They both like the temperature to be ‘just right’, of course! Puns aside – rattlesnakes, like many other animals here in the Sonoran Desert, practice a desert survival strategy known as avoidance. They refrain from exposure and surface activity when it’s too hot during southern Arizona’s summer months, and the cold limits their activity during the winter.

Spring time is rattlesnake time, with warm day time temps and cool evening temps creating ideal conditions for late morning to mid-afternoon activity during daylight hours. Summer time is also rattlesnake season, but the long, sweltering days are simply too hot to negotiate. Activity switches to almost exclusively nocturnal, with some movement in the early morning hours as they seek out cooler retreats below ground. Fall is an excellent time of year to observe rattlesnakes as well, as the sharp edge of summer’s heat yields to shorter, cooler day temps.

So what’s up with the cold months of Winter? Sonoran Desert winters are as varied in temperature as Goldie’s three bowls of porridge. They are often a vacillating medley of transient temperature fluctuations, and rattlesnakes have adapted to take full advantage of this! Most of our winters here in the Sonoran Desert have strands of warm days woven in with the tapestry of colder ones. Rattlesnakes, being ectothermic creatures that rely on ambient temperature to help regulate their body temperature, emerge briefly from winter burrows to warm up a bit before returning to their subterranean retreats.

We here in the Herpetology department like to say that rattlesnake season in the Sonoran Desert is January 1 to December 31; it’s year ‘round! So it’s not about day or night when it comes to rattlesnake activity; they are active both day and night as the temperature allows. To summarize, Spring is in the air, and rattlesnakes are on the move, going about their rattlesnake business. It’s not just about Spring though; rattlesnake season is most of the year here in the Sonoran Desert!

West Coast Rattlesnake (Crotalus basiliscus). Photo: Zack West

Tiger rattlesnake (Crotalus tigris). Photo: Zack West

Arizona black rattlesnake (Crotalus Cerberus). Photo: Zack West

Here are a few fun facts about rattlesnakes that, for me, made them more fascinating and less scary:

• Rattlesnakes can use any number of passive or active defenses when they feel threatened, but relying on their camouflage and motionlessness is often their primary defense. They simply choose to remain undetected when that’s an option.
• Rattlesnake mothers demonstrate maternal care, remaining with their live-born young until the neonates (babies) shed their skin for the first time. Then they all go their separate, solitary, slithery ways.
• Rattlesnakes have built-in water dishes! When they’re thirsty, they can coil up while it’s raining, and drink water as it beads or pools up on their bodies. Brilliant!
• Rattlesnakes have excellent memories, and they require this attribute to survive. They ‘map out’ their home range by exploring it, and they remember exactly where things are located within it. Me? I lose a screwdriver within arm’s reach when I’m working on my car. Hmmmf.
• Finally, rattlesnakes never choose to interact with us, our kids or our pets. That’s good news! We’ve never had a visitor here at the Desert Museum chased across the parking lot by a rattlesnake.
• Finally (really this time), there is no such thing as an aggressive rattlesnake. That human quality is not on their ‘hard drive’. They only know how to be defensive if necessary; never, ever aggressive!

Written by Howard Byrne, ASDM HIIZ Keeper.