrels is due to recessive genes.[5]
Benefits of black fur
With regard to black squirrels and melanism, two major theories dominate the literature, that its frequency is the result of crypsis, and/or the result of thermoregulation.[8]
Concealment
It has been theorized that non-melanistic gray squirrels have a concealment advantage in forests dominated by
The frequency of black morph eastern gray squirrels is thought to have been once relatively common throughout the eastern gray squirrel range, although their frequency and population have dwindled since the 1700s.
Melanism in fox squirrels in the southeast portion of its natural range has also been associated with crypsis, as it inhabits forests that go through periodic burnings.[13] It has been suggested that black squirrels would be harder to detect in forests already burned, due to the blackened substrate.[13]
Thermoregulation
It has also been suggested that black morph squirrels have a considerably higher cold tolerance than gray squirrels given the color of their coat.[14] Black-coated animals were found to have 18 percent lower heat loss in temperatures below −10 °C (14 °F), a 20 percent lower metabolic rate, and a non-shivering thermogenesis capacity that is higher than a gray morph.[14] Additionally, researchers of the color morph have noted a strong negative correlation with the frequency of black squirrels and areas with high air temperature.[15]
The black coat has been suggested as a selective advantage for squirrels inhabiting the northern ranges of the species, as it helps them inhabit colder regions.
A study published by the European Journal of Ecology in 2019 on eastern fox squirrels found that the melanistic morphs of the species saw a noticeable increase in their surface temperature (fur and skin) in both sunny and cloudy weather; whereas the non-melanistic fox squirrels only saw their surface temperature increase when it was sunny with no cloud cover.[8] Its ability to gain heat in sunny and cloudy conditions is believed to be the reason why melanistic squirrels are more active during winter mornings.[17] However, the same study noted that there was no difference in metabolic heat production between the color morphs.[17]
Reproduction
Among eastern squirrels, gray mating pairs cannot produce black offspring. Gray squirrels have two copies of a gray pigment gene and black squirrels have either one or two copies of a black pigment gene. If a black squirrel has two copies of the black gene it will be jet black. If it has one copy of a black gene and one gray gene it will be brown-black.[18] Approximately nine percent of melanistic eastern gray squirrels are believed to be jet black.[19] In areas with high concentrations of black squirrels, litters of mixed-color individuals are common.[9]
Differences with non-melanistic squirrels
A study conducted in 1990 of black and gray morphs of the eastern gray squirrel concluded that there was no major difference in behavior between the morphs.
A 2019 study on fox squirrels found that there was no noticeable difference in metabolism between the different color morphs of that species.[17] However, the same study on fox squirrels found that melanistic fox squirrels were more active than their non-melanistic counterparts during the winter and spring months, with melanistic fox squirrels found to be 30 percent more active during the mornings than their non-melanistic counterparts.[23] Conversely the non-melanistic fox squirrels were more active during the autumn season.[23] It has been suggested that the black squirrel's higher heat gain for its surface temperature is the reason why they are able to be active earlier in the day and remain active longer.[17]
Distribution
Natural populations of black morph eastern gray and fox squirrels can be found in the natural ranges of both species in North America, although their frequency varies depending on the area.[4] Black fur for both species of squirrels is rare and occurs at rates of less than one percent.[24] It has been suggested that one in 10,000 eastern gray squirrels are a black morph.[2]
It has been suggested that the frequency of the black color morph in the eastern gray squirrel populations has declined since the late 1700s, especially south of the Great Lakes.[10] There is a higher frequency of the black morph in the northern portions of the eastern gray squirrel's range; which includes the southern portions of central Canada and northern United States.[1][10] In particular, large populations of black squirrels are found within the Great Lakes Basin, with a notable increase in their frequency between the 41st parallel north and the 45th parallel north.[15]
Black squirrels occur with the highest frequency in Ontario and Michigan, and are the predominant color morph found in those areas;[15] with the black morph accounting for 66 percent of squirrels documented on iNaturalist in Ontario, and 56 percent in Michigan.[15] Significant populations of black morphs are also present in the other provinces/states that surround the Great Lakes; with approximately 15 percent of the eastern grey squirrels in those regions reported to be melanistic.[15] Black squirrel populations south of the Great Lakes remain largely localized, with the frequency of black squirrels varying from one region to another.[15] Black squirrels were found to be more common in urban areas as opposed to rural areas and forests.[15] Among exurban populations of eastern gray squirrels, the black morph only occurs in high frequencies in Ontario, and northern Michigan.[20]
Conversely, black morphs of fox squirrels occur with the highest frequency in the southeastern portion of its natural range, the southeastern United States.[3] Like the eastern gray squirrels, the frequency of black fox squirrels is dependent on the area, reaching a maximum frequency of 13 percent.[3] Although they occur more frequently in the southeastern United States, large populations of black morph fox squirrels may be found in other areas of the species' natural range; including Council Bluffs, Iowa, around the Missouri River. Approximately half of the fox squirrels found in Council Bluffs are melanistic.[13] Melanistic fox squirrels in Council Bluffs have since expanded across the Missouri River to other areas in the Omaha–Council Bluffs metropolitan area; with melanistic fox squirrels now accounting for 4.6 to 7.6 percent of fox squirrels in Omaha.[13]
The Delta fox squirrel (Sciurus niger subauratus) is a subspecies of fox squirrel found in the Mississippi Alluvial Valley. There are two common phases, a glossy solid black phase and a reddish phase that lacks the white markings of the fox squirrels found in the surrounding hill country.[26]
Introduced populations
Reintroduction programs
Several populations of black morph squirrels were the result of reintroduction/re-population programs intended to reintroduce the species and/or the black morph to areas they once inhabited, but had been wiped out by human hunting and predators in previous centuries.
