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Abert's squirrels (Sciurus aberti) are a North American species, found across a range of locations. Kaibab squirrels (Sciurus aberti kaibabensis) are a subspecies of Abert's squirrels, found only in one area in the United States. As these two types of squirrels have been isolated from one another for 10,000 years, they've evolved some distinct and separate characteristics.
Coat and Coloration
Abert's and Kaibab squirrels have slightly different coloration from one another. Abert's squirrels are mostly light gray in color with a black or dark gray stripe down their backs and white underparts. Kaibab squirrels have noticeable variations -- their sides and underparts are dark gray or black, their tails are white and their backs and heads are russet or chestnut brown. Both types of squirrel have longer winter coats that include large tufts or tassels on their ears.
Size and Shape
Both Abert's and Kaibab squirrels are a similar size and shape. Their heads and bodies range in length from roughly 18 to 23 inches and their tails measure an additional 7 to 10 inches. On average, they weigh around 25 ounces. Males tend to be no larger than females. These squirrels also have a similar skeletal structure, with no noticeable differences. They have short, broad skulls, with flattened frontal areas, and narrow, laterally compressed rostrums.
Habitat and Range
You can characterize Abert's and Kaibab squirrels by the habitat and geographical location in which they live. Abert's squirrels have a relatively large range and can be found in parts of Arizona, Wyoming, Utah, New Mexico and Colorado in the United States, and from Chihuahua to southern Durango in Mexico. While they most often live in ponderosa pine forests, they also can be found in mixed conifer forests, if ponderosas are present. Kaibab squirrels have a much smaller range: They only exist in the ponderosa pine forests of the northern Kaibab Plateau. As the Colorado River created the Grand Canyon, this subspecies became isolated as they couldn't cross this new and treacherous barrier.
Foraging and Feeding
Abert's and Kaibab squirrels can be characterized by the type of foods they eat. With ponderosa pines making up the main part of their diet, they both have similar eating habits. They feed on all the parts of ponderosa pines, including bark, seeds, buds and flowers, which is why they need to live amongst these trees. However, they're opportunistic feeders and will forage for fungi and other plant matter, as well as eating carrion. As they don't hibernate, they don't store large amounts of food for winter, but they may bury the odd pinecone to feed on at a later date.