Do you (like this reporter) think caribou are fascinating super-animals abound with tantalizing biological mysteries waiting to be unwrapped by the open and scientific mind?
Do you also (unlike this reporter) love to cross-country ski in the gorgeous, snow-lit backcountry?
Then you should definitely throw your ski boots on and head out to Lucky Lake in Watson Lake in March. Environment Yukon is hosting a“ski-bou” and government biologists will lead skiers out into caribou’s winter habitat in the hopes of finding signs of – or maybe even seeing – some ‘bou.
(This reporter, sadly, cannot go, as she is the worst cross-country skier ever born and does not need help falling on her face, thank you very much.)
Although we tend to think of the same animal when we think about caribou, the Yukon is actually home to three subspecies: northern mountain woodland caribou, barren-ground caribou and boreal caribou, says Environment Yukon ungulate biologist Kelsey Russell.
Perhaps the most famous – and lately, the most talked about, due to threats to its calving ground in the Arctic National Wildlife Refuge in Alaska – are barren-ground caribou (Rangifer tarandus groenlandicus), specifically the Porcupine caribou herd, says Russell. This subspecies is well-known for tremendously long – and “pretty unique” – migration routes, with the Porcupine herd making a yearly migration from Alaska into the Yukon and Northwest Territories and back again, says Russell.
By contrast, woodland caribou (Rangifer tarandus caribou) – which comprise “pretty much most of” the caribou in the Yukon, Russell notes – do not have such an extreme schedule to keep, and their migrations tend to be more altitudinal than longitudinal – a fancy way of saying they go up and down mountains instead of across huge swaths of tundra. Woodland caribou spend the fall and winter months in forested areas at low altitudes and spring and summer months at high elevations, which help protect them from predators and escape swarms of black flies and mosquitoes which teem through the boreal forest in the warmer months.
Likewise, the two subspecies have drastically different reproductive strategies. Barren-ground caribou time their calving all together, and gather in huge groups to raise their offspring. This provides barren-ground animals with a “strength-in-numbers” advantage, as predators tend to be deterred by large numbers of adults, says Russell, and are also territorial, meaning the caribou limit their overall exposure to predator – there are only so many baby caribou a handful of hungry polar bears can eat, for example. By contrast, woodland caribou employ the total opposite strategy, dispersing to give birth, similar to deer, and are “more cryptic” and harder to find during this time, Russell says.
Although all – including those living outside the Yukon — caribou subspecies occupy different ecological zones, their diet remains similar, Russell says, with lichen – that delightfully strange symbiont of algae (or cyanobacteria) living in a mutualist arrangement with fungi we often see every day without full appreciation of its complexity – making up 60 per cent of their diet, which is supplemented with fresh greens and shoots when available.
All caribou also “love mushrooms,” Russell says, and will eat them whenever they can find them.
Physically speaking, barren-ground caribou tend to be a bit lighter and smaller than their woodland cousins, says Russell. By contrast, woodland caribou in the north tend to be larger than woodland caribou in the south, which is in keeping with Bergmann’s Rule, which states that animals of the same species tend to be larger the farther north you go, because it is metabolically less expensive to heat a large body and keep it warm than it is to heat a small one (think about how hard it is for little dogs to keep warm in the winter versus large ones).
There are around 26 distinct mountain woodland caribou herds in the Yukon, says Russell. The Porcupine herd is the only true barren-ground herd in the Yukon, although it’s worth noting that herd is doing “very well” at the moment, numbering between 202,000 and 235,000 animals according to recent estimates.
There is also a small population of boreal caribou in the Peel watershed, an area recently in the news again due to the release of a public survey which shows heavy Yukoner support for protection in the region.
Boreal caribou behave a bit more like deer, says Russell, and don’t typically migrate much, preferring to “hang out in swampy, muskeg-y areas.”
While subspecies are genetically distinct from one another – in, say, a similar way to how a husky is genetically distinct from a malamute – it’s important to note they are still caribou and subspeciation is not an exact science.
The 40 Mile herd – which has historically been more of a Northwest Territories herd but has been traversing into the Yukon “more and more” — are actually a “mystery herd,” says Russell. Although they look like barren-ground ‘bou and share the same environment, they are more behaviourally and genetically similar to woodland caribou.
Overall, says Russell, most of the caribou populations in the Yukon are “pretty stable.”
“In general, they’re doing pretty well.”
People interested in ski-bouing on March 2 will (hopefully) encounter woodland caribou from the Little Rancheria or Horse Ranch herds, says Russell. Environment Yukon is hosting another ski-bou March 17 at the Mount Lorne Community Centre, during which participants will hopefully encounter caribou from the Carcross herd.
Participants are encouraged to dress appropriately for the weather and need to supply their own skis and equipment. Pets should not attend this event, as they might frighten sensitive wildlife, including caribou. Visit www.yukon.ca/events for more details.
Contact Lori Fox at firstname.lastname@example.org