Black squirrels in
The present population of black eastern gray squirrels in Battle Creek, Michigan was reportedly introduced in 1915 by John Harvey Kellogg, who wanted to repopulate the area with the species after their populations were devastated in the previous centuries by predators and human hunters.[31] He reportedly received 400 eastern gray squirrels from Kent County, Michigan, including some black morphs, and released them into the community.[31] Researchers north of Battle Creek, at the Kellogg Biological Station, later trapped some black morph eastern gray squirrels in 1958 and 1962, and released them on the East Lansing campus of Michigan State University at the behest of the university's president.[31]
Black morphs were once present in Ohio, although the color morph was extirpated from the state by 1930.[21] However, an initiative to reintroduce the black morphs into the squirrel population was undertaken in 1961 by Kent State University, based in Portage County.[32] The university, in coordination from the Canadian and U.S. governments, released ten black squirrels from London, Ontario onto its campus grounds in an effort to reintroduce the black morphs into the area.[32][29] By 1964, the Record-Courier reported the number of black squirrel increased to 150.[32] Black morphs of the eastern gray squirrels have since expanded through northeastern Ohio.[21]
Introduced/non-native populations
Several populations of black morph squirrels were introduced into the area by accident. Some of these black morph populations have been embraced by their communities, although others are viewed as an invasive species to the local ecosystem.
The introduction of black squirrels in the Quad Cities occurred in the 19th century.[33] According to one story, recounted in the book The Palmers, they were first introduced on the Rock Island Arsenal by either the Palmer family or the base commander. According to the story, some of the black morphs later escaped the arsenal by jumping across ice floes on the Mississippi River when it was frozen, and populated the other areas on Rock Island.[34]
Eastern gray squirrels, including their black morphs, were introduced into British Columbia during the early 1900s.[3] The species was also later introduced into other areas of Canada to which it was not native, such as Calgary, Alberta. The majority of the eastern gray squirrels in Calgary originated as pets, or zoo animals that escaped captivity during the 1930s. As in Ontario, black eastern gray squirrels are now the predominant morph of the species found in Calgary.[35]
The black morph population in
The population of black squirrels in Massachusetts's Pioneer Valley originated from two shipments of Michigan black squirrels sent to Frank Stanley Beveridge, the founder of Stanley Park in Westfield.[9] Beveridge reportedly released the black squirrels into the park he established during the late 1940s.[9] The population of black squirrels has since spread throughout the Pioneer Valley, with large populations existing in Amherst and Westfield.[9] During this same period, black squirrels from Canada were also released at parks in Princeton, New Jersey.[38]
Black morphs of eastern gray squirrels are also present in the United Kingdom. The black squirrel population in the UK originates from black morphs brought over from North America, as opposed to a mutation that occurred with the existing population of non-melanistic eastern gray squirrels.[4][39] However, how the species was introduced into the country's ecosystem remains undetermined. Some suggest the black morph population originated from squirrels released into the wild in the 19th century, while others assert the population originated from black morphs in zoos that escaped captivity.[39][40] The first black squirrel to be recorded in the wild in the United Kingdom was in 1912, in Woburn, Bedfordshire.[41] By 2009, the black morph accounted for nearly half of all squirrels in Cambridgeshire and in other areas of England, including Hertfordshire and Bedfordshire.[42][43] There are an estimated 25,000 black morphs squirrels in the East of England in 2009.[39] However, as eastern gray squirrels (both non-melanistic and black morphs) threaten the local Eurasian red squirrel population, local authorities have begun to regulate and control the spread of the species in parts of England.[40]
In culture
Black squirrels have been adopted by several cities and post-secondary institutions in the United States for the purposes of public relations branding, often making the black morphs a mascot.[44]
The city of Marysville, Kansas, adopted the black morph squirrels as an official mascot of the city in 1972,[45][46] and the "Black Squirrel Song" becoming the town's official anthem in 1987.[37] The same legislation that made it an official mascot provided the "mascots" the freedom to trespass on all city property, "immunity" from all traffic regulations, and the "first pick of all black walnuts growing within the city".[45] Marysville is one of several communities in the United States that have enacted specific legislation to protect the black morph populations, given their low frequency south of the Great Lakes.[47] Other cities that provide legal protection for black squirrels include Council Bluffs, Iowa; which enacted an ordinance that discourages attempts to threaten them.[47]
Several universities also use a black squirrel as an "unofficial" mascot or symbol for their institutions for public relations purposes. Post-secondary institutions typically adopt the black squirrel as an informal mascot for branding purposes, in an effort to further their recognition and visibility and to present an image of a "fun college campus".
