If you are lucky enough to see a wolverine, at first glance you might think you are staring at a mini-bear.  It’s not a bear and it is not related to a wolf.  A wolverine is the largest land-dwelling member of the weasel family.  Wolverines remain a mysterious creature that is hard to locate in the wild and even harder to study.

what is a wolverine

Wolverines live primarily in the arctic and alpine regions of Canada and Alaska.  Within the lower 48 states, wolverines inhabit the northern Rocky Mountains within Idaho, Montana and Wyoming.  They occupy the Northern Cascades of Washington and have been recently sighted in the Sierra Nevada range of California.  A wolverine’s territory is enormous, especially relative to its size.  Adult males weigh in at 24 – 40 pounds with a large male being 3.5 feet long (including its bushy tail).  Males' territories are estimated to be as large as 500 square miles.  They  have been tracked traveling over 25 miles in a day.  Wolverines traverse long distances over the roughest terrain.   Mountains, glaciers, snow, dirt and rock do not concern the wolverine or slow it down.  It's unhesitant desire to scale steep mountains, covered with deep snow in the most remote regions of the alpines, add to the lore of elusiveness and mystery.  At full speed, it leaps with both hind legs to both front legs achieving speeds of 4 mph.  A wolverine’s large territory is believed to be a direct result of the weasel looking for food.  A male’s vast territory is often shared with 1-4 females.  Females' territories are smaller than males and can encompass about 150 square miles.

Wolverines are lifetime polygamists.  A male will mate with several females.  Females raise the babies, called kits.  A female’s gestation period is 30-40 days and will give birth to 1-4 kits per litter.  A female will give birth once a year if there is an ample food supply.  Females give birth in dens about 8 feet deepwolverine den in snow which the mother builds to provide protection from predation and warmth.  Male wolverines have been observed to visit each of its families for a period of time while the kits are young.  Observations of family interactions include males spending time with kits for the first few weeks of life.  Some kits will travel with the father for a brief duration before going out on its own.

Scientist estimate a population of 300 wolverines within the lower 48 states.  Wildlife activists petitioned the United States Fish & Wildlife Service (USFWS) to list wolverines under the Endangered Species Act in 2000.  USFWS concluded it was not warranted.  Activists continued to pursue an endangered listing for wolverines.  Activists took the USFWS to court on two occasions; 2005 and 2008.  The lawsuit filed in 2008 petitioned the USFWS to consider the lower 48 state populations separately from the Alaska and Canada populations.  In 2010, the USFWS concluded that wolverines needed protections and were deemed candidate species for ESA protection.  Two considerations of note were included in the candidate selection for wolverines.  The first consideration was the result of the 2008 petition.  Wolverines on the waiting list for protection is only applicable to the distinct populations living in the lower 48 states.  A more robust population of 15,000 – 20,000 wolverines exist in Alaska and Canada.  The second consideration deals with climate change.  The USFWS considers the wolverine population of the lower 48 states to be endangered with the primary threat to survival being global warming.  Wolverines require cold temperatures, large territories, and deep snow for survival.  The occurrence of global warming is melting snow faster and raising temperatures thus limiting the environs that wolverines are so apt at surviving in. 

Wolverines placed on the candidate species listing provide no actual protections to the animal.  The label of candidate species means the specieswhat is a wolverine is on a waiting list to receive protections once higher priority animals are sufficiently protected.

Wolverines are one of the most unstudied and mysterious mammals in North America.  It would be a shame not to learn more about this versatile survivor before its habitat melts away and it becomes extinct.


Wolverine on the move in snowCredit: USFWS
Credit: USFWS