Gray squirrel leaves the safety of a tree to harvest hickory nuts for the winter.
Photo: Kevin McKeon
Gray Squirrels, Our Lovable, Rascally Neighbors
By Kevin McKeon, Maine Master Naturalist
In Norse mythology, the squirrel Ratatoskr lives in the trunk of Yggdrasil, the “Tree of Life” — an immense, sacred ash tree central to the cosmos. Powerful eagles live at the treetop, and the serpent Nidhoggr dwells among the deepest roots; in between rests the universe. Ratatoskr’s function is to ferry messages around the tree, but being a mischievous imp, he derives his life-force from the discontent he nurtures by twisting the messages between eagles and Nidhoggr into insults, keeping the resultant animosity alive and thriving amid the chaos he creates.
Earth has grown more lovable real creatures among its 290 squirrel species, with 65 living in North America and four in Maine. One of Sanford’s is the eastern gray squirrel, Sciurus carolinensis. Many folks would probably argue that a bit of that rascal Ratatoskr lives within them.
Fossils found in the United States indicate that our gray squirrel is at least 250,000 years old. Sciurus comes from two Greek words meaning “shadow” and “tail,” referring to their appearance of “sitting in the shadow of their tail.” The helpless, ½-ounce newborns (usually one to four per litter, but up to eight) are naked and blind with the exception of their vibrissae — small hairs around the nose and mouth that are used like whiskers for touch. The kits, or pups, are mothered for about three months then leave, reaching maturity at 8 to 12 months. Adults grow to about a foot long and 1 pound and live to about 12 years old; a captive female lived to be more than 20.
Powerful claws, flexible toes, and double-jointed ankles combine to give our squirrel its famous tree-climbing ability; it’s one of very few mammals that can descend a tree head-first. Squirrels occupy two types of tree homes: A permanent den is often built within an existing cavity — typically a woodpecker’s former home — that gets enlarged, then insulated with leaves, moss, and twigs. Their summer home, called a drey, is a nest of leaves and twigs built on a crotch 30-45 feet above the ground. Females nest alone when pregnant, and lactating females are especially aggressive and avoided by other squirrels. During the autumn, these rodents become very active, mostly during daylight, collecting and caching nuts for their winter food. Acorns are a favorite, but hickory is the nut most prized for its high energy content and long nutritional viability, with rich amounts of fat, minerals, and vitamins.
During spring and summer, these opportunistic foragers eat small fruits, buds, flowers, roots, mushrooms, insects, small bird eggs, and carrion. An abundance of squirrel food during mast years increases squirrels’ health and populations, with females often producing two litters of larger, healthier pups those years. This gives rise to an abundance of the critters that eat squirrels, and there are many of these, attacking from the air, ground, and underground. Owls, hawks, and eagles swoop from their high perches; gray fox weasels, pine martins, bobcats, fishers, raccoons, and even cats, nab them from trees; red fox, coyotes, dogs, and the occasional snake, join others in grabbing unwary squirrels on the ground. And some of us humans have our special squirrel stew recipes.
The squirrel’s method of nut storage is surprisingly complex. It begins with selecting nuts without holes or cracks, and a keen sense of smell detects rot. Then, to prevent sprouting, which robs the nut of nutrition, they’ll often crack it open; while doing this, the squirrel covers the nut with its scent by licking it to aid in location and retrieval during winter. It’s now time to bury the nut, but if it senses it’s being watched by a blue jay or another squirrel, it will perform a “deceptive burial” technique — dig a storage hole and feign burial — then carry the nut to another area for burial, often using leaves and twigs for camouflage. Their strong sense of smell and ability to form “memory maps” — using rocks, trees, and other terrain variables — allows retrieval of up to 3,000 nuts from dozens of caches, through a foot of snow and several inches of soil. Studies show that squirrels’ brains actually swell during winter, an indication of a type of winter memory growth. (Our black-capped chickadees’ brains do that, too.)
Squirrels use two primary storage methods: Scatter hoarding and larder caching. Scattering involves the use of several caches throughout a squirrel’s habitat: The many locations result in fewer being pilfered, but remembering locations and guarding and defending is more difficult. Lardering has the rodent stashing its winter’s supply in one or two locations, making protection easier; but a dominant raiding squirrel is able to steal this sizable cache, complicating the victim’s winter survival. Many squirrels use both methods.
Some of these nuts are buried without enough sprout prevention, and several remain unretrieved due to death of the squirrel, forgetfulness, or over-storage. So, the squirrel’s storage habit results in the actual planting of tree seeds, especially during the heavy mast years. This allows for forest rejuvenation and enables the trees to migrate according to the squirrels’ migration — establishing new forests with valuable nut production for the landscape.
Squirrels have evolved several techniques for winter survival. Like most other mammals, they’ll eat like crazy during the autumn nut season, building up their body-fat storage. As the cold approaches, their dreys are deserted in favor of more easily insulated and defended tree cavities in which they’ll often huddle with other squirrels — sometimes even sharing caches — to ensure huddling warmth.
Like all rodents, squirrels have specialized teeth. Their incisors have evolved to be both self-sharpening and constantly growing, with dentin coating the back of the teeth and enamel on the front. As these critters gnaw away during their daily routines, the hard enamel rubs against the softer dentin, effectively sharpening their incisors. And since rodents have a need for sharp teeth, they’ll chew away at just about anything, including the bark on our prized fruit trees and wood on our houses!
Mast years: https://sanfordspringvalenews.com/out-in-the-woods-16/
Gray fox: https://sanfordspringvalenews.com/out-in-the-woods-the-shy-gray-fox-can-climb-trees/
Editor’s note: Did you see something unusual last time you were out in the woods? Were you puzzled or surprised by something you saw? Ask our “Out in the Woods” columnist Kevin McKeon. He’ll be happy to investigate and try to answer your questions. Email him directly at: kpm@metrocast.net
The post OUT IN THE WOODS appeared first on Sanford Springvale News.
