"There's an unplanned experiment going on in the northern Rocky Mountains. What's happening is that spring is arriving earlier, and it's generally warmer and drier than usual. And that's messing with some of the fish that live there.

The fish is the iconic cutthroat trout. It's a native North American fish that thrives in cold, small streams. Explorer Meriwether Lewis of Lewis and Clark Expedition fame was among the first European-Americans to catch this spangly, spotted fish. He used deer spleen as bait.

It's relative rarity now makes it a favorite for catch-and-release anglers. But biologists have now found that it's in danger. The much more common rainbow trout is invading cutthroat streams and mating with the native fish. Ecologist Clint Muhlfeld says that creates hybrids."

Christopher Joyce reports for NPR's Morning Edition April 18, 2017. [2]