Literature
Black squirrels are major characters in British author
In Celtic folklore, black squirrels were associated with magic, occult knowledge, and the otherworld.[56]
Black squirrels inhabit the forest of Mirkwood in the legendarium of J. R. R. Tolkien.[57]
See also
- Black cat
- Black panther
- Black tiger
- Black wolf
- White squirrel
References
- ^ a b c d "Interbreeding turned grey squirrels black - study". aru.ac.uk. Anglia Ruskin University. 13 August 2019. Retrieved 6 May 2020.
- ^ a b c d Solly, Meilan (16 August 2019). "Interspecies Breeding Is Responsible for Some Squirrels' Black Coloring". Smithsonian Magazine. Smithsonian Institution.
- ^ PMID 31296164.
- ^ PMID 24534267.
- ^ a b Michener, Gail R. "Species Description of Richardson's Ground Squirrels (also known as gophers)". research.uleth.ca. University of Lethbridge. Retrieved 8 December 2021.
- ^ Moore, Sarah (26 July 2021). "Rare black ground squirrel spotted in Banff alpine area". www.cbc.ca. Canadian Broadcasting Corporation. Retrieved 1 September 2021.
- ^ Bergamin, Alessandra (20 February 2014). "Are Black Squirrels Common in the Bay Area?". baynature.org. Bay Nature Institute. Retrieved 7 May 2020.
- ^ a b Ciurej et al. 2019, p. 79.
- ^ a b c d e f g h "Region's black squirrels offer genetics lesson". MassLive Media, Massachusetts. Advance Publications Inc. 9 February 2009. Retrieved 28 May 2009.
- ^ a b c Gustafson & VanDruff 1990, p. 186.
- ^ Boughton, Kathryn (13 November 2012). "You're Not Seeing Things, Squirrels 'Morphing' From Gray to Black". www.ctinsider.com. CT Insider. Retrieved 2 September 2022.
- ^ Gustafson & VanDruff 1990, p. 190.
- ^ a b c d Ciurej et al. 2019, p. 80.
- ^ a b Lawniczk, Mara Katharine (2002). "Sciurus carolinensis". animaldiversity.org. University of Michigan. Retrieved 7 May 2020.
- ^ PMID 32076531.
- ^ Moodie, Jim (11 December 2015). "Sudbury Accent: Squirrels back in black". The Sudbury Star. Postmedia Network Inc. Retrieved 7 May 2020.
- ^ a b c d Ciurej et al. 2019, p. 84.
- PMID 19643815.
- ^ a b Bohls & Koehnle 2017, p. 233.
- ^ a b c Gustafson & VanDruff 1990, p. 191.
- ^ a b c Bohls & Koehnle 2017, p. 226.
- ^ a b Bohls & Koehnle 2017, p. 234.
- ^ a b Ciurej et al. 2019, p. 82.
- ^ Letzter, Rafi (14 August 2019). "Scientists Figure Out Why There Are Black Squirrels All Over the United States". Live Science. Purch Group. Retrieved 2 June 2020.
- ISSN 0003-0031. Retrieved 4 March 2024.
- ^ Godwin, David; Hamrick, Rick. "Mississippi Squirrel Species". Mississippi Wildlife Fisheries & Parks.
- ^ a b c Fahrenthold, David A. (19 May 2005). "An Exotic Evolution". The Washington Post. Nash Holdings. Retrieved 7 May 2020.
- ^ Kwong, Matt (12 July 2018). "Canadian rodents ended up overrunning Washington". CBC News. Canadian Broadcasting Corporation. Retrieved 7 May 2020.
