Pack rat middens reveal south-central Idaho plant history

IDAHO FALLS, Idaho (AP) — Scientists studying pack rat middens at the City of Rocks National Reserve in south-central Idaho have determined that the area’s iconic pinyon pine trees first arrived about 2,800 years ago and became prevalent about 700 years ago. Julio Betancourt of the U.S. Geological Survey has studied pack rat middens in the U.S. West and South America. He says the middens contain plants that grew thousands of years ago, with some middens at City of Rocks 45,000 years old. Experts say the middens give a snapshot of the local ecology over time. The U.S. Geological Survey has a database of pack rat middens for western North America.