Native American tribes and environmental groups are expected to challenge the move to shrink the Bears Ears and Grand Staircase-Escalante National Monuments.

Native American tribes and environmental groups are expected to challenge the move to shrink the Bears Ears and Grand Staircase-Escalante National Monuments.

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The rule change ends a safeguard that had been in place for 50 years and could hasten the demise of imperiled animals.

© Dave Sanders for The New York Times