Iowa seeing far fewer rattlesnakes

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Iowa’s timber rattlesnake population has declined more than 50 percent in the past 30 years, according to one of the vipers’ leading advocates, Department of Natural Resources Conservation Office Burt Walters.

Though the timber rattler has been protected throughout much of its Iowa range since 2002, Walters said he is “still pretty worried” about the snakes’ future.

Construction of homes and other development on the rocky slopes preferred by timber rattlers for their dens is the top threat to the reptiles, said Walters, who has been making as many as 60 presentations per year on the snakes’ behalf.

The suppression of fire on goat prairies — open grasslands on south- and southwest-facing Mississippi River bluffs — has encouraged encroachment by cedars and other shrubs, rendering the terrain less attractive both to timber rattlers and the mice, voles and insects they favor as prey, Walters said.

Other factors in the snake’s decline, he said, are poaching for the exotic pet trade and the increased use of pesticides and herbicides, which further limit their prey.

Timber rattlers are not classified as endangered or threatened in Iowa, according to DNR zoologist Daryl Howell, who monitors listed animal species. “We just don’t have enough data on their abundance and distribution to support a decision on listing,” he said.

Walters said he understands the irrational fear of snakes — and especially poisonous snakes — that once prompted settlers to kill them on sight. “I initially got interested in snakes because I was afraid of them and wanted to learn more about them,” said Walters, who did his senior thesis at Upper Iowa University on rattlesnakes.

Though a timber rattler’s venom could theoretically kill a person, such an occurrence would be highly unlikely, he said.

“The truth is, the timber rattler is a very docile animal. They don’t want anything to do with humans, so you’d really have to get in one’s face to get bitten,” Walters said.

Moreover, he said, the bite would likely be dry, meaning the snake would not release its venom.

And even if the snake injected venom, the bite would rarely be fatal, he said.

“Calm down, realize what happened, seek medical attention and you should be fine,” said Walters, who covers Clayton and Delaware counties in the heart of the timber rattler’s Eastern Iowa range.

Walters’ snake presentations to school, service and conservation groups helped create a climate of tolerance that led to the 2002 passage of a law protecting timber rattlers in 14 Iowa counties where they are most prevalent. Until then, state law classed timber rattlers with English sparrows as animals unworthy of protection.

Walters said timber rattlers’ communal den sites — usually in porous limestone outcroppings — are especially vulnerable to the depredations of poachers.

A poacher hitting a den site just before or after hibernation could wipe out nearly all the timber rattlers in an entire area, he said.

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