HELENA — Pat Plantenberg had finished spraying weeds at an old quarry in the Spokane Hills east of Helena when he came upon a sight that stopped him in his tracks.
“Here’s two periscope sticks popping up out of the grass looking at me,” Plantenberg said. “They were ahead of me, swaying back and forth.”
Two male prairie rattlesnakes — each about 4- to 4½-feet long — were doing what Plantenberg later learned was a “combat dance.”
The dance is part of a mating ritual in which the snakes try to force each other to the ground when their paths cross in search of a female, said Bryce Maxell, the senior zoologist at the Montana Natural Heritage Program.
“Essentially, what rattlesnakes do when they leave their dens in the spring is to go straight-line distances out to forage,” Maxell said. “In the second half of the summer the males mate while the females forage. It’s like looking for a needle in a haystack to do these straight-line transects looking for a female.
“If they run across another male they’ll do this one-upmanship,” which is the combat dance.
Maxell added that they see the dance with other smaller snakes, which sometimes will have half a dozen males involved, sometimes wrapping themselves around a female.
Plantenberg quickly dropped off his spraying equipment at his vehicle and picked up his camera. He walked to within 10 feet of the snakes, and for the next 15 minutes he shot about a dozen photos.
“They didn’t care that I was there. They didn’t even shake their rattles,” said Plantenberg, who works for the Department of Environmental Quality. “They weren’t biting each other, just doing their dance.
“It was like they were arm wrestling. One would slip off the other then get back up. It looked like they were pushing each other over.”
Plantenberg added that the symmetry of the dance was “unbelievable.”
“It’s a once-in-a-lifetime experience,” he said.
Maxell and Roger Siemens, a retired U.S. Forest Service wildlife biologist who moves problem rattlers, said it’s rare to see prairie rattlesnakes do the combat dance. Neither has witnessed it.
“It’s a lot more common in other rattlesnake species,” Maxell said.
While Siemens believes that a female probably lay nearby, waiting to breed with the winner of the combat dance, Maxell said that’s not necessarily the case.
Siemens added that Plantenberg probably wasn’t in much danger of being bitten by any of the snakes, since — contrary to public perception — they’re not aggressive.
“They’d run away from him as fast as they could,” Siemens said. “One myth people believe is they think the snake will run down and bite you, but they won’t as long as you don’t threaten them. I have dealt with thousands of them over the years and have never had a problem.”
Maxell adds that people probably walk past rattlesnakes all the time and don’t even know it.
“To them we’re an 800-pound gorilla and are pretty dangerous,” Maxell said.
Now that the nights are getting colder and the days are getting shorter, Siemens said the snakes are starting to den up on south-facing slopes. They mate only once a year and the prairie rattlesnakes give live birth, as opposed to other reptiles that lay eggs.
“In the summer the eggs develop internally, hatch internally and give birth to live young,” Maxell added.