Black Squirrels
Even the most common critters in nature can have aspects, behaviors, or characteristics about them that I find amazing, and I am hoping you might also. The Eastern Gray Squirrel (Sciurus carolinensis) has got to be one of the most common and overlooked critters in America. They are found throughout the entire eastern half of the country, and a nearly identical cousin is found in the western half. So, the other day, when I was driving back from a presentation I had given about nature to a large group at a college, I spotted an Eastern Gray Squirrel black morph, and I thought, here is an extremely common critter with so many cool stories to tell. Black Squirrels are the melanistic variation of the Eastern Gray Squirrel. In other words, they are just a regular old Eastern Gray Squirrel, but happen to have extra melanin in their fur that makes them black. Melanin is just a pigment in the fur. So, the question is, why are they black? While we may never know why, there are some observations that we biologists can make. Black Squirrels can be found throughout the range of the Eastern Gray Squirrel, but the Black Morphs tend to be more frequent in the northern portions of its range, especially around the Great Lakes Basin. For example, the Black Morph forms the majority of the population in the Canadian province of Ontario and the state of Michigan. During the 19th and 20th centuries, the Black Morphs were introduced to many places across the eastern half of the country because people liked the way they looked. Many cities, municipalities, schools, and parks have adopted the Black Squirrel as their mascot as a symbol for their community, and some have even passed ordinances that protect the Black Squirrels. The dark fur is believed to come from a variant pigment gene. A study in 2014 showed how the pigment gene can be the determining factor in whether the squirrel will be gray or black. Another study points out that the variant pigment gene was originally found in dark morph Fox Squirrels. Fox Squirrels (Sciurus niger) are another tree squirrel found in much of North America. The pigment gene jumped from the Fox Squirrel to the Gray Squirrel after an interspecies mating occurred centuries ago. Some research shows there are some benefits to the Gray Squirrel having black fur (melanistic). One theory is that Gray Squirrels have an advantage of better concealment in deciduous (trees with leaves) forests, while Black Squirrels have the advantage of concealment in conifer (trees with needles) forests, which are found in more northern states. In addition, another study in 1989 showed that the gray morph had better concealment while sitting still, while the black morph had better concealment while in motion. The second theory for dark fur is thermoregulation. Studies show that black furred squirrels had an 18 percent lower heat loss when the outside temperatures fell below 14° F, along with a 20 percent lower metabolic rate. So, this suggests that the black coat gives an advantage in northern regions. So, what determines if a mating pair of squirrels produces black offspring? Gray Squirrels have two copies of the gray pigment gene, and Black Squirrels have either one or two copies of the black pigment gene. If a Black Squirrel has two copies of the black gene, the offspring will be jet black in color; if it has one copy, it will be a brownish-black. Only around 10 percent of the Eastern Gray Squirrel is believed to be jet black. In areas with many Black Squirrels, litters of mixed colored offspring, being gray, grayish black, and jet black are common. As you can see, there are so many interesting things to consider in even the most common of our wild critters. Now multiply this by the number of cool critters on the planet, and you can see we are surrounded by amazing and fascinating behaviors and characteristics of even the most common animals. Until next time… Stan Tekiela is an author, naturalist, and wildlife photographer who travels extensively to study and photograph wildlife. He can be followed on Instagram and Facebook. He can be contacted via his website at naturesmart.com.