Saturday, December 19, 2009

Adirondack Lemmings

When I think of lemmings, the first thing that comes to mind is Gary Larson’s FarSide cartoon with all the rodents rushing towards the edge of a cliff, one wearing an inner tube. What I don’t immediately think of is the fact that we have lemmings right here in our own back yards. Yes, Virginia, there are lemmings in the Adirondacks.

Admittedly, our lemmings are a different genus that those of movie and cartoon fame. Adirondack lemmings come in two flavors: the southern bog lemming, Synaptomys cooperi, and the northern bog lemming, Synaptomys borealis. They are small rodents, related to, and looking an awful lot like, voles: chunky bodies, beady little eyes, smallish rounded ears that are mostly hidden by shaggy fur. They have short tails and grooved upper incisors, which are the two characteristics that distinguish them from the other voles that live in our mountains.

But before I get into too much detail about these little guys, I’d like to first address the idea that lemmings, obeying some preordained internal message, make massive migrations to the sea and throw themselves into the churning water at the base of towering cliffs, a furry mass-suicide. Don’t you believe it. This whole lemming suicide thing (there’s no better word for it) is entirely fictitious and we can thank Disney for its creation.

Those of us of a certain generation grew up with “The Wonderful World of Disney” and “Mutual of Omaha’s Wild Kingdom” as mainstays of our Sunday nights. Looking back on many of the nature programs of that era, it’s kind of amazing what we swallowed as fact. In 1958 (before my time), Disney came out with a movie titled “White Wilderness,” a documentary about some of the animals in the far north. The lemming section was filmed in Alberta, a landlocked portion of Canada. Not only is there no sea in Alberta, there are also no lemmings. So, the film crew bought pet lemmings from nearby Inuit kids, and using fancy camera angles and other tricks of the trade, they made these few animals look like thousands. Then, and here’s the kicker, they put the animals on a snow-covered turntable that flung them off the cliff and into the water (a river, not the sea) below. With the narrator using a dramatic voice and just the right words, the stage for the birth of a myth: lemming suicides.

Fifty-one years later, people still believe it.

As stated above, the lemmings depicted in this erroneous film are a different genus from our bog lemmings, but I just wanted to clear the air ahead of time that lemmings do not make massive migrations to the sea to commit suicide. What we do see, however, in lemming populations all over the world, regardless of species, is dramatic rises and falls in the population. For a few years the numbers climb, and then suddenly they plummet, taking the species to near-extinction, only to start climbing again before they bottom out. This could be a reflection of a predator-prey cycle (more prey means more predators; more predators means fewer prey; fewer prey mean fewer predators; fewer predators means more prey, and so on), or it could be because as the rodent’s numbers increase, they consume more food, and soon food becomes scarce. Then the population declines due to lack of food, food supplies begin to increase, leading once more to an inevitable rise in the rodent population. Either way, it’s a cycle and one that is a natural part of population dynamics everywhere.

Back to our bog lemmings. Both the northern and southern have an historic presence in the Adirondacks, but according to D. Andrew Saunders’ Adirondack Mammals, the northern has only been verified recently (in the ‘80s) by one specimen from Whiteface Mountain. Since, based on this evidence, the northern is not that common here, I’m going to focus strictly on the southern.

The big burning questions is: do bog lemmings really live in bogs? The simple answer is not so much in the Adirondacks. Our southern bog lemmings (henceforth referred to as “SBL”) are found mostly in deciduous and mixed deciduous-conifer forests, hanging out in grassy openings and areas where tall sedges, ferns and shrubs grow, providing good cover and easily accessible food. (I caught one once, back in the summer of ’95, just about a mile from the VIC. It was a momentous event in my graduate advisor’s eyes, and he added the animal to his collection of study skins.) Like other small mammals, the SBL creates a maze of connected trails and tunnels to navigate through its chosen home, the former above ground, the latter just below the surface. A distinguishing part of the SBL’s home is the globular nest it builds of various plant fibers. In the summer these nests are found tucked away on top of the ground, sometimes near stumps, other times hidden in clumps of sedges. In the winter, though, the lemmings build their nests below ground, in a side chamber off their tunnel systems.

One of the things I find fascinating about SBLs in the fact that their scats are green, like goose scat! And like geese, this is because lemmings are herbivores that eat a lot of green material (as opposed to lots of twigs and nuts). Grasses and other green leaves make up the bulk of their diet, although mosses, fungi, fruits and roots are also consumed. I even read that sometimes they’ll eat invertebrates, like snails and slugs, but these are a very minor part of the diet.

SBLs are primarily night-active. This is most likely an adaptation to avoid run-ins with potential predators. Snakes, raptors, weasels, raccoons, foxes and coyotes are all potentially after a nice lemming snack. By moving about mostly at night, the lemming can somewhat hide its movements. On the other hand, many of these predators are well-adapted to hunting after dark. All’s fair in a dog-eat-dog world.

Are you likely to encounter a southern bog lemming in your daily travels around the Adirondacks? Probably not, but if you did, you might easily mistake it for just another vole. But rest assured, they are out there, doing their part to keep the greenery cut back and the bellies of predators full. Life is good.

Photo copyrighted by and used with permission from Phil Myers, Museum of Zoology, University of Michigan.

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Ellen Rathbone is by her own admission a "certified nature nut." She began contributing to the Adirondack Almanack while living in Newcomb, when she was an environmental educator for the Adirondack Park Agency's Visitor Interpretive Centers for nearly ten years.

Ellen graduated from SUNY ESF in 1988 with a BS in forestry and biology and has worked as a naturalist in New York, New Jersey, and Vermont.

In 2010 her work took her to Michigan, where she currently resides and serves as Education Director of the Dahlem Conservancy just outside Jackson, Michigan.

She also writes her own blog about her Michigan adventures.





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