United States Fish and Wildlife Service (FWS) officials have reviewed recent evidence and say that the tortoise is not presently at risk and won't receive Endangered Species Act (ESA) protection.

FWS research suggests that, at present, 470,000 to 970,000 adult tortoises currently live in the Sonoran Desert. The agency stated that the numbers are due in part to ongoing and longterm efforts by the US and Mexican governments and the state of Arizona.

The finding is due in part to longterm commitments to continued proactive efforts between federal agencies and Arizona Game and Fish Department, in identifying and addressing the primary threats to the tortoise. The Service utilized a robust scientific analysis of the desert tortoise status and current and future threats and concluded it does not face extinction now or in the foreseeable future.

"This is yet another example of the power of the ESA in inspiring successful collaborations between states, landowners and federal agencies on behalf of America's most imperiled wildlife. When you combine this with other recent efforts culminating in not-warranted findings, such as the New England cottontail, greater sage-grouse and others, it is clear that the ESA is accomplishing its intended purpose in a flexible and collaborative way," said FWS director Dan Ashe in a statement.

The tortoise originally became a candidate for protection in 2010. At that time, FWS officials found that the animal's habitat was under threat due to increasing human populations in the region. However, ongoing efforts since that time and a classification by the state as a "species of greatest conservation need" have kept the population stable.

According to the Associated Press some environmental groups remain concerned about the ruling. Tylor Jones of WildEarth Guardians said that the group wants to see the animals reliably protected. Jones is not convinced however that voluntary agreements will be enforceable. She added that her group is reviewing the FWS report but has not ruled out legal action at this time.

"We and our federal and state partners will continue to monitor the tortoises. However the current modeling in science demonstrates that there's virtually no probability of extinction over the next decade," said FWS spokesperson Jeff Humphrey.

According to the report, the current evaluation of the tortoise's numbers included input from public and private sector experts as well as "geospatial and population viability" computer modelling.