1975 – Grizzly bears in the lower 48 conterminous states were placed on the endangered species list as a threatened species.
March 29, 2007 – Despite the concurrent declines of several different grizzly foods, habitat loss, and genetic problems, the U.S. Fish and Wildlife Service removed Yellowstone-area grizzlies from the protected list of threatened and endangered species. The Center had submitted comments urging the Service not to remove these bears from the threatened species list, outlining their still-precarious situation — but to no avail.
June 4, 2007 –The Center joined six other conservation groups in filing suit to restore threatened status to the Yellowstone grizzlies. The Center also submitted comments requesting that the Fish and Wildlife Service revise its 1993 grizzly bear recovery plan, identify new recovery areas, designate critical habitat, and uplist the entire species from threatened to endangered. Other conservation organizations filed another lawsuit challenging the delisting as well.
June 25, 2007 – The Center filed suit against illegal sheep grazing in the Yellowstone ecosystem that jeopardizes grizzly bears and other imperiled carnivores.
September 21, 2009 – The Montana District Court issued an order in favor of plaintiff conservation organizations, vacating the delisting rule.
March 26, 2010 – Per court order, the Fish and Wildlife Service reinstated federal protection for Yellowstone grizzlies.
April 6, 2010 – In response to a lawsuit and comments submitted by the Center for Biological Diversity and Western Watersheds Project, the U.S. Sheep Experiment Station in eastern Idaho, run by the U.S. Department of Agriculture, issued a decision to halt the grazing of sheep on about 7,500 acres of vital grizzly habitat in the greater Yellowstone ecosystem.
November 22, 2011 – After the Fish and Wildlife Service appealed the 2009 Montana District Court order, the Ninth Circuit found that the agency had failed to adequately analyze the impacts of climate change on whitebark pine, a major food source for Yellowstone grizzlies. As a result, Yellowstone grizzlies remained under federal protection.
June 20, 2013 – The Center and seven other conservation organizations submitted comments to the U.S. Fish and Wildlife Service arguing that a recently proposed recovery plan for Yellowstone grizzly bears puts the animals' population at greater risk of extinction by allowing the removal of protections despite lack of connectivity with other populations and ongoing threats to the bears.
November 7, 2013 – Brushing aside mounting evidence that Yellowstone's grizzly bears face increased threats from genetic isolation, loss of key foods, and increased human conflicts and mortalities, federal and state officials are recommending removal of Endangered Species Act protections for the bears as early as the following year.
December 11, 2013 – Ignoring mounting evidence that Yellowstone's grizzly bears face increased threats from loss of key foods and human-caused deaths, federal and state officials unanimously recommended that Endangered Species Act protections be stripped from the region's iconic bears. The Center filed a request under the Freedom of Information Act for all documents and interagency correspondence used in developing the study behind the delisting.
December 19, 2013 – Citing concerns that federal estimates of Yellowstone grizzly bear population size and trends are not reliable, the Center for Biological Diversity, Sierra Club and Natural Resources Defense Council sent a letter to the Fish and Wildlife Service asking it to release all the data on which those estimates are based.
June 18, 2014 – The Center filed a legal petition calling on the Service to greatly expand its plans for recovering grizzly bears, including returning the iconic animals to vast portions of the American West.
December 18, 2014 – The Center for Biological Diversity filed a petition requesting that the Service develop a new rule to reintroduce grizzly bears to the Selway-Bitterroot ecosystem in central Idaho and western Montana.
August 12, 2016 – The Center and allies filed a lawsuit challenging the Montana Fish and Wildlife Commission's illegal, fast-tracked adoption of grizzly bear hunting regulations opening the door for trophy hunting following the bears' loss of Endangered Species Act protections (with a final rule removing Yellowstone grizzly bears from the endangered species list expected as early as November).
January 12, 2017 – The National Park Service and Fish and Wildlife Service announced their consideration of an attempt to increase the population of grizzly bears in the North Cascades by moving bears from other populations. At the time of the announcement, grizzly bear numbers in the North Cascades were dismal, with the Service estimating that fewer than 10 grizzly bears had occupied the area in 2016.
June 30, 2017 — A coalition of tribal and conservation interests, including the Center, announced its intention to sue the U.S. Fish and Wildlife Service over the agency's decision to remove federal protections for grizzly bears in the Yellowstone region.