There are now fewer Mexican gray wolves roaming the American Southwest, and federal officials say the numbers show more work needs to be done to restore the endangered species.
The annual survey released Thursday by the U.S. Fish and Wildlife Service shows at least 97 wolves are spread between southwestern New Mexico and southeast Arizona.
Federal officials say the numbers are disconcerting since the population had been on the upswing since 2010, with 2014 marking a banner year when the predators topped 110.
Biologists aren't certain whether the abrupt decline in 2015 was an anomaly. They're considering a number of factors, including the deaths of 13 wolves and a significantly lower pup survival rate.
The survey showed 23 wild-born pups survived in 2015 compared to 38 the previous year.
