Reflections in Nature: There are 2 types of jumping mice in PA
At the beginning of December, Mary Alice and I went to a Christmas tree farm to buy our tree. While waiting to pay for the tree we selected, a young couple ahead of us were paying for the tree they had just cut down.
The young man told the owners of the tree farm that a bird’s nest was in their tree. The attendant told him that what they found was not a bird’s nest, but a kangaroo mouse nest. Although I did not say anything, I wanted to let them know that we do not have kangaroo mice in Pennsylvania.
Many years ago I was asked whether we have kangaroo mice in Pennsylvania. After doing much research, I learned that we do not have kangaroo mice here in Pennsylvania. However we do have two species of mice that can and do, on occasion, jump like a kangaroo.
They are the meadow jumping mouse and the woodland jumping mouse, which are adapted for jumping and are often referred to as kangaroo mice, but that is as far as the relationship goes.
The usual gait of the jumping mouse is a normal four-legged scamper, but if frightened or in a hurry, this mouse takes off in high arching leaps that could propel it from six to eight feet. Although these leaps give the mouse amazing speed, one great disadvantage is that the mouse cannot choose its landing place and will often fall into holes or ditches.
The meadow jumping mouse along with its close relative the woodland jumping mouse are Pennsylvania’s only hibernating mice. Just as the bear store up fat the jumping mice also store up an enormous amount of fat each fall. By October, the mice will have entered their long winter’s sleep. Their body temperature drops, circulation slows down and breathing is slight compared to their 145 breaths per minute during the summer months. They remain in hibernation until the end of April.
The exact dates of hibernation are not set by day-to-day weather conditions but by the readiness of the animal. The jumping mice seen out and about later than normal are those that have not put on enough fat to go into hibernation. In one book, I read that many jumping mice do not survive the torpor state because of insufficient fat reserves.
The woodland jumping mouse will live in either nests or burrows found in hollow logs, under roots of trees or under rocks. Although the burrows can be found anywhere, they are usually by a plant that can cover the entrance. Their nests are made from soft grasses, reeds, and leaves.
The burrows usually have multiple chambers, each one dug for a different reason. There is usually a room filled with nesting materials, such as grass, reeds, and leaves, which are used for sleeping or hibernation. Most mice have a room where they can store food for hibernation. And finally, there is in most cases a room with some nesting material for mating, and where the juveniles will be nursed.
The young are born in nests which are lined with grasses below ground. The gestation period is approximately 18 days. The female usually has two litters per year, with an average litter size of 5-8. The young are born hairless and blind, with their eyes opening at two weeks. The young will nurse for about 28 days and shortly after weaning, the young disperse, and a second litter will be born.
Some young in the first litter will breed during that first summer, however, those of the second litter do not breed until the following spring.
I believe that the nest found in the young couple’s tree at the tree farm could have been that of a deer mouse, which have been known to nest in trees or bushes.
A full-grown jumping mouse will measure 8-9 inches in length with 5-6 inches being the tail.
At night owls feed upon the jumping mice while by day they are meals for snakes, weasels, foxes, bobcats, minks, hawks. Their kangaroo leaps help in escaping, however, the fact that the mice are unavailable during hibernation is the main reason they exist.
In the wild, their average life span is less than one year.
The habitats for the meadow jumping mouse and the woodland jumping mouse are indicative of their names. Although the two species are colored similarly, the woodland jumping mouse is lighter in color. The main field identification is a white tipped tail for the woodland jumping mouse, and a brown tipped tail for the meadow jumping mouse. The woodland jumping mouse is larger than the meadow jumping mouse too.
These mice are most active at night, but can be seen during the day especially on either a cloudy or rainy day. The meadow jumping mouse is found throughout Pennsylvania while the woodland jumping mouse is more common in the northern counties and absent from the southcentral and southeastern sections of the state.
The population of both varies from year to year.
I feel cheated that I have never seen either of these jumping mice alive in the field. I have seen dead jumping mice that people have brought in for me to identify. If I ever see one of these mice alive, it will surely be as exciting as seeing a bear, big buck or a bobcat.
Bill Bower is a retired Pennsylvania Game Commission Wildlife Officer. Read his blog and listen to his podcasts on the outdoors at www.onemaningreen.com.