By Bruce W. Todd, Wildlife Biologist, Division of Wildlife and Freshwater Fisheries
Most people have heard the term carnivore, meaning meat eater, or herbivore, meaning plant eater, but have you ever heard of an insectivore? These terms help classify animals into groups based on their primary feeding habits. As you may have already guessed, insectivores eat a lot of insects, which may be in larval or adult form. The insect eaters discussed in this article are called shrews.
A shrew is a small fur-covered mammal. Few people have ever seen one or even know they exist. Perhaps your recognition of the term shrew is from the title of the William Shakespeare comedy “Taming of the Shrew.” Researchers have identified many different species of shrews and at least four are known in Alabama.
Short-tailed, Southeastern, least, and pygmy shrews have all been identified in our state. Although there are differences in these four species, some similarities exist. Physical characteristics that are common to all Alabama shrews include total lengths of less than 5 1/2 inches from the tip of the snout to the tip of the tail, body weights of less than 1 ounce, and tiny ears.
There are also similarities in their life histories. All four Alabama shrews are known to be active day and night. The likely reason for extended activity is due to their voracious appetites. Some shrews have been known to eat one to three times their body weight in a 24-hour period. Shrews have life spans from one to two years in length. All of our Alabama shrews are found in damp areas or in close proximity to water. Research has shown that the short-tailed shrew requires a high level of humidity in its surroundings at all times. The required humidity may be found in moist areas on the ground or in tunnels in drier habitats.
Two of our shrews, the short-tailed and the least shrew, are classified as short-tailed shrews. The other two have longer tails in relation to their total body lengths and are in the genus Sorex. Fur color may vary within one shrew species but the following colors are common: the short-tailed shrew is lead colored; the southeastern is brown; and the pygmy and least are cinnamon.
Short-tailed shrews and Southeastern shrews are thought to use echolocation, a sensory system in which echoes of high-pitched sounds are used to determine the direction and distance of objects. The other two native shrews have also been heard making high-pitched squeaking sounds.
Shrews have some interesting characteristics. Short-tailed shrews are known to have poison in their saliva to aid in subduing prey items including salamanders, voles and young mice. Among Alabama’s shrews, only one, the least shrew, is considered social, with as many as 31 being identified in one burrow. The pygmy shrew, as its name signifies, is the smallest known mammal by weight, weighing in between 1/10 to 1/7 of an ounce.
Although relatively numerous in certain habitats, Alabama’s shrews are little known for several reasons. Their small size, burrowing and tunneling habits that keep them beneath leaf mold or underground, and the practice of being more active at night add to the inconspicuous nature of these mammals. Although we often overlook these animals, shrews are common prey items for owls, cats, dogs and snakes. You are most likely to encounter shrews while engaged in activities that bring you into their realm. Gardening, land clearing, cleaning out fence rows, or simply enjoying a forest outing may provide the occasion for you to spy one of our Alabama shrews.