- ^ ISBN 978-0-8117-0585-1.
- ISBN 0-8018-8403-9.
- ^ a b c Buckley, Nick (14 October 2019). "Why are there so many black squirrels in Battle Creek". Battle Creek Enquirer. Gannett. Retrieved 7 May 2020.
- ^ a b c d Peters, Benjamin (11 July 2019). "Why are Kent's black squirrels spreading across Northeast Ohio?". The Plain Dealer. Advance Publications Inc. Retrieved 7 May 2020.
- ^ Sago, Renata (14 October 2014). "Are Black Squirrels Native to the Quad Cities?". www.wvik.org. National Public Radio. Retrieved 7 May 2020.
- ^ "Black-squirrel population unique here". qconline.com. Moline Dispatch Publishing Company, L.L.C. 9 February 1998. Archived from the original on 7 September 2012. Retrieved 23 April 2009.
- ^ Fisher, Chris (15 April 2017). "Calgary critters: check out who calls your neighbourhood home". CBC News. Canadian Broadcasting Corporation. Retrieved 7 May 2020.
- ^ a b Anderson, Phil (27 October 2016). "Marysville to unveil 21 black squirrel statues during 44th annual celebration on Friday night". The Topeka Capital-Journal. Retrieved 7 May 2020.
- ^ a b Corrigan 2019, p. 75.
- ^ Maynard, W. Barksdale (3 December 2014). "Rise of the Rascally Squirrel". Princeton Alumni Week. Princeton University. Retrieved 7 May 2020.
- ^ a b c "Black squirrels set to dominate". BBC Inside Out. British Broadcasting Corporation. 20 January 2009. Retrieved 13 February 2009.
- ^ a b Stokstad, Erik (9 June 2016). "The bloody battle to save the red squirrel". Science. American Association for the Advancement of Science. Retrieved 7 May 2020.
- ^ "Interbreeding turned grey squirrels black: study". phys.org. 13 August 2019. Retrieved 2 June 2020.
- ^ Barkham, Patrick (13 August 2019). "Black squirrel 'super' species? No, just a darker shade of grey". www.msn.com. Microsoft. Retrieved 7 May 2020.
- ^ Lister, David; Smith, Lewis (26 April 2008). "Squirrel wars: reds, greys and blacks battle for supremacy". The Times. Retrieved 7 May 2020.
- ^ Corrigan 2019, p. 76.
- ^ a b "Black Squirrels City". skyways.lib.ks.us. Marysville Chamber of Commerce. 2008. Archived from the original on 4 March 2009. Retrieved 23 April 2009.
- ^ "Black Squirrels on Parade". www.visitmarysvilleks.org. City of Marysville. Retrieved 7 May 2020.
- ^ a b Corrigan 2019, p. 74.
- ^ a b Corrigan 2019, p. 78.
- ^ "A brief history of the black squirrel at Kent State University". www.registrars.kent.edu. Kent State University. 1993. Archived from the original on 10 April 2010. Retrieved 19 July 2008.
- ^ "Black Squirrel Festival". www.kent.edu. Kent State University. Retrieved 7 May 2020.
- ^ Corrigan 2019, p. 77.
- ^ "Black Squirrel Books". www.kentstateuniversitypress.com. Kent state University. Retrieved 7 May 2020.
- ^ "Logo History". www.haverfordathletics.com. Haverford College. 2009. Retrieved 23 April 2009.
- ^ Jarvis, Robin. "The Deptford Histories - The Oaken Throne". Robinjarvis.com. Retrieved 17 March 2021.
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- ^ "Black Squirrel Meaning: Symbolism & Spiritual Meaning".
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Further reading
- Bohls, Patricia; Koehnle, Thomas J. (2017). "Responses of Eastern Gray Squirrels (Sciurus carolinensis) to Predator Calls and Their Modulation by Coat Color". American Midland Naturalist. 178 (2): 226–236. .
- Ciurej, Amanda K.; Oblander, Ashley; Swift, Andrew W.; Wilson, James A. (2019). "Melanism as a potential thermal benefit in eastern fox squirrels (Sciurus niger)". European Journal of Ecology. 5 (2): 79–87. .
- Corrigan, Don H. (2019). Nuts About Squirrels: The Rodent That Conquered Popular Culture. McFarland. ISBN 978-1-4766-3635-1.
- Gustafson, Eric J.; VanDruff, Larry (1990). "Behavior of black and gray morphs of Sciurus carolinensis in an urban environment". American Midland Naturalist. 123 (1): 186–192. JSTOR 2425772.
External links
- Media related to Melanism in squirrels at Wikimedia Commons