The sun is setting over Yellowstone National Park--showtime for the wolf groupies who have gathered on a hillside. Peering through high-powered scopes, they watch two wolves trot across a grassy plain. Excitement sweeps the crowd as No. 302, a jet-black male, crouches as an antelope approaches. He fails to nab his prey, but the spectators are thrilled nonetheless. "I'm addicted," says Jonathan Johnson, who drives eight hours from Washington state at least once a month to watch wolves. "Once you see them, you're hooked."

Millions of tourists visit Yellowstone every summer to see grizzlies, elk and bison, but only the wolves have developed a cult following. Like sports fans, groupies can recite the stats, ages and histories of favorite wolves. The faithful travel from all over the world and gather in chat rooms to relay the thrill of seeing a pack take down an elk. At least 34 tour companies cater to wolf tourists; experts estimate that this niche tourism generates tens of millions of dollars.

Researchers chalk up this phenomenon to humans' love of dogs and the inherent drama of wolf packs. Alpha males and females struggle to maintain power and hold their clans together. Last year spectators mourned when a legendary alpha female was banished by her younger sister. "There's a soap-opera story line with wolves," says one biologist. And there are plenty of tourists eager to tune in.

Copyright 2005 Newsweek: not for distribution outside of Newsweek Inc.