If you see what looks like miniature corncobs scattered in some pine needles when you are hiking the forests near the Grand Canyon, you will know that one of Arizona’s two subspecies of tassel-eared squirrels has dined in that very spot. Furthermore, you will know which one ate there without consulting a wildlife field guide.
Abert squirrels make their homes from South Rim of the Grand Canyon to the Mogollon Rim and in some of southern Arizona’s "Sky Island" mountains. Their cousins, Kaibab squirrels, live only north of the Canyon on the Kaibab Plateau, and they don’t venture anywhere else. The Abert and Kaibab squirrels were one species before the Grand Canyon gorge split their habitat, so they have a lot in common, but enough differences for each to claim their space in field guides.
Tassel-eared squirrels live in pine forests and eat the thin seeds from the inside of pinecones. The “cobs” are all that’s left after the squirrel rips apart the cone to get to the seeds. They also eat the sweet inner lining of new pine twigs, and make a mess with those, too. They leave clumps of needles, pulled off to get to the twig, and sometimes the chewed twigs. This is a last-resort food, though, providing most of the squirrels' diet during long winters.
Some of their more favored dinner preferences are acorns, mistletoe and mushrooms. An underground fungus on the roots of the pine trees provides many nutrients for the squirrels, and helps the trees as well. The fungus increases the amount of water and minerals absorbed by the tree, and serves as a high-energy food for the squirrels, helping them to stay strong enough to survive the winter. The squirrels repay the trees for food by spreading the spores to more trees.
Black-bellied and white-tailed, the Kaibab squirrels have a distinct appearance. Their backs and heads are chestnut brown, and their sides and bellies range from gray to black. The puffy silver-white tails sometimes have a light gray edging, which complements the fuzzy tufts sticking up beyond the tips of their ears. The more common Abert squirrels are lighter gray with a stripe down their backs, white undersides and gray and white tails. Aberts also sport the conspicuous long hair tufts on their ears.
These squirrels breed between late April and early June, and have up to four in a litter, but they only breed once a year. The male squirrels will chase the females for days until the one day a year she is ready to breed. Descending from the same tassel-eared ancestors as Abert squirrels, Kaibab squirrels are the perfect example of what geographic isolation can to do nature. Because of the giant gap between them, these two squirrels have evolved into entirely distinct and different subspecies. They live less than 20 miles apart, but that’s by bird. In order to get from the North Rim of the Grand Canyon to the South Rim for any kind of family reunion, a Kaibab squirrel would have to scamper several miles down to the Canyon floor, cross a cold raging river, and travel an equal number of miles up the wall on the other side of the Canyon.
Funny little squirrels, they hide from people, stay silent in the trees, and build their nests in pine trees, choosing branches 30 to 40 feet from the ground for privacy and the safety of their young. They build cozy year-round homes with twigs and cones and line them with bark, moss and feathers. The ponderosa pine tree forests on the Kaibab Plateau have been designated a National Natural Landmark because of these shy little fuzz-tails that live no where else in the world. When traveling across the plateau to the North Rim, look for the tale-tell signs of mini-corncobs, twigs chewed and spit out, and fluffy outlines high in the trees where the Kaibab squirrel sits silently and watches.