The number of endangered Mount Graham red squirrels in the Pinaleño Mountains near Safford has declined slightly according to a recent survey, state wildlife officials reported.

The survey — conducted jointly by the Arizona Game and Fish Department, Coronado National Forest, U.S. Fish and Wildlife Service and the University of Arizona — estimated 252 squirrels, said a news release from the Game and Fish Department. That’s a decrease of 11 squirrels from the 2015 estimate of 263.

“While we’d prefer to see squirrel populations continually grow, it’s not uncommon for them to fluctuate considerably from year to year,” said Tim Snow, terrestrial wildlife specialist for Game and Fish. “At this point, we aren’t immediately concerned with the lower squirrel numbers. We remain optimistic that our efforts are working to ensure the population has the best opportunity to flourish in the future.”

The squirrel survey is conducted each fall by visiting a random sample of known middens, which are areas where red squirrels store their pine cones.

Declared endangered in 1987, the Mount Graham red squirrel population peaked at about 550 animals in the late 1990s. It now typically ranges between 200 and 300 individuals.

Habitat losses caused by fire, insect infestations and poor cone crops caused by drought are considered primary factors influencing population size.

Contact reporter Doug Kreutz at dkreutz@tucson.com or at 573-4192. On Twitter: @DouglasKreutz