How Far South did the Wolverine (Gulo gulo) Range during Ice Ages?

The voracious wolverine preys upon deer, caribou, and even moose when these much larger mammals flounder in deep snow.  The padded paws of the wolverine allow them to stay on top of the snow while the heavy hooved deer sink, making it easy for the wolverine to lock their jaws on a throat. The wolverine also preys on smaller animals and will eat insects and berries.  They live in remote wilderness areas, preferring high elevations with deep snow and plenty of tree or shrub cover.   Wolverines benefit from the presence of other large predators because they are just as much scavenger as predator.  During summer and fall wolverines are too clumsy to actively chase deer but will drive off much larger predators from their kills.  After they consume as much as they can eat, they spray musk on the remains, and it become unpalatable for other carnivores.  Wolverines store caches of dead meat during winter and are ideally suited to survive in cold unproductive natural communities.

Image result for historical range of wolverine

Historical range of the wolverine.  Camera traps suggest they have recently recolonized northern California. They also live in Eurasia.  During Ice Ages, wolverines probably ranged along the southern Appalachians perhaps as far south as north Georgia and Alabama.

Image result for Gulo gulo

Male wolverines reach weights of 60 lbs but can drive away bears, cougars, and wolf packs. Wolverine cubs sometimes fall victim to the latter 2.

Wolverines occupy very large territories.  Males in Montana patrol 162 square miles on average, while male Yellowstone wolverines average a territory of an astounding 307 square miles.  Wolverines  live in low densities in boreal forests, and this makes their remains rare in the fossil record.  Nevertheless, subfossil remains of wolverines, dating to the Pleistocene, have been excavated from Maryland, Pennsylvania, Wyoming, Colorado, Nevada, Romania, Italy, Germany, France, and the United Kingdom.  (The wolverine is an Holarctic animal, living on both sides of the Arctic Circle.)  The specimen from Cumberland, Cave, Maryland is the southernmost known record of the wolverine in eastern North America and this is south of their known historical range during colonial times.  I hypothesize wolverines ranged into the southern Appalachians as far south as north Alabama and north Georgia during Ice Ages.  The key is deep snow–any climatic phase when deep snow regularly occurred at high elevations in the southern Appalachians would have been an invitation for wolverine range expansion south.  Other boreal species of mammals are found in the fossil record this far south including caribou, fisher, pine marten, porcupine, bog lemming, and red-backed vole.  Wolverine skeletal evidence is probably absent because they lived in low population densities at high elevations in forested environments where fossil preservation is rare.  Historical wolverine range is closely correlated with regions where snow stays on the ground through a good portion of spring.  Undoubtedly, spring snow cover existed in the southern Appalachians during the coldest stages of Ice Ages.

Most of the wolverine’s present day range was covered by glacial ice during Ice Ages, so it seems likely their range shifted south, like that of so many other species then.  How far south did this range shift?  We can only speculate.  But this is an animal that requires deep wilderness, and North America was nothing but deep wilderness before man.  Wolverines won’t cross clear-cuts or burned over land.  The main factor restricting wolverine range before man were the extensive grasslands that likely formed an ecological barrier to their expansion below the southern Appalachians.

References:

Hornocker, M; and H. Hash

“Ecology of the Wolverine in Northwestern Montana”

Canadian Journal of Zoology 59 (7) 1981

Inman, R.

“Wolverine Ecology and Conservation in the Western U.S.”

Swedish University Doctoral Thesis 2013

http://www.paleobiologydatabase.com

 

 

Advertisement

Tags: , , ,

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s


%d bloggers like this: