2007-07-14 / Columnists

Nature Notes

Squirrels, Chipmunks Becoming as Common as Island's Tourists
By Patricia Martin

The other day I was talking to a friend, who mentioned that this year there seemed to be an inordinately large number of squirrels, both red and gray, and Eastern chipmunks. There are lots of squirrels and chipmunks visible around town and in the woods. In part, it might be because of the dry year, which has caused the undergrowth to be thinner and so you can see more clearly through the woods, but I think that this is only part of the story.

Most people probably readily recognize these furry creatures. The Eastern gray squirrel (Sciurus carolinensis) is about 17 to 20 inches long, with a tail that is about half its total length. Generally the squirrel has a distinct grayish cast caused by silvery tips on the hairs. Underparts are yellowish white and the tail is bushy. There is a white eye ring and white patch behind each ear. On the Island and in the Great Lakes region, it's not uncommon to see a melanistic phase of the gray squirrel that appears almost totally black and is often referred to as a "black squirrel," though species-wise, it's still a gray.

The red squirrel, sometimes called the pine squirrel (Tamiascuiurus hudsonicus), is about a third smaller than the gray, with a total length of 11 to 14 inches and a tail length of four to 5.25 inches. It only weighs about a quarter to half a pound. In the summer, this squirrel has a dorsal band of pale reddish gray to reddish brown hair running along the back, from its head to the tip of its tail. The sides appear olive gray and are separated from its whitish underbelly by a narrow black line. There is a white ring around the eye. In the winter, the reddish back is brighter, although the black side line is less distinct.

Chipmunk Chipmunk The Eastern chipmunk (Tamias striatus) is the smallest of this trio, being less than 10 inches in total length with a tail about 2.6 to 4.3 inches long, and weighing in at 2.5 to four ounces. The back of the chipmunk is grayish brown to reddish brown with an obvious red patch on the rump. Its underparts are white and there are five dark strips along the back and sides. The longest of these runs down the midline. Between the paired dark lateral stripes is a narrow band of white.

Squirrel Squirrel Squirrels and chipmunks are rodents, with the typical pair of large, curving incisors and the upper and lower jaws, and a sizable gap between the incisors and the cheek teeth. The incisors continue to grow throughout the rodent's life and they're constantly sharpened by gnawing. The front of the incisors is coated with orange enamel and the rear is softer dentine. This allows the teeth to be continually sharpened to a chisel-like edge.

As with many mammals, the size of the population is dependent on food availability, predation, and the severity of the winter. The last few years, winters have been mild and the food has been in good supply. Normally the gray squirrel and the Eastern chipmunk produce two litters of young each year, the first in the early spring and the other in midsummer. The litters consist of usually two to four or five young. Red squirrels, on the other hand, if they're living in the north, usually produce only one litter and skip the midsummer litter. Recently, a study done by Michigan State Professor Andrew McAdams showed an interesting relationship between the production of cones on spruce trees and the number of litters of red squirrels produced.

Spruce trees have evolved a phenomenon called "masting." In most years, the trees will only produce a few cones, making food in short supply for squirrels, especially the red, as it's their favorite food. They live on the spruce seeds during the winter, while gray squirrels and chipmunks go into a semihibernative state in the winter. Unpredictably, in a given year, every spruce tree in a given area will produce a bumper crop. It has been shown that in these years of great spruce tree production, the red squirrels will produce a second litter. It will be interesting to note, in this year of numerous squirrels, if the white spruce has produced an abundance of cones.

It doesn't seem to me that there is a lack of predators for our furry rodents. Everything from owls to hawks and eagles eat them. So do fishers, martens, mink, coyotes, red foxes, and yes, cats and dogs.

The discussion I mentioned earlier with my friend finally wound around to wondering about which of these little rodents caused the most damage. Her daughter had told her of a chipmunk that was found chewing the lining out of her aunt's golf shoe. Thinking back, I remembered the time in the fall when I was off the Island, and a neighbor called and let me know that they had seen a squirrel in my house. We still don't know how it got in, but it had knocked many small items off shelves and had built itself a nest. Luckily for me, it had nested in a box of facial tissue, and not in a pillow or mattress. By the way, it was the black phase of the gray squirrel. I might also mention several times when a squirrel has made an unfortunate contact with some of Edison Sault Electric Company's equipment on the Island, resulting in some interrupted power supply.

Squirrels and chipmunks also cause damage to gardens. Because of their adaptable diet, squirrels will take their toll on berries, fruits, corn, newly planted seeds, tender plants or plant parts, and flower bulbs. They also, of course, eat nuts and have been known to dine on mushrooms, insects, and even eggs. Chipmunks delight in digging up bulbs, seeds, and entire plants. They've been known to molest cornstalks and peel bark from young trees. According to one of my favorite books, "Bug, Slugs, & Other Thugs" by Rhonda Massingham Hart, there are a number of repellents that may keep squirrels and chipmunks out of the garden. Dried blood meal placed around the border of the garden will help keep them away (and rabbits, too). My problem with it is that my dog likes to lick it up. A spray made of pureed and strained hot peppers in water with a tablespoon of liquid soap is supposed to keep the squirrels away. Having dogs or cats can also help, and some people even scatter dog or cat hair around plants to keep the furry rodents away. Some companies are producing ultrasonic noise devices, which emit unpleasant sound waves within the hearing range of squirrels and other rodents. Squirrels can also be excluded from the garden by chicken wire or screening placed over planted seeds or made into cages over transplants.

I'm sure many of you have some of your own stories about squirrels. If you have a tale (or tail) or an opinion about which of these do the most damage, let me know, as I'm taking an informal poll. Feel free to vote for red squirrel, gray squirrel (which includes the black), or Eastern chipmunk. I'll let you know the results in an upcoming column.

Trish Martin is a yeararound resident of Mackinac Island, has earned a master's degree in botany from Central Michigan University, and owns Bogan Lane Inn.

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