As of end of 2013, there are now at least 83 Mexican gray wolves living in the mountains along the Arizona-New Mexico border.

That's an increase of ten percent from 2012, and the endangered species' population has now doubled in the last four years.

An Interagency Field Team of the Arizona Game and Fish Department counted Mexican gray wolves at their recovery zones in the wild at the end of 2013, and said they spotted 83, though there is always the possibility of more.

All of the animals living in the recovery zone were born in the wild, not in captivity.

At least 37 wolves are living in Arizona, and no fewer than 46 are in New Mexico.

While recent years have shown significant growth, the number of Mexican gray wolves in the wild still falls far below expectations from when reintroductions started in 1998. The program anticipated there would be more than 100 wolves by 2006.

The gray wolf recovery team not offered any explanation as to why they have fallen short of the original goal.