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Rattlesnakes on California's Santa Catalina Island have learned that it pays to be unusually aggressive

Louis Sahagún, Los Angeles Times on

Published in Science & Technology News

LOS ANGELES -- Discerning what makes rattlesnakes tick is a life’s work for researchers like William Hayes. So if he wants to introduce you to the biological complexity that makes them worthy of study, be prepared to follow a deliberately cautious route climbing over boulders and stepping over logs.

Take San Timoteo Canyon, a river valley near the San Bernardino County city of Redlands offering all the creature comforts rattlesnakes need to multiply and prosper: rock outcrops on which to bask in the sun, thickets of vegetation for camouflage, and loads of ground squirrels to feed on.

On a recent sunny morning, it didn’t take Hayes long to find what he was looking for: a red diamond rattlesnake buzzing a fearsome drum roll as it slithered through tall, lush grass and, just a few feet away, a Pacific rattlesnake, its forked-tongue flicking as it peered at him from the shade of a bush.

“Rattlesnakes are among the most feared, misunderstood and abused animals of all,” the 62-year-old said as he nodded toward the venomous serpents.“Yet, they are not all that different from us. They, too, have fears, emotions and find comfort in companionship.”

Recent studies have led Hayes and a team of mostly Loma Linda University researchers to the provocative conclusion that rattlesnakes are anything but just instinctive people killers. They are individuals in complex communities that show a spectrum of temperament 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 solace in the presence of a nearby companion, or “friend,” leading to a healthy, stable heart rate, similar to the way humans calm each other down.

 

Now, they have seized on a new explanation for the unusually heightened levels of defensive behavior of rattlesnakes on Santa Catalina Island: It pays to rattle more, bite more often and inject more toxin on an island where they could be trampled or stomped 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 substantially greater defensiveness in Catalina rattlesnakes compared to mainland rattlesnakes,” the study says.

The finding is particularly significant because it suggests a paradoxical exception to “island tameness,” the phenomenon noted by Charles Darwin 180 years ago: Finches, fur seals and marine iguanas on the Galapagos Islands were more docile than mainland birds, seals and reptiles. Darwin attributed their tameness to a lack of predators and large nonnative ungulates in their native haunts.

Not so on Catalina, about 22 miles off the coast of Los Angeles.

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