Lab 5: How Wolves Change Rivers (Due Monday, September 11th by 11:59 PM)
Watch the video (5) How Wolves Change Rivers - YouTube and then answer the following questions.
- What is a trophic cascade? (3 points)
A trophic cascade is an ecological process that starts at the top of the food chain and tumbles all the way down to the bottom. Effects ripple through multiple trophic (feeding) levels, ultimately influencing the structure and dynamics of the entire ecosystem.
- When were wolves reintroduced to Yellowstone National Park? (3 points)
1995
- How long had wolves been absent from Yellowstone National Park? (3 points)
70 years
- How did the absence of wolves in Yellowstone affect the ecology? (3 points)
The number of deer had significantly increased since there was nothing to hunt them. This led to the reduction of vegetation to almost nothing.
- How did the reintroduction of wolves change the behavior of the deer? (3 points)
The deer started avoiding parts of the park where they could be easily trapped, including valleys and gorges.
- What happened to the trees after the wolves were reintroduced? (3 points)
The height of the trees significantly increased. The number of trees also increased because Bear Valley sides quickly became forests of Aspen and Willow and cottonwood.
- Which animals increased in numbers or returned to the park after the wolves were reintroduced? Why did this happen? (3 points)
Songbirds and Migratory Birds. This was as a result of increased trees giving them a habitat. Beavers also increased to eat trees. In addition, the number of rabbits and mice began to rise since wolves killed coyotes, which meant more hawks, weasels, foxes, and badgers since rabbits were their food.
Ravens, bald eagles, and bears increased because they fed on carrion left by wolves.
- How did the wolves change the behavior of the rivers? (3 points)
They began to meander less; there was less erosion, the channels narrowed, more pools formed, and more riffle sections. This is because the regenerating forests stabilized the banks, so they collapsed less often and the rivers became more fixed in their course.
- As of December 2021, how many wolves were in Yellowstone National Park? https://www.nps.gov/yell/learn/nature/wolves.htm (3 points)
97
- Why had the numbers of wolves declined in Yellowstone and throughout the United States? Are the gray wolves currently protected under the Endangered Species Act? (3 points)
Wolf Restoration - Yellowstone National Park (U.S. National Park Service) (nps.gov)
The number of wolves had decreased because of the westward expansion, where native wolves’ bases were transformed into agricultural and settlement sites. As a result, wolves began to prey on domestic stock, and in return, humans eliminated wolves from most of their historical range. Predator control, including poisoning, was practiced in the park.
Gray Wolf Recovery News and Updates | U.S. Fish & Wildlife Service (fws.gov)
Since February 10 22, gray wolves in the contiguous 48 states and Mexico – with the exception of the Northern Rocky Mountain population – are now protected under the Endangered Species Act (ESA) through court ruling.