Yellowstone Wolves and trophic cascades

Why were wolves absent from Yellowstone from the 1920's to 1995?

• There was no prey available, so they starved.

• When all the elk died, the wolves moved to Canada.

• Humans hunted and killed all the wolves in Yellowstone and the surrounding area.

• The wolves migrated south to Texas for a warmer climate.

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Wolves and elk sometimes hunt together for the same prey.

• True

• False

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Why was the songbird population reduced by the presence of too many elk in Yellowstone?

• Elk ate young trees, so birds had fewer places to nest.

• Elk ate too many songbirds.

• Wolves at songbirds when no elk were available.

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Other species that feed from an elk killed by wolves include

• foxes, rabbits, and mice

• bears, foxes, and beavers

• bears, eagles, and coyotes

• beavers, rabbits, and mice

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The species that creates habitat for fish and amphibians by building dams in rivers is

• otters

• coyotes

• elk

• beavers

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A niche ________________.

• is the function that an organism performs in the food web of that community.

• includes everything else the organism does and needs in its environment.

• is specific to each individual animal and plant.

• All of the above.

How long were the wolves absent from Yellowstone National Park?

• 1 year

• 5 years

• 10 years

• 70 years

Explain why the population of elk built up.

• There were just a lot of them and so they reproduced quickly.

• There was lots of food for the elk in the park so they reproduced well.

• There was no natural predator to hunt them so they became over populated.

• No one is actually sure why this happened.

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What happened to the vegetation because of the elk population?

• The elk ate it all, They reduced the vegetation to almost nothing, or they devoured it, leaving it bare.

• Nothing at all. the vegetation just grew as normal.

• A drought actually caused the vegetation to die and the elk trampled what was left.

• The elk ate some of it but lots of the vegetation remained.

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Why did the height of trees grow dramatically?

• The weather had been much better and the trees grew taller.

• The trees did not grow dramatically. Everything stayed the same.

• The elk was not there to eat it, and now it can grow.

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