Field Notes - Rattlesnake Poachers

Clearly marked restricted areas and surveillance by a team of DNR staff appear to have reduced vandalism and poaching from Minnesota's largest known population of timber rattlesnakes on state land.

Rattlesnake experts Dan Keyler and Barney Oldfield say poaching and den disturbances during the past decade have caused a 90 percent decline in timber rattlesnakes at Great River Bluffs State Park south of Winona. No incidents of poaching or habitat destruction have been reported since the fall of 2001, when new signs and regular surveillance of timber rattlesnake habitat began. Timber rattlesnakes are predators that live in the forests and bluff prairies of southeastern Minnesota.

They prey on small mammals such as mice, shrews, moles, rats, chipmunks, squirrels, and young rabbits. The DNR listed the timber rattlesnake as a species of special concern in 1988 and a threatened species in 1996. It is illegal to take, harass, or kill them or disturb den sites on state and private property.

"We ruled out every other possible cause-there's no evidence the snakes declined due to natural causes," said Keyler, who documented the population with Oldfield in 1990-91 and again in 2002-03. "What we have are reports of snakes being taken, boulders being moved, and den sites being disturbed."

One of only two venomous snakes in the state, the timber rattlesnake has been heavily persecuted in its southeastern Minnesota range since European settlement. (The massasauga rattlesnake has been documented only once in Minnesota, in Wabasha County in 1944.) Local governments paid a bounty to rattlesnake hunters in Minnesota until 1989, when a bill to repeal the authority to award bounty was signed into state law.

Fragmentation of bluff-prairie habitat by agricultural fields, roads, and houses also has harmed timber rattlesnake populations. Today, the timber rattlesnake is nearly extirpated in Goodhue, Olmsted, and Wabasha counties. Protection of the snakes is a joint effort of DNR Parks and the DNR Scientific and Natural Areas Program.

Surveying the park's 3,000 acres of potential timber rattlesnake habitat, Keyler and Oldfield captured and released 85 rattlesnakes in 1990-91. They recorded body temperature, length, weight, and sex, and marked the snakes' rattles with a dark stripe for identification.

Follow-up surveys in June 2002 and June 2003 showed an alarming decline. The researchers found only seven timber rattlesnakes in 218 hours of searching the known habitat.

Keyler and Oldfield documented many cases of human disturbance after 1990, Keyler said.

In 1991 Keyler and Oldfield found broken rattlesnake rattles, uprooted vegetation, and disturbed rocks at a den site. The next year Keyler and Oldfield met a man in the park who admitted to having taken four timber rattlesnakes that Keyler and Oldfield had marked for their study. After a visit from a DNR conservation officer acting on Keyler and Oldfield's information, the man agreed to release the snakes, which he was keeping in his house, back into the park. He was never charged with a crime.

In summer 2001, in one of the restricted areas, DNR staff found several large rocks pried from the earth with a log. Later that summer Keyler found trash in the area.

"It's difficult to say why people feel compelled to vandalize den sites and poach timber rattlesnakes," Keyler said. "Some people want to possess the snakes. Others, I suppose, would like to destroy them." A poacher who intended to sell snakes would probably go to Iowa, Missouri, or other places where states don't protect timber rattlesnakes."

Because timber rattlesnakes have a relatively slow reproductive rate, recovery of the park's population would likely take at least 10 years, said Ed Quinn, state parks resource management coordinator. Females are 5 to 6 years old before they give birth to their first litter and reproduce only every three to four years.

Quinn said the DNR will maintain the restricted areas to try to safeguard what remains of the timber rattlesnake population in Great River Bluffs. In addition, Quinn said, continued management of bluff prairies with measures such as controlled burns and brushing will help maintain high-quality habitat for timber rattlesnakes in the park.

Because relocