National Wildlife Federation

America harbors a remarkable array of plant and animal species, ranging from majestic mammals like bison and grizzly bears to tiny desert wildflowers.

Unfortunately, many of our species have not fared well over the past few decades suffering from things such as habitat loss and the spread of invasive species.

Scientists estimate that up to one-third of U.S. species are at increased risk of extinction, and more than 1,300 U.S. plants and animals already have been federally listed as threatened or endangered and protected under the Endangered Species Act.

National Wildlife Federation has long has been focused on protecting the most vulnerable of our wild species. 

From http://www.nwf.org/what-we-do/protect-wildlife/endangered-species.aspx