Meadow Vole
Have you ever felt like life was causing you to just run around in circles? It seems that happens to all of us from time to time, but Ill bet none of you can mirror the experience of a Meadow Vole that Tom Shisler (site manager at Wahkeena Nature Preserve) and I watched this past November 12th.
Tom and I had stopped to talk near Wahkeena’s silt pond when we spotted a Meadow Vole (probably Microtus pennsylvanicus) running in circles on top of a thin skim of ice on the pond. The vole just kept circling and circling at a run, virtually non-stop for at least 20 minutes. Typically it ran in one to two foot diameter circles, but sometimes circles as small as 2 inches in diameter and once or twice in circles as much as 10 feet in diameter. The circles were always clockwise. A couple of times it stopped very briefly to groom — always grooming its right side, and often just falling over to its right side while grooming. As it ran, its circles gradually moved southwest to northeast across the surface of the thin ice. At one point, it came to a spot with no ice film, and it swam in circles here until it got back onto the ice. 
After 20 minutes it stopped briefly near shore, and I caught it with a gloved hand. Tom and I briefly examined the vole, and could see no obvious injury. Then I released it on dry land. The vole sat there for a minute or two — then eventually ran off (rather slowly and in fits and starts) into taller vegetation. Previous to capture, once it came with its circles to the edge of the pond, and even ran in clockwise circles up into the leaf litter, then back onto the pond. It did not by itself leave the pond any further, until I captured it five minutes later. Total observation time of this circular running was twenty minutes. Very strange behavior. I vaguely recall something about a parasite, but cannot recall any specifics. I know that trout have a whirling disease but few parasites would affect both fish and mammals. After a lot of web-searching, one of the websites I found wondered if it could be from the toxin of a bite from a Short-tailed Shrew (Blarina brevicauda). I sent a similar e-mail back in November to a wildlife disease site, but never got any answer from them. I also tried a couple of mammalogists I know and none of them had any clues nor any suggestions for other places to search for information.
So our circling Meadow Vole remains a mystery. Even without a specific answer, it was a fascinating observation. If any of our readers have any information on this phenomenon, or any sources where we might find an answer, please let us know!
Bob Glotzhober
Curator Emeritus, Natural History
