Watch Out for Big Red

It's March, and our thoughts turn to snakes. Well, in the case of St. Patrick's Day, it is the LACK of snakes that is significant. St. Patrick reputedly drove all the snakes out of Ireland. Specifically, it is said that he drove them all into the sea when they interrupted him while fasting. And indeed, Ireland is a snakeless land. In fact, Ireland is home to a single species of terrestrial reptile, the viviparous lizard. Modern science has challenged the story of Patrick's snake eradication efforts. There's no evidence, fossil or otherwise, that snakes EVER inhabited the isolated and chilly island.

In contrast, numerous species of snakes call Riverside home. One species is particularly noticeable – and notable. In my 40-plus years in Riverside, I have encountered the red diamond rattlesnake more times than any other snake. Crotalus ruber ("the red rattle") has a lot of features that make it easy to see. Adults are three to five feet long and about two inches wide, mostly covered with a pattern of large, white-edged rufous diamonds. The head is triangular. The tail is black and white striped and tipped with the eponymous rattle. Also, these snakes are not shy. They do not seem bothered by buildings, traffic, or nearby people when they enter the urban-wildland interface. On the other hand, red diamond rattlesnakes are generally not aggressive to humans. They would rather retreat than get nasty.

That being said, you wouldn't want to be bitten by C. ruber. Its venom is a witch's brew of dangerous enzymes. And while the venom is considered one of the least potent of the rattlesnakes, a bite is still a medical emergency. If untreated, the bite of the red diamond rattlesnake can be fatal.

Given that rattlesnake bites are potentially fatal, I wondered whether human fear of rattlesnakes is innate. Two anecdotal incidents did little for me to come to a conclusion:

A few years after I arrived in Riverside, I led a nature walk in our coastal sage scrub. When I pointed out a red diamond rattler several yards off the trail, most of the participants were pleased to observe the snake at a distance. An octogenarian departed the trail towards the serpent, lickety-split. One of the hikers called out, "Uh, Dad?...Dad?". I didn't wait. I sprinted and touched his shoulder when he was only three feet away from the slowly receding rattlesnake. He turned, annoyed, but grumpily skulked back to the trail.

Some years later, I was enjoying a picnic reception with colleagues at UCR on a grassy patch near College Building South. A fat and sassy red rattler was sunning itself on the top of a wall about 40 feet away. Most of my buddies were happy to take a safe look, but one particularly "outdoorsy" gal freaked out. "I gotta get out of here …" and excused herself.

With conflicting empirical data, I sought scientific information. Extreme fear of snakes is called "ophidiophobia" and is not common. General fear and respect of snakes is common, but not universal. Nature or nurture? Studies on infants have shown that they can recognize snake-shaped figures at an early age. And when they do, their pupils enlarge, indicating a stress response (but not fear). These and other data reveal that the ability to notice a snake is innate, but specific fear of snakes is learned.

Let's learn a bit more about Big Red. C. ruber's range is fairly restricted. Its northern most limits are the transverse mountain ranges and the coastal side of the peninsula ranges: Los Angeles, Orange, San Diego, western Riverside, and western San Bernardino Counties, extending south through the length of Baja California. Red diamond rattlesnake is unlikely to occur in highly urbanized areas. They prefer wildlands that supply them with their favorite foods: small mammals (rodents and bunnies) as well as reptiles (lizards and other snakes), and the occasional bird. Chaparral, coastal sage scrub, and invasive grasslands all do the job. Nonetheless, collection data show that C. ruber can easily wander into the built community when it is close to wildlands.

Despite their fearsome bite, red diamond rattlesnakes have their enemies. Roadrunners, king snakes, hawks, weasels, coyotes, bobcats, and badgers all find them to be a tasty meal. In particular, young snakes are targeted.

Young snakes are precocious. All rattlesnakes are ovoviviparous. That is, the red diamond rattlesnake doesn't lay eggs. The mother snake doesn't build a nest. The mama snake retains her eggs in her body where they hatch. She gives birth to five to twenty baby snakes that are good to go.

St. Patrick notwithstanding, with our increasingly warm weather, snake season is already with us. When you enjoy hiking our still-green hills, be on the lookout for Big Red. Fun to see, of course, but give the snake the respect it deserves!