Discerning what motivates rattlesnakes is a lifetime’s work for researchers like William Hayes. So if he wants to introduce you to the biological complexity that makes them worth studying, be prepared to follow a deliberately cautious route climbing over rocks and stepping over logs.
Take San Timoteo Canyon, a river valley near the town of Redlands in San Bernardino County that offers all the comforts rattlesnakes need to multiply and thrive: rocky outcrops on which to bask in the sun , thickets of vegetation for camouflage and piles of ground squirrels for basking in the sun. to feed.
On a recent sunny morning, it didn’t take Hayes long to find what he was looking for: a red diamond rattlesnake buzzing with a fearsome drumbeat as it slithered through the tall, lush grass and, only a few yards away, a Pacific rattlesnake, its forked tongue flicking as it watched from the shadow of a bush.
“Rattlesnakes are among the most feared, misunderstood and abused animals of all,” the 62-year-old said, pointing to the venomous snakes. “However, they are not so different from us. They too have fears, emotions and find comfort in companionship.
William Hayes, a research biologist at Loma Linda University and an expert on Southern California rattlesnakes, has been researching rattlesnakes recently.
Recent studies have led Hayes and a team of mostly Loma Linda University researchers to the provocative conclusion that rattlesnakes are anything but simple instinctive killers. They are individuals in complex communities who exhibit a range of temperaments and emotions that can persist over time in different situations.
A year ago, the team discovered the first evidence that a stressed rattlesnake can find comfort in the presence of a close companion, or “friend,” leading to a healthy, stable heart rate, similar to the way humans calm down.
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Now, they’ve grasped a new explanation for the unusually high levels of defensive behavior among rattlesnakes on Santa Catalina Island: It’s worth rattling more, biting more often, and injecting more toxins on an island where they could be trampled or trampled to death by imported goats, pigs, bison and deer, according to a study published recently in the scientific journal Toxins.
“The results of this study unambiguously revealed a much greater defensive capacity in Catalina rattlesnakes compared to mainland rattlesnakes,” the study states.
This discovery is particularly significant because it suggests a paradoxical exception to the “island discipline”, a phenomenon observed by Charles Darwin 180 years ago: finches, sea lions and marine iguanas of the Galapagos Islands were more docile than birds, seals and the reptiles of the continent. Darwin attributed their docility to the lack of predators and large non-native ungulates in their native haunts.
An adult male red diamond rattlesnake.
That’s not the case in Catalina, about 22 miles off the coast of Los Angeles.
Humans are thought to have populated Catalina about 8,000 years ago, bringing with them large non-native mammals whose density “probably exceeded that of the continent in recent centuries and into the present,” the study.
Over the past three decades, the preserve that owns nine-tenths of the island has shot, trapped and shipped out all of the invasive goats and pigs, as well as nearly all of the bison that were literally eating away at the island’s native vegetation.
Now a plan to use helicopter-mounted snipers to kill a remaining population of mule deer that ranges from 1,500 to 2,000 individuals roaming the Catalina Mountains has sparked a storm of protest among residents of the popular tourist destination and has sparked calls to state wildlife authorities. block the flush.
Meanwhile, Catalina rattlesnakes prey on deer herds with all the noise and venom they can muster, according to the study.
“By introducing predatory and antagonistic mammals to Catalina, humans have made encounters with rattlesnakes more dangerous,” the study suggests, “a fact that should be appreciated by those who currently oppose the removal of deer from Catalina.
A mule deer doe crosses a hillside on Catalina Island.
(Allen J. Schaben / Los Angeles Times)
Julie King, co-author of the study and an expert on Santa Catalina Island ecology, said: “Rattlesnakes see deer as a threat that could crush them. »
“So they’ve developed language and social behavior,” she said, “that warns, ‘Hey, I’m here, don’t step on me or you’ll regret it.’ »
The study suggests that another potential cause of the unusual aggressiveness of Catalina rattlesnakes is that they are smaller – on average – than those on the mainland. Although smaller, they prey on native ground squirrels and deer mice that have formidable teeth and claws larger than those on the mainland.
“To minimize the risk of retaliation,” the study suggests, “rattlesnakes and other vipers have evolved unique strategies for acquiring dangerous prey, including releasing the prey immediately after the envenoming bite, followed by chemosensory searching. to move their meal, which often travels meters or more before succumbing to the venom.
The study highlights that these behavioral changes may increase “the risks associated with humans interacting with snakes in this population, and potentially suffering serious or even fatal envenomation.”
Gerad Fox, 42, co-author of the study, said: “Our findings, and the recent findings of others, have only scratched the surface of the rattlesnake’s personality. »
“There is so much more to learn,” Fox added. “Little by little, we are coming to better understand an important part of our natural world, a part that deserves our respect and protection. »
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