Since passage of the Endangered Species Act 50 years ago, more than 1,700 plants, mammals, fish, insects and other species in the U.S. have been listed as threatened or endangered with extinction. Yet federal government data reveals striking disparities in how much money is allocated to save various biological kingdoms.

Of the roughly $1.2 billion a year spent on endangered and threatened species, about half goes toward recovery of just two types of fish: salmon and steelhead trout along the West Coast. Tens of millions of dollars go to other widely known animals including manatees, right whales, grizzly bears and spotted owls.

But the large sums directed toward a handful of species means others have gone neglected, in some cases for decades, as they teeter on potential extinction.