More than 764,000 acres of land in southern Arizona and New Mexico has been federally designated as critical habitat for jaguars, which are endangered and rarely seen in the US.

The US Fish and Wildlife Service announced Tuesday that it was using the Endangered Species Act to protect 1,194 square miles (764,207 acres) of jaguar habitat. There is currently only one known jaguar living in the US, and it has been documented within this protected area.

A larger population of jaguars exists in Mexico, and the establishment of protected habitat in the US ensures that any of the cats that cross the border will not be forced out by human activity.

"I'm hopeful that decades from now we'll look back on this historic decision and see it as the first on-the-ground action that eventually led to the return of a thriving population of these beautiful big cats to this country," said Michael Robinson of the Tuscon-based Center for Biological Diversity, a non-profit conservation group that filed the lawsuit that led to the establishment of the critical habitat.

The protected land included six areas, each of which contain one or more mountain ranges where jaguars have been documented in the past.

Robinson said the critical habitat - which includes the Baboquivari, Pajarito, Atascosa, Tumacacori, Patagonia, Santa Rita and Huachuca mountain ranges in Arizona, the Peloncillo Mountains straddling the Arizona/New Mexico border, and the northern tip of the San Luis Mountains in New Mexico - is does not protect two key areas that were historically occupied by jaguars.

"While we're disappointed that the protection omits the best US habitat for jaguars - the rugged Gila headwaters in New Mexico and the pine-clad Mogollon Rim in Arizona - this decision is a milestone that protects much of the borderlands that the first generation of returning jaguars is exploring and inhabiting," Robinson said.

In establishing the critical habitat, the USFWS made a concession to Rosemont Copper, which intends to build a $1.23 billion copper mine in an area where the only known US jaguar has been seen. Photographs of the cat indicate that it makes its home near the site of the proposed mine. A 3,513 acre will be placed around the proposed mine site, according to the Arizona Daily Star.

Despite being located in the middle of the jaguar habitat, the mine was allowed by the USFWS because it takes up less than 1 percent of the jaguar's total critical habitat, the Daily Star reported.