Glacier National Park hosts a plethora of plants and animals; lots of usual suspects, such as bears, wolves, elk, and bighorn sheep, but also quite a few unique species. Most interesting among them are species of the North Fork, including incredibly tiny animals, some weighing even less than an ounce, and creative carnivorous plants. And with North Fork’s plentiful and varied bird species, birders will have a ball here.
The North Fork Valley is home to the rare northern bog lemming, a small, brown-backed, gray-bellied rodent that seeks mats of thick wet sphagnum moss for habitat. Weighing only one ounce (the same as one heaping tablespoon of sugar) but growing up to six inches long, the tiny cousin of the Arctic lemming is a relic of the Pleistocene ice age, which began two million years ago. Although it’s rarely seen, look for the small, neat piles of clipped grass it leaves along the mossy thoroughfares en route to underground nests. One study found that bog lemmings make up 2 percent of the pine marten’s diet.
Glacier’s smallest predator, the pygmy shrew, inhabits floodplains in the North Fork Valley.Glacier’s smallest predator, the pygmy shrew, inhabits floodplains in the North Fork Valley. This tiny carnivore is one of North America’s rarest mammals. Shorter than 2.5 inches in length and weighing less than a quarter ounce, this shrew’s voracious appetite for insects, slugs, snails, and carrion puts larger shrews to shame. One study watched a female eat three times her own body weight daily for 10 days. Their high metabolism echoes their respiration rate—25 times more frequent than humans—and their hearts beat up to 1,320 times per minute when excited. To feed their high metabolic rates, pygmy shrews eat every couple of hours 24-7 year-round.
Carnivorous plants inhabit North Fork fens. The sundew attracts insects to its sparkling droplets, which look like morning dew. Sitting atop hairs lining its leaves, the sticky droplets, like wet cement, trap unsuspecting visitors. Slowly, the leaves curl around the victim as digestive juices work their magic. The bladderwort has also refined trapping. Buoyant bladders trap anything that swims by—from mosquito larvae to fish fry. When the prey passes, it brushes hairs that open a trapdoor that sucks water in along with the naive prey. Digestive enzymes make short work of the meal, with the trap reset in 15 minutes to two hours.
Birders find a feast for the eyes and ears in the North Fork. With 196 species of birds documented—at least 112 nesters—the valley teems with avian activity. Migratory birds stop on their flight highways to wintering ranges or summer nesting. To help with identification of Glacier’s birds, pick up a bird list from visitors centers or on the park’s website.
Raptors: Birds of prey find abundant food in the North Fork Valley. Numerous rodents, ground squirrels, songbirds, and carrion feed their appetites. The valley’s forests attract sharp-shinned and Cooper’s hawks. Bald eagles nest on Kintla and Bowman Lakes. Northern harriers, red-tailed hawks, goshawks, and American kestrels prowl above the prairies. At night, the hoots of large great-horned and pygmy owls haunt the air.
Waterfowl: With the Flathead River, many large lakes, swamps, and wetlands, waterfowl have no shortage of suitable habitat. Herons, ducks, grebes, geese, loons, and swans migrate through or nest in the plentiful waters.
Songbirds: The North Fork could be considered downright noisy at times—not from auto traffic, but from the scads of songbirds flitting among its trees and cattails. American redstarts, warbling vireos, kinglets, nuthatches, crossbills, sparrows, and warblers are just a few of the neotropical songbirds that migrate annually into the valley. In winter, you’ll spot tree sparrows and redpolls.
Woodpeckers: After fires, dead standing timber attracts the three-toed woodpecker, picking away for bugs. Watch also for the large red-headed pileated woodpecker looking for a favorite food—carpenter ants.
Excerpted from the Fifth Edition of Moon Glacier National Park.