From every crack in the limestone bedrock, snakes slither by the thousands, some tangled into balls, rolling over rocks and tree trunks, starved for love after hibernating through the seven-month Manitoba prairie winter.
Dozens of sex-crazed males wrap themselves around females in hopes of getting chosen to mate, watched by crowds of tourists who have trekked three miles on foot.
"It's a snake ball! It's a bowling snake ball!" yelled Michael Mohoney, clutching a handful of serpents on a visit for his eighth birthday.
Resembling mythical Medusa's snake hairdo, the tangles of red-sided garter snakes are one of the more unusual wildlife occurrences of North America, attracting thousands of spectators during the monthlong migration.
"There's nothing else out here but the snakes," said Darlene Herron, who sells snacks from a trailer in the parking lot of the remote region between Lake Winnipeg and Lake Manitoba, 420 miles northwest of Minneapolis-St. Paul, Minn.
The crowds start showing up on Mother's Day, she said, though, "I don't know why anyone brings their mother to the snake dens."
Nobody knows exactly how many red-sided garters come out of the Narcisse snake dens each spring. A conservative estimate is 50,000. They are harmless, yellow-striped with red markings, and 18 inches to three C feet long.
The snakes go five to eight feet underground in the fall to keep from freezing, spending months jammed in dank, dark crevices with no food beneath the frost line.
When warmer temperatures beckon, they climb out hungry for frogs and toads to eat and the chance to mate with a longer, thicker female.
Dave Roberts, the Manitoba Conservation wildlife technician in charge of the Narcisse dens, explained how males will swarm a lone female, flicking tongues on her back to detect the pheromone that is their aphrodisiac.
Once the female has chosen a male, the mating ball unravels and the spurned males look for another partner. Baby snakes are born in the late summer, usually 20 to 50 at a time, with an estimated 2 percent surviving to adulthood, Roberts said.
Though he knows the most intimate details of snake anatomy and behavior, the 47-year-old Roberts says some mysteries remain.
"What mechanism occurs that causes a female to be receptive or not receptive?" he wondered out loud as a thick damsel charged across the bottom of a den, at least six males creeping up her back.
Why do some males also give off pheromones that attract other males? Perhaps to confuse rival suitors, Roberts suggested.
The spring migration occurs in a region of limestone quarries where mining was prohibited in 1982 and four of the snake dens were declared part of a larger wildlife management area.
Inwood, the nearest town, has a stone statue of two red-sided garters in its center, and a sign depicting the species marks the entrance to the parking area on Highway 17.
Culverts have been dug beneath the road for the snakes to avoid crossing the pavement.
"Years ago," Herron recalled, "you'd come down here and that highway'd be slippery with snakes."
Entry is free and guides, mostly college students studying park and wildlife management, explain the snakes to visitors and help children catch and hold them.
At one den, 5-year-old Leanna Rempel gestured with a snake in her hands at 6-year-old sister Cassidy, who recoiled at first but then had the reptile sliding along her arm.
"It's a great opportunity to pass on information about these snakes and their stewardship," Roberts said. "We try to teach a little more tolerance of the fact these creatures live around us."