Patch reader Brent Morgan has three times, in three separate locations, spotted a black rattlesnake at night while walking his dogs. And the spooky thing, Morgan wrote in an email to Patch, is that none of the snakes has not given the usual rattle shaking warning in any of the three encounters.
Morgan posted the above video to YouTube of his encounter with the snake at Eaton Canyon and described it as a "rumored hybrid species, most likely Pacific and Mojave" with a neurotoxic venorm.
A 2009 article in Scientific American discusses the Southern Pacific rattlesnake and the neurological symptoms their bites induce. The article notes that there seems to have been an increase in recent years of bites from that rattlesnake relative to other rattlesnake types in Southern California and also suggests the possibility that the snakes' venom could be the result of interbreeding with Mojave green rattlesnakes.
The Southern Pacific rattlers also are known to have dark coloring as this page in the Aquarium of the Pacific website attests.