Answer:
Environmental changes
The European presence in America spurred countless changes in the environment, negatively affecting native animals as well as people. The popularity of beaver-trimmed hats in Europe, coupled with Native Americans’ desire for European weapons, led to the overhunting of beavers in the Northeast. Soon, beavers were extinct in New England, New York, and other areas. With their loss came the loss of beaver ponds, which had served as habitats for fish as well as water sources for deer, moose, and other animals. Furthermore, Europeans introduced pigs, which they allowed to forage in forests and other wildlands. Pigs consumed the foods on which deer and other indigenous species depended, resulting in scarcity of the game native peoples had traditionally hunted.
European ideas about owning land as private property clashed with indigenous people's understanding of land use. Native Americans did not believe in private ownership of land; instead, they viewed land as a resource to be held in common for the benefit of the group. Colonizers erected fields, fences, and other means of demarcating private property. Indigenous people who moved seasonally to take advantage of natural resources now found areas off-limits, claimed by colonizers.
Introduction of disease
Perhaps the single greatest impact of European colonization on the North American environment was the introduction of disease. Microbes to which native inhabitants had no immunity caused sickness and death everywhere Europeans settled. Along the New England coast between 1616 and 1618, epidemics claimed the lives of 75 percent of the indigenous people. In the 1630s, half of the Huron and Iroquois people living near the Great Lakes died of smallpox. The very young and the very old were the most vulnerable and had the highest mortality rates. The loss of the older generation meant the loss of knowledge and tradition, while the deaths of children only compounded the trauma.
Some indigenous people perceived disease as a weapon used by hostile spiritual forces, and they went to war to exorcise the disease from their midst. These “mourning wars” in eastern North America were designed to gain captives who would either be adopted or ritually tortured and executed to assuage the anger and grief caused by loss.