What environmental damage existed in the americas before the arrival of columbus?

The European settlement caused many environmental problems that destroyed the natural habitat and affected the Native Americans. The people hunted beavers to a point of extinction to make European hats. The absence of beavers meant the loss of beaver ponds which were the water source for moose, deer and other animals. In addition, the fishes which relied on the pond as a habitat also got affected.  

Europeans also introduced pigs which grazed with animal hunted by the natives and this reduced the hunting territories since the pigs were not hunted. Another problem brought by Europeans was their belief in private ownership of land while the natives believed land should be shared and benefit everyone. Europeans barricaded their property with fences and walls making it hard for natives to get food and resources.

american troops were forced to withdraw following deadly bombings.

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