SQUIRREL BIOLOGY
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SQUIRREL BIOLOGY

Welcome to the biology page. You can learn all about the variations of squirrels right here.

Squirrel Biology/Ecology

Anatomy

Teeth: 22 teeth. Incisors feature a hard layer of enamel that keeps teeth sharp. All food is bitten or shredded with incisors, and molars are use to grind the food.

Eyes: Squirrels eyes are positioned to allow them to see to the front, sides and from above without moving their heads. Studies show that squirrels probably do not identify or react to differences in color. Instead, their vision uses differences in brightness to separate objects or notice details.

Ears: Squirrels have an acute sense of sound although it is not their primary source of information gathering.

Sense of Smell: This is highly developed in squirrels and is very important to finding food. Through their sense of smell, squirrels can detect which nuts that have been invaded by insects. They will consume such nuts, but the do not hoard them in caches. Scent is also important in identifying and marking territory.

Fur: For adults, fur is molted twice a year, during the spring and fall. Hair on the tail and ears may only molt once a year. Variations in fur color are present among most squirrel types.

Tail: A squirrel uses it’s tail for shade, protection from the elements, balance, warmth, and communication. The tail can also assist while jumping through the air by acting as a parachute. The underside coloration and pattern can be used to age a squirrel. Black stripes are present in juveniles and not in adults.


Diet

Virtually all tree nuts are consumed by squirrels (acorn, beech, hickory, walnut, etc. Diet items also include corn, mushrooms, insects, and some carrion.



Hoarding

The squirrel’s ability to store food is a evolutionary measure to insure it’s survival. Having a surplus of food when Mast numbers are low due to productivity cycles or during winter months is obviously beneficial. Usually, the stored food is used within a year’s time. Hoarding occurs in on of two ways. Scatter hoarding is dispersing single nuts in separate areas (common in grey squirrels). Larder hoarding is caching a quantity of food at a single sight (common is red squirrels). Larder hoards are usually made close to the squirrel’s nest. Recovery rates for scatter hoard are 50%-60%.

Nests & Territory

Nests for gray squirrels are usually made of leaves (called dreys) in the summer months and in the winter months nests are located in tree cavities (called dens). Squirrels use more than one active den and the average number is three dens for each squirrel. It takes one day for a squirrel to make a leaf nest and the inside diameter is 6-8 inches. It is not uncommon for squirrels to share nests, especially in winter months.

Gray squirrel uses approximately 1.5 acres as a home territory and this area can be shared with other squirrels. They can range up to 5 miles from the nest.

Reproduction

Reproduction rates of squirrels are related to availability of food. In years when mast production is low, there will be few or no litters. On the other hand, during times when mast production is high, squirrels will produce 2 litters each year. The average litter size is 3. Weaning occurs between 8-10 weeks.



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