Mild-mannered rattlers leave people alone.

Some rattlers prefer to lie low rather than rattle and attack, and thus pose less of a threat than most people realize, conclude two wildfire biologists who conducted field experiments in which they walked by and hopped over the snakes.

Kent A. Prior and Patrick J. Weatherhead of Carleton University in Ottawa, Ontario, inserted temperature sensors and radio tags into a dozen eastern massasauga rattlesnakes to monitor their movements through a national park in Ontario. During that summer, the team located some snakes every few days and either walked within 2 feet of the coiled animals, sometimes pausing for 30 seconds, or stepped over them. The snakes rattled in only 60 percent of the encounters and never tried to strike during these disturbances, says Prior.