We just returned from vacation to Big Sky Montana where we skied, mushed, tubed and rode in a sleigh. In addition, we visited Yellowstone National Park. We entered the park on a snowcoach tour and immediately stopped to observe some bison and trumpeter swans. We saw bison, elk, big horn sheep, a moose, dippers, trumpeter swans, a great blue heron, and bald eagles. We searched high and low for a river otter and coyote, but never spotted either.
Bison are the largest mammals in Yellowstone National Park. They are vegetarians. The males, called bulls, can weigh up to 1,800 pounds. Females (cows) weigh about 1,000 pounds.
Elk also live in Yellowstone. Actually, about 22,000 live there in the winter. Elk are the second largest member of the deer family (moose are larger). Adult bulls, weigh about 700 pounds while cows weigh about 500. Their coats are reddish brown. They have a yellow patch on their bottoms. Bulls grow antlers every year and their "rack" may weigh more than 30 pounds.
While we did not see a big horn sheep in Yellowstone, we did see one outside the park. Bighorn sheep are named for their large, curved horns. Females, or ewes, have horns but they are short and not as curved as the male horns. Sheep range in color from light brown to chocolate brown and they have a white rump and lining on the back of all four legs. Females weigh up to 200 pounds, and males occasionally exceed 300 pounds. The live primarily on rocky cliffs where they can hide from predators like coyotes. They eat grasses and plants and like to find natural salt licks. For this reason, they can sometimes be seen by the roads in Montana where salt has been used to keep winter roads clear.
The last animal we saw was a moose. Moose are rare in Yellowstone, but they can be found in the willows in the areas surrounding the park. They hang out there to gather food. We saw two moose in the area surrounding Big Sky. The wildlife viewing in Yellowstone was great and very different from anything we had seen before. Maybe one day we'll go back and go on a wolf watching tour!
During our park tour, we also observed many of Yellowstone's geologic features. We saw fumaroles, hot springs,mud pots, and geysers. We learned a lot about the geology of Yellowstone. The national park sits on a caldera and it is host to over 2/3 of the world's geysers. There are more than 10,000 thermal features there. We learned that the best way to spot eagles was to look in trees near the river. On our way to Old Faithful, we learned that the hills around Old Faithful and the Upper Geyser Basin are reminders of lava flows. These flows occurred after the eruption 600,000 years ago and flowed across the area. Glacier deposits underlie the geyser basins providing storage areas for the water used in eruptions. In the high mountains surrounding Yellowstone, water falls as snow or rain and slowly percolates through layers of porous rock. It sinks to about 10,000 feet and then the cold water comes into contact with the hot rocks in the magma chamber beneath the surface. As the water is heated, its temperature rises well above the boiling point to become superheated. The highly energized water is less dense than the colder, heavier water sinking around it. This creates convection currents that allow the more buoyant water to travel to the surface. As the water rises to the surface, the pressure drops and the heat energy creates a hot spring.
Fumaroles are hot springs where the water all boils away before reaching the surface. Where hot water is limited and hydrogen sulfide gas is present, sulfuric acid is generated and it dissolves rock into silica and clay. This dirt mixture mixes with water and forms the bubbling mudpots that are in Yellowstone.
The most unusual feature of Yellowstone is the geysers. In geysers, expanding steam bubbles build up beneath the ground and finally squeeze through the narrow passageways and force the water above to overflow from the geyser. When the water is released at the surface, there is a sudden decline in pressure of the hotter waters at great depth which causes steam explosions in which the volume of boiling water expands 1,500 times or more. This boiling superheated water bursts into the sky as a geyser. It is spectacular. If you haven't been to Yellowstone, put it on your list of places to see!