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Yosemite National Park Environmental Factors
Threats to park resources and the integrity of park ecosystems include loss of natural fire regimes, air pollutants and air-borne contaminants, global climate change, direct impacts to resources from high visitation in some areas of the park, habitat fragmentation from both outside and inside park boundaries, and the invasion of non-native plant and animal species. The park is actively attempting to control the non-native plant species that pose the most serious threat, such as spotted knapweed, yellow star-thistle, bull thistle, and Himalayan blackberry. The presence of wild turkeys, white-tailed ptarmigan, bullfrogs, introduced fish and other non-native animal species in Yosemite threaten the park's native species.
Maine ocean islands provide the only nesting sites for Atlantic puffins in the United States. Eastern Egg Rock in the midcoast region, Seal Island and Matinicus Rock at the mouth of Penobscot Bay, and Machias Seal Island and Petit Manan Island off the downeast coast provide habitat for more than 4,000 puffins each summer.