To most Americans, the Endangered Species Act of 1973 has been an astounding success, saving some 99 percent of listed plants and animals from extinction, including iconic birds like the Bald Eagle and Whooping Crane. But it’s far from an industry darling. Critics of the law argue that it puts an unnecessary burden on the land users that brush up against it. Their frustrations have, in turn, inspired a fresh wave of political efforts intended to make the law more maneuverable for businesses—a push conservationists fear will undermine the species it protects. According to the Center for Biological Diversity, since January of 2017 more than 75 bills and amendments have been introduced in Congress that would simplify, restrict, or outright weaken the act, ranging from attempts to delist individual species to defunding specific projects. “The vast majority of these proposals are basically lobbing bombs at the ESA,” says Ya-Wei Li, the director for biodiversity at the...