Rhodie growers share their landscapes with all manner of animals. Many animals are fond of rhodies and their companion plants, too, although for different reasons than gardeners! We all have a clear image of deer and their vices, but there are other animals that have a huge impact on us and our plants that we don't know very well. Voles are the most common mammals in Eastern Massachusetts, but their commonness doesn't make them familiar to most people.
Voles are small, tunneling rodents, neither mice nor moles. Their closest relative here is the muskrat; up north their cousins are the lemmings. Like their relatives, voles are herbivores, voracious ones who eat nuts, seeds, bulbs, bark, roots, and stems. If you have optimistically planted tulips or crocuses only to have none survive the winter, if your glorious hostas disappear or your stunning R. impeditum suddenly wilts and comes loose in your hand when you tug it, you have voles. If the ground under your birdfeeders is spongy with tunnels, you have voles. We have made their already luscious woodlands and meadows even more desirable by building stone walls, mulching heavily with bark and woodchips, feeding the birds, and planting gardens. Massachusetts Audubon estimates prime, natural vole territory supports more than 300 per acre ! How many must live on my cultivated acres of vole heaven?
Voles and lemmings form the microtine branch of the rodent family; all other North American rodents belong to the cricetine branch. Eastern Massachusetts has two common species, the Meadow Vole, Microtus pennsylvanicus, and the Southern Red-backed Vole, Clethrionomys gapperi. The Meadow Vole is between five to six inches long, with a one to two inch tail; they have soft reddish-brown hair above, silver-tipped hair below. They have bright black, beadlike eyes and small, visible ears. In fact, they look like young muskrats. Meadow Voles live in grasslands or grassy orchards and this is the vole that ravages the tomatoes, potatoes, carrots, and beets in my garden in our community field. When I pick up the intact, leafy top of a beet and find the entire inside eaten out, I have encountered a Meadow Vole.
Red-backed voles are smaller, four to six inches, and according to my various field guides, usually have a rust-red top, buff or greyish sides, and buff-white fur below. Every vole I see around our house in the woods of Concord (and I have seen many, alive and dead) is dark grey or grey-brown with a pale belly. Red-backs sometimes have a grey phase in the Northeast, which seems to be what we have here. Red-backs do less tunneling of their own, using chipmunk and mole tunnels, but also often running above ground. There is also the Pine Vole, Microtus pinetorum, which is distinguished by its softer mole-like fur, but is much more secretive and a deeper digger, "unlikely to be seen by the nonspecialist", as the naturalists at the Massachusetts Audubon Society put it.
All three voles are active day and night, all year. The maze of tunnels in the snow under your birdfeeders is the work of voles feeding above the frozen ground under the protective snow cover. They produce three to four litters of four babies a year. Do the math and you can see that one pair of voles can turn into over one hundred (if all survive and males and females are born in equal numbers) in one year.
Moles are not rodents at all, but are confused with voles because of the similarity of name, appearance, and tunneling habit. They are related only to shrews in the Order Insectivora. As the order name says, they are insectivores! They continuously tunnel as they look for earthworms and grubs; they rarely surface as they are essentially blind and quite timid. They are 'pests' only because we resent their 'disruptive' tunneling in our lawns as they hunt down their insect prey.
We have two species of moles, the Eastern mole, Scalopus aquaticus and the Star-nosed mole, Condylura cristata; both are three to eight inches long, short-tailed, and covered with marvelous, dense grey or black fur. They look very much alike except the Star-nosed mole has an astonishing fringe of fleshy projections on its naked pink nose. Since they live underground away from predators, they do not need to reproduce rapidly and only have one litter a year.
To tell a vole from a mole, you must notice the mole's lack of visible eyes and ears, the hairless snout, and the large, specialized forefeet, with their powerful digging claws on thick legs that are turned outward (moles do a kind of breaststroke through porous soil). Voles' eyes are big and black like a mouse and they have cute little mouse-like feet. Voles are much more likely to be seen since they are unafraid of daylight and the surface of the ground, are fond of birdseed, and are not blessed with a great, cautious intellect. Since they are rapid breeders, they are the ideal mainstay of the mammalian foodchain.
The gardener should welcome the mole, even if their tunnels mess up a lovely lawn; they are allies, for the most part. Voles, on the other hand, are plant eaters. Their tastes are varied and varying. One late winter they ate every Hosta 'Honeybells' I had, leaving only thumb-sized bits of rootplate for me to replant. Since 'Honeybells' is a vigorous Hosta, in a few years I had a good supply again and the rodents haven't touched them since then!
Usually voles seem to favor expensive, unusual plants or huge ones whose loss makes a real difference in the garden, like a four foot in diameter H. 'Blue Angel' or a ten-year old, magnificent H. nigrescens. A neighbor lost dozens of Astilbe one winter. Expensive bulbs like Camassia or ornamental onions and fancy lilies are likely targets. They favor some rhododendron roots but leave most alone. They are great bark strippers during a long, bitter winter when they can't get to food in the frozen ground; from my personal observation they favor Stewartia, Euonymous, and apples.
Now I plant my crocuses only in hardware cloth boxes with tops; I put hostas in hardware cloth "pots", but too often the voles just climb over the top and eat the roots anyway. We don't have enough predators to keep their population down. House cats, which love the easily caught voles, also eat ground-nesting birds, baby snakes and young reptiles. According to Massachusetts Audubon, domestic cats do much more harm than good to the environment and should never be allowed out. When using poison traps it's hard to be properly selective (I like having some chipmunks around) and I don't want the predators we do have to eat poisoned rodents. So I curse often and remind myself to admire their efficiency and prolificness and feel grateful that they haven't eaten everything yet.