PAGING JARED DIAMOND:

US bison ranchers struggle to meet consumer demand (STEVE KARNOWSKI, 12/28/10, Associated Press)

Bison grow slower than other livestock, and a heifer can't have her first calf until she's 3, said Dave Carter, executive director of the National Bison Association in Westminster, Colo. Beef cows can have calves at 2. Also, many producers are finding heifers more valuable for breeding than eating, which means fewer bison going to market — at least temporarily, he said.

The tight supply comes after bison farmers spent much of the past decade aggressively courting consumers by touting the health benefits of the low-fat, low-cholesterol meat. Bison caught on, and even in the economic slump, prices haven't discouraged consumers.

"Now our challenge is keeping up with that demand," Carter said.