In February, deep below the earth all over the North Shore, there are three different types of moles living very active lives. The hairy-tailed mole, the eastern mole, and the oddly-shaped star-nosed mole are remarkably similar in many aspects of their life cycle, but vary in some of their physical characteristics.
They all travel about underground in a series of amazingly complex insulated tunnel systems. And, although they live fairly isolated lives most of the year, in a couple of weeks they will be barging about looking for mates. All three types breed once a year in late winter. Once bred, the females construct a den in one of the tunnels, lining it with a variety of natural soft material. About 45 days after conception she will give birth to anywhere from 2 to 5 youngsters. The little ones come out naked, pure white, and wrinkled and need their mother's help for nursing and warmth. They mature quickly and following their mothers lead, soon learn how to forage on their own. The young female moles becoming reproductive at 10 months.
Their food sources vary, but they mostly feed on worms, grubs, and other insects. The star-nosed mole will also feed on mollusks. These little fellows are very active and require quite a bit of food each day to meet their energy needs. As a result they will forage over quite an area. Their winter tunnels are quite deep, but those they use to find food in the summer are often just below the surface. Although they tend to stay in their tunnels during the day, they will come out at night to look for food.
All three types of moles have enemies that prey upon them. Hawks will sit in a tree above a meadow and wait for them to show themselves. Owls will hear them moving in the evening and silently dive on them from above. Last spring we watched a fox hunt for them in a field in West Gloucester. He would cock his head to one side and listen for them. Then he would take a couple of steps and listen again. Suddenly he would pounce and dig furiously with his paws, dirt flying. About every third time he would come up with a helpless mole. Coyotes will do the same.
These three moles have some varying characteristics that distinguish them one from the other. The hairy-tailed mole has a pointy little nose that is shorter than the other two moles. It starts out pink, but grows to white as the mole matures. Their short thick fur is soft but a bit more coarse than the other moles and is light gray in color. And, as it's name indicates, it has a hairy tail. The adult grows to about 5 inches long with an inch-long tail. They only weigh in at a couple of ounces, but they are a bundle of energy. They are nearly blind as their eyes are covered by fur to protect them as they dig. However, they can see light changes. Their tiny ears are located below the surface of their skin, again to protect them as they dig, but they can hear.
Their front end is built for tunneling and as a result is fairly strong. Although their digits are not webbed, the palms of their front feet are very wide, acting as shovels to scoop the earth they dig.
The Eastern Mole (Scalopus aquaticus, for you Latin fans) grows to about four and one-half inches long with a one and a half inch tail. The tail is fairly short, round and scaly. Their thick soft fur can vary quite widely in color from black to almost silver. A common variation is copper. Like the hairy-tailed mole, the ears are covered with skin and the eyes are only good for detecting light.
These little fellows can really move the dirt. Their powerful front feet, unlike the hairy-tailed mole, are webbed. The muscles of their limbs are connected in a way that lets them scoop earth at an incredible speed of up to 15 feet an hour in good digging. Ken Catania, a biologist at Vanderbilt University, once observed an Eastern Mole dig over one hundred feet of tunnels in a day!
Although you would not really call these fellows social, they do not lead as solitary existence as the hairy-tailed mole. The adults will often use the same deep tunnels as others as they move to the feeding tunnels.
It is the Star-nosed Mole that has received most of the research attention. That is because they have one of the most unusual nose systems in the animal world. Unlike the other two moles, this mole is often found in wet lowland areas, is an excellent swimmer, and often eats aquatic insects and mollusks as food. They can reach up to six inches in length and weigh in at a hefty two ounces.
It is their nose that makes them really different. Right at the tip of their nose they have eleven pairs of pink, fleshy appendages that stick out in front of them. According to Catania and his fellow researcher Jon Kaas, this star-looking nose "is an extraordinary touch organ with more than 25,000 minute sensory receptors."
Their studies have revealed that "although the star is less than half an inch across, its surface is supplied with more than 100,000 large nerve fibers. By comparison, the touch receptors in the human hand are equipped with only about 17,000 of these fibers. Imagine having six times the sensitivity of your entire hand concentrated in a single finger tip."
The mole uses these appendages to find its food. If one of them touches something of interest, it squares to it and uses the bottom two to touch the object in question. A mental picture is formed and it makes a decision to eat it or not. According to Catania, "For small prey, the entire process- from first touch by the peripheral appendage to swift ingestion- takes about a fifth of a second."
What is equally remarkable is that it can smell things underwater. It sends out an air bubble to touch the object and then re-inhales the bubble. In this re-inhaling process it smells the air in the bubble! This allows it to find food underwater as it swims along.
I am always in awe of the amazing diversity of life forms that occupy the North Shore. Most of the time we are unaware of their existence and seldom see them as they go about being who they are. The more I study them, the more I understand how incredibly complex is the interdependency of our existence.
