By Erik Skindrud, Sacramento Bee

OAKHURST – Deep in Sierra National Forest, field biologists Carrie O’Brien and Jodi Berg pushed their way up a mountainside.

There was no trail to follow, just GPS readings to guide them through incense-cedar branches and mats of mountain misery. After half an hour they reached their goal – a dead white fir tree.

This tree was special. Inside it, a mammal called a Pacific fisher was tending her young.

Experts want to know whether numbers are going up or down for the fisher, a member of the weasel family whose Latin name is Martes pennanti.

The forest dweller is a candidate for listing as threatened or endangered under the federal Endangered Species Act, and it’s been at the center of rhetorical and legal fights for decades over timber cutting in the Sierra.

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