Flight: Canyon VEC to Hayden - “Start”
Let’s start our journey with a virtual flight from the Canyon Visitor Education Center to the Hayden Valley. The Hayden Valley is located 6 miles to the South of the Canyon Visitor Education Center and is often referred to as the heart of the park. The time of year is late summer, July through October, when the Central Bison Herd is congregating in high numbers for the annual rut, (the breeding season).
Flight: Hayden to Firehole - “Where do bison go in early Winter?”
As the first snows fall, the bison start their winter migration to escape the deep snow to come. The best way out of the Hayden Valley high country is to the west, toward the Firehole Valley. Their migration follows a series of geothermal areas that guide them through the forests that separate the Hayden Valley from the Firehole Valley. Once through this forested area, the route to the west offers bison an easy walk down hill along Nez Perez Creek, where they eventually reach the Firehole Valley, home of Old Faithful. As many as 1,100 bison can occupy the Firehole Valley during winter..
Flight: Firehole to West Boundary – “Where do bison go in late Winter?”
As the snows of winter continue to accumulate, foraging becomes more difficult. Consequently, bison have to decide whether they will stay put or travel to lower elevations where shallower snow makes searching for food easier. Many of the bison take a route north along the Firehole River, to Madison Junction, and then west down through Madison Canyon. <pause> Eventually, they approach the western boundary of the Park. At these low elevations, the snow melts early. [But] If the bison migrate far enough west they leave the protection of the National Park.
Flight: West Boundary to Firehole – “Where do bison go in Spring?”
Just as the snow can push the bison out of the high country in the center of the Park, the spring can pull them back in from the Boundary. This is the start of the summer migration. The timing of this migration follows the receding snowpack, and the greening up of the landscape that the snows leave in their wake. Following the green-up takes the bison back up Madison Canyon, and on toward the Firehole Valley.
Flight: Firehole to Hayden Valley – “Where do bison go in Summer?”
As grasses mature, they become less nutritious to bison. So the bison continue to migrate even higher to where Spring is just beginning. This is the final leg of their migration.They follow Nez Perce Creek back upstream, over the forested Central Plateau, and into the high meadows of the Hayden Valley. The habitat is wide open, food and water are abundant and the long days of summer provide plenty of time to eat and replenish those lost fat reserves.
Scripts for stories at each stop
Story: The Rut – “What are bison doing in the Firehole Valley”
Every summer, all the bison of the central herd have followed a green wave of grass to heart of the Park, Hayden Valley. This is a time when the bison are replenishing their fat reserves and returning to their breeding areas. The breeding season is commonly referred to as the rut and occurs from mid July to about the end of August. A few percent of bison will breed outside this time period. During this time period adult male bison battle each other for the right to mate with the willing cows in the group. The bulls want to be the biggest-baddest bison around so that they can attract as many cows as they possibly can. To sire as many of the following years calf crop is the ultimate goal for these burly bulls.
Story: Winter Is Hard – “What are bison doing in Firehole Valley?”
Bison are naturally adapted to withstand fierce winter winds and cold temperatures. A combination of thick skin, a dense coat of hair, and a large body size to store fat reserves will usually insure the survival of healthy bison through the difficult late winter time period. Bison are able to smell and locate their winter food even if it lies under deep snow. Their massive heads and shoulders can then be used as "snow plows" to push aside the snow to expose any dried grasses and sedges, this is called cratering.
Story: Calving – “What are bison doing at the Park Border?”
Even though bison can withstand harsh winters, they generally spend the winter burning more calories than they consume. Diet quality declines after the plant growing season and the cumulative affects of feeding on a declining quality of food source results in a peak of mortality at the end of winter just prior to new flesh of green on the landscape. Predators are often more successful during the late winter when bison are tired and are moving slow.
Story: Summer migration - “What are bison doing in Firehole Valley?”
Adult female Bison, ages 4 to 12 are the most fecund. They typically give birth to one calf every spring. The calves are born orange in color and lack the distinctive hump on their backs. They will stand shortly after birth and soon will be running and playing with other calves. Calves will nurse for about 9 months, but they begin to eat grass during the first month.
(January 2007 - Contributors: Thor Anderson, Jon Detka, Rick Wallen, PJ White, Jordan Plotsky, Fred Watson, etc.)