Live-streaming video cameras of rattlesnake rookeries are surprising scientists with new discoveries about the slithering moms-to-be that gather by the hundreds to give birth in the “mega dens” in Colorado and California. For one thing, researchers have discovered that the snakes sometimes share child-care of their “pups.” The young stay in the dens with their mothers until they venture out on their own, Dickinson College biology professor Scott Boback, who co-leads Project RattleCam, explained in an NPR interview. In another surprise, Boback has witnessed the snake flatten, then coil their bo…