What was the Pleistocene Range of the Canadian Lynx (Lynx canadensis)?

William Brewster was an ornithologist who went on an expedition to the North Carolina mountains in 1885 before much of it was logged.  He was interested in finding boreal species of birds in the higher elevations where spruce forests replaced deciduous forests.  On Whiteside Mountain he found a remarkable forest of 70 foot tall hemlock trees with a thick understory of 25 foot tall rhododendrons.  The highlight of his expedition though was his journey to the summit of Black Mountain.  Below 4050 feet, a forest of oak, hickory, chestnut, tulip, beech, and sugar maple covered the mountain.  Brewster declared it the finest forest he had ever seen–many of the trees were 6-7 feet in diameter, 125 feet tall, and neatly spaced 100 feet apart.  At 4050 feet, Brewster encountered the first red spruce tree.  A mixed forest of red spruce and deciduous trees stood between 4050 and 5050 feet.  At this elevation he encountered red squirrels–an animal that prefers boreal forests, but he had begun seeing boreal species of birds at 3600 feet..  Above 5050 feet, the forest consisted of red spruce, balsam fir, and a few yellow birches.  Stunted black spruce trees grew at the summit.  Brewster camped near the summit and heard a wolf howl and saw sign of bear and deer.  Evidentally, large mammals hadn’t been extirpated from this region yet.  He also mentioned in his journal that locals believed Canadian lynx lived at higher elevations, replacing bobcats which roamed the lower elevations.  Other than this passage, I can find no evidence in the scientific literature of Canadian lynx in North Carolina.

Historical range map of the Canadian lynx.  There’s no concrete evidence they lived farther south than this within historical times. However, 90% of their historical range was under glacial ice during the height of the last Ice Age.  They must have occurred farther south then.

Canadian lynx.  Note the big paws and long legs that help them run through snow.  This gives them a competitive advantage over their close relative–the bobcat–in regions with heavy snowfall.  Bobcats outcompete lynx everywhere else.

The Canadian lynx is well adapted to living in deep snow.  They have wider paws and longer legs than those of bobcats, and this gives them an advantage over their close relatives when running through soft snow.  Historical records show Canadian lynx were plentiful in mountainous regions of New York and Pennsylvania, and a few even lived in West Virginia.    There are no records of Canadian lynx in Virginia, North Carolina, or Tennessee where potential habitat at higher elevations existed.  It’s likely deep snows didn’t occur often enough to give Canadian lynx a competitive advantage over bobcats here.  Overall, bobcats (Lynx rufus) are a more adaptable cat species.  I believe the locals Brewster mentioned were mistaken.  However, it is probable that Canadian lynx ranged farther south during the height of the Ice Age when over 90% of their current range was covered by glacial ice, making all of Canada unsuitable for most organisms.

Canadian lynx prefer habitat favorable to the main item in their diet–snowshoe hares (Lepus americanus).  Snowshoe hares make up 75% of the Canadian lynx’s diet.  Snowshoe hares are most abundant in disturbed spruce/fir or spruce/northern hardwood forests.  They thrive in the brushy second growth that covers clear cut tracts in the decade following logging.  This kind of habitat also occurs naturally when blizzards blow down large stretches of spruce/fir forests.  Like Canadian lynx, snowshoe hares are well adapted to living in regions with deep snow, but lose their competitive edge to similar species in areas with a more moderate climate.  Cottontails breed faster and are more adaptable than snowshoe hares.  Historically, snowshoe hares did live farther south than Canadian lynx, occupying the higher elevations in the mountains of Virginia, North Carolina, and Tennessee.  They still live in West Virginia.  But I think bobcats, not Canadian lynx, were their main feline enemies in the more southerly parts of their range.

The snowshoe hare turns brown during summer to blend in with the forest floor and white during winter to blend in with the snow.  They are part brown and part white in fall and spring.  They are also known as varying hares because their coat color varies with the seasons.

Historical range map of the snowshoe hare.  I believe it has been extirpated from North Carolina, Tennessee, and Virginia.

When Canada was underneath the Laurentide Glacier some 20,000 years ago, the Canadian lynx must have ranged farther south than it does today.  Paleobotanical evidence does show that boreal forests, their required habitat, predominated as far south as the north Georgia mountains when cooler climates and lower atmospheric CO2 levels allowed spruce trees to grow at lower elevations.  Deeper snows likely occurred more often in these southerly latitudes then.  Unfortunately, Pleistocene-aged fossils of Canadian lynx are scarce throughout the whole continent and completely absent in the south, unlike bobcat fossils which are among the most common mammals found in fossil sites all over North America.  Some of the fossils of Canadian lynx that have been found date to the Sangamonian Interglacial over 118,000 years ago, indicating it is not a recently evolved species, so it must have been present somewhere south of the ice sheet.  It may be possible to predict the Ice Age distribution of Canadian lynx by using snowshoe hare fossils as a proxy.  Snowshoe hare fossils have been found in Arkansas and Missouri–well south of their present day range.  The presence of snowshoe hares makes it likely Canadian lynx were in the environment preying upon them this far south as well. Fossils of carnivores are usually less common than fossils of herbivores because they are less abundant than their food source.  This explains the absence of Canadian lynx fossils  in areas where they may have lived in the past.  Although fossil evidence in Georgia is lacking, Arkansas is close in latitude to north Georgia.  I assume Canadian lynx and snowshoe hares occupied the higher elevations of north Georgia during snowy climate phases of the Last Glacial Maximum.

On the fringes of their ranges, Canadian lynx and bobcats occasionally interbreed.  In all recorded cases of interbreeding, it was a male bobcat that mated with a female Canadian lynx.  Bobcats are much fiercer than their northern cousins, and a male tom bobcat will always drive off male lynx.  From what I’ve read, it’s not clear whether bobcat/Canadian lynx offspring are fertile.  Attempts by fur farmers to backcross bobcat/lynx hybrids have failed.

Tags: Black Mountain North Carolina, bobcat, bobcat/Canadian lynx hybrid, Canadian lynx, Ice Age range of Canadian lynx, Lynx canadensis, lynx rufus, Snowshoe hare, Using snowshoe hare fossils as a proxy for the presence of Canadian lynx, Whiteside Moutain North Carolina, William Brewter