Black Squirrel (Photo by Jessie Cohen)

Margie Gibson - NZP Staff Writer

The first animals that visitors to the Zoo encounter are most often not exotic species but the common, everyday variety that co-exists and even thrives as a result of human habitation. Pigeons, with their iridescent feathers gleaming in the sunlight, waddle across Olmsted Walk, picking up bits of popcorn and crusts of bread, and occasionally fleeing in great haste from a two year old determined to catch the "pretty bird." In the oaks overhead, gray squirrels scurry across the branches, hopping agilely from limb to limb, flicking their fluffy tails and chattering away. Suddenly a squirrel skirmish erupts, perhaps due to a territorial incursion, and the chase is on. Down the tree trunk, head first, two squirrels flash like lightning, until the intruder is banished to another tree. The triumphant winner scurries back to his branch in the oak, surveying the surrounding territory like a king surveying his realm.

For an idea of how varied and wide-spread the squirrel family really is, a walk through the Zoo's Small Mammal House will help visitors get acquainted with the many relatives. Within the order of Rodentia squirrels form an extensive family, Sciuridae , consisting of 50 genera and 260 species. Sciuridae comes from the Greek words skia and oura meaning "shade tail," which aptly describes their habit of holding tails over their bodies. The Chippewa Indians also recognized this peculiar trait in the name they gave to the squirrel which translated as "tail in the air."

The squirrel family includes animals ranging from the size of a mouse to some larger than cats. Squirrels inhabit every continent except Australia and Antarctica. They have developed a wide variety of body forms that equip them for life in a broad range of habitats, from semi-arid deserts and prairies to alpine regions, tropical forests, town gardens and parks. Some members of the family, such as marmots and prairie dogs, burrow underground for shelter and spend their days on the ground, while others live primarily in trees, inhabiting various elevations of the forest canopy. Nocturnal members of the family, flying squirrels, have developed a flap of skin between their legs and body, that allows them to glide through the forests rather than leap from branch to branch.

Several of the most familiar, the gray and red squirrels, Sciurus carolinensis and S. vulgaris, may be seen in enclosures behind the Small Mammal House. The red squirrels, smaller than their gray cousins, are most active early in the morning shortly after sunrise. By mid-afternoon they retreat to their nests for a snooze and emerge later in the day to feed until sundown. They have white bellies and a long, fluffy, red tail, and red fur on the upper part of the body, although the color varies greatly in different parts of Europe. Red and black ear tufts grow in winter. Body fur sheds twice each year, starting in spring with hair on the head and progressing toward the tail. The sequence reverses itself in the fall.

Red squirrels are native to coniferous and deciduous forests throughout Europe, where they feed on nuts from pines, seeds, beechnuts, and acorns. They eat most heartily in spring and summer and lighter during the remainder of the year when food supplies diminish. Although their day is centered around food-they start foraging as soon as they wake up in the morning-they tend to avoid humans and have never become a serious pest.

Long before the Romans extended their rule to Northern Europe, the red squirrel had already been woven into the indigenous culture. According to an early Germanic creation myth, at the very center of the world grew a tall and mighty ash whose branches reached over all heaven and earth, linking the two worlds. The tree was constantly threatened by its inhabitants, which included an eagle, whose flapping wings caused the wind, and a great serpent along with myriad other smaller snakes, who gnawed at its base. These opposing forces were linked by a squirrel, Ratatosk, who ran up and down the trunk, carrying insults back and forth between the eagle and snakes.

Red squirrels were holy to the Teutonic god, Donar, the thunder god, and predecessor of Thor. Donar was closely associated with the great oaks of the forests and, perhaps since he was described as having red hair, a red beard, and "beetling red eyebrows," the similarly colored red squirrel acquired special significance. To this day, the red squirrel remains a favorite character in folk stories and fairy tales throughout Europe.

In a nearby enclosure is a gray squirrel, an animal familiar to any East Coast inhabitant, and the cause of the red squirrel's decline in England. The bolder gray squirrel, because it was so appealing, was first introduced there in 1876 and was subsequently released numerous times through the first quarter of this century, but now it has almost replaced the red squirrel throughout southern England. Its habits tend to be more destructive to forests as well as gardens and lawns and have not helped endear them to the British.

A short time spent observing gray squirrels produces a number of indications that the animal has the potential to become a pest if humans attempt to share its territory. Like other members of Sciuridae, gray squirrels possess typical rodent teeth-in particular a single pair of chisel-like incisors in each jaw that grows continuously. These incisors must be worn down by use, perhaps by gnawing a hole in the hard shell of a nut to get to the succulent meat or by nibbling a hole through a wooden window sash, in a misdirected effort to find a warm winter nest.

Squirrels also have strong claws on their fingers and toes, excellent for digging holes to cache a supply of nuts. The claws, which they sink into the bark of a tree branch or trunk as they run, ensure them a firm grip as they chase nimbly through the trees.

Most types of squirrels, with their large, protruding eyes, have sharp vision and can distinguish vertical objects particularly well-a useful ability for an animal that spends much of its time in trees leaping from branch to branch. Because of strategic eye location, gray squirrels are able to see behind, overhead and underneath without turning their heads, thus giving them the ability to survey the area for any signs of danger.

Exotic, tropical squirrels, known for their bright and contrasting colors-yellows, golds, browns, oranges, black, and white-reside inside the Small Mammal House. Perhaps the most striking are the black, white, and red striped Prevost's squirrels, which are known for their great variation in color, a diversity produced by the insular nature of their habitat. Although they inhabit forests, cultivated areas and gardens in far-off southeastern Asia, they may be seen in a posture familiar to anyone who's watched a squirrel raiding a bird feeder: sitting back on their haunches while clutching a seed in their front paws. As their wild habitat has given way to greater cultivation, Prevost's squirrels have developed a taste for oil palm nuts which has brought them into conflict with plantation owners who now hunt them as pests.

Plantain squirrels, with a black stripe on each flank, cream-colored line on top, and red-tipped tail, have also come into conflict with humans. The plantain squirrel gnaws on the inner bark of rubber trees and drinks the crude rubber milk. Originally found in primary forests throughout Southeast Asia, they are now found in the bushlands, gardens, and plantations of the Malay peninsula, Sumatra, Java, and Borneo.

Both the Prevost's and plantain squirrels belong to the aptly named genus Callosciurus. Callo- comes from the Greek word for beautiful, the same word that gives us Kalorama ("beautiful view"), the name of a street in Northwest Washington that runs along the ridge overlooking Rock Creek near the Zoo.

In the large enclosure at the back of the Small Mammal House, another species of squirrel lives nearer to ground level. Lowe's squirrels, named after Sir Hugh Lowe, an English explorer who undertook a number of expeditions to southeast Asia, gnaw away at nuts found on the forest floor. The discarded shells with the neat, rounded holes testify to their healthy appetites and industrious efforts to find food.

One of the larger members of the squirrel family, the giant squirrel, can reach the size of a cat. Found from southeast Asia through the Indian subcontinent to Nepal, these squirrels live in branches at the highest reaches of trees. They use a specially-adapted digit on their paws to cling securely to the large branches. While they are able to jump 20 to 30 feet, they usually stay close to their nests, which they build near the trunk on branches sturdy enough to support their weight. Shortly after the Zoo's giant squirrel (Ratufa bicolor) arrived, keepers provided it with a large tree, thickly covered with thick, juicy-looking leaves. They were surprised when they noticed, not long afterward, that all the leaves were gone, made into a comfortable nest.

A tropical forest supports a greater diversity of squirrel species than a temperate forest, perhaps because each tropical species is able to utilize a different niche in an extremely diverse habitat. In a tropical forest, it is not unusual to find eight or nine different species of squirrels, each one exploiting the particular resources of a specific layer of the forest canopy. For example, in a Bornean forest, Prevost's squirrels and giant squirrels spend their days foraging for fruit and nuts in the upper layer of the canopy; plantain squirrels live in the middle layer, eating fruit, nuts, leaves, shoots, and insects; and Lowe's squirrels eat the bark and sap available near the forest floor. At the same time, although the diversity of species is greater than in temperate forests, density is lower because squirrels must compete among themselves and other arboreal mammals, particularly primates, for a limited food supply.

In contrast, temperate forests support only one or two squirrel species which range throughout the entire canopy as well as on the forest floor, feeding off foods distributed throughout the forest The number of individual squirrels found in temperate forests, however, is much greater than in tropical forests.

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The next time a squirrel robs the bird feeder or digs holes in a carefully-manicured lawn to store nuts for winter, don't head straight for the basement and start dusting off the Have-a-Heart traps. Take a moment first to appreciate how well the critter has adapted to such a great variety of environments around the world and reflect upon the thought that this is one animal nature created that not only can survive the human population explosion, but is thriving on it.