When lighting struck the Pinaleño Mountains in southeast Arizona at around 2:45 p.m. on June 7, igniting a 48,000-acre fire that reduced an ancient forest to blackened poles and stumps, a scurry of rare squirrels — 217 of the 252 left in existence — disappeared.

Some were fitted with radio transmitters that burned to ash; conservationists deduced their fates. They hoped others had managed to escape.

But for those 35 survivors — biological remnants from the last ice age — Jeff Humphrey, a spokesman with the United States Fish and Wildlife Service, was deeply concerned.

“Most of them have lost the cones they’ve stored for their winter nourishment,” Mr. Humphrey said. “How do we get them through this winter?”