Voles are among the most abun­dant mam­mals in North Amer­i­ca, but most peo­ple have nev­er actu­al­ly seen one. There’s a native vole species found pret­ty much any­where from the Arc­tic into Mex­i­co. There are a cou­ple dozen species in North Amer­i­ca, and about twice as many in the Old World. 

These fuzzy beasts are one species I study (this Mead­ow Vole, Micro­tus penn­syl­van­i­cus, was at a rest stop in Mass­a­chu­setts), and I whole­heart­ed­ly agree with the sen­ti­ment expressed in by the author of a recent review of vole genet­ics:

“Nobody has posters of voles on their wall,” said J. Andrew DeWoody, asso­ciate pro­fes­sor of genet­ics in the Depart­ment of Forestry and Nat­ur­al Resources, whose study appears this month in the jour­nal Genet­i­ca. “But when it comes down to it, voles deserve more attention.”

The paper dis­cuss­es the often bizarre genet­ic and chro­mo­so­mal diver­si­ty of voles. For most ani­mals, dif­fer­ences in chro­mo­some num­ber is enough to make a new species, if not a new genus. Vari­abil­i­ty in chro­mo­some num­ber is appar­ent­ly quite com­mon in voles, some­times with­in a sin­gle species. 

Oth­er researchers are inter­est­ed in voles because of their range of behav­ioral sys­tems. Some voles are monog­a­mous, oth­ers are polyg­a­mous, while oth­ers vary their mat­ing sys­tem depend­ing on cli­mate. Under­stand­ing the genet­ic dif­fer­ences and hor­mon­al respons­es asso­ci­at­ed with that vari­a­tion gives insight into sex­u­al behav­ior in humans and oth­er species. 

My inter­est in voles has noth­ing to do with chro­mo­somes or hor­mones. The abun­dance of voles makes them excel­lent test sub­jects for attempts to mod­el species dis­tri­b­u­tions. Where they occur is well known, and many of the envi­ron­men­tal fac­tors that lim­it their range is under­stood as well. There’s even a good lit­er­a­ture on inter­ac­tions between dif­fer­ent species of voles.

Poke around in a field near you and you might find the run­ways that they build, a sys­tem of cleared trails that they run through, feed­ing on grass and oth­er leafs. Fol­low a run­way back and you may find the den where pups are born.

A vole is basi­cal­ly a breed­ing machine. A female becomes repro­duc­tive at a few weeks old, and can pro­duce a lit­ter of 3–4 pups every few weeks from then on. If not for intense pre­da­tion, voles would eas­i­ly take over the world.

Luck­i­ly for us, voles remain hid­den, kept in bay by fox­es, hawks, snakes, weasels, and a host more eas­i­ly seen animals.