In America's youth, the most numerous bird on Earth was very likely North America's passenger pigeon. Today, incredibly, all are gone: the passenger pigeon was hunted to extinction by 1914.

Our landscapes still hold wildlife from lumbering grizzlies to tiny gnatcatchers, gray whales to gray wolves. But these animals are among many threatened by pressures such as pollution, habitat loss, invasive species and global warming.

Our nation's irreplaceable natural heritage should not be further diminished. What will our children and grandchildren think of us, should we fail to tend to this sacred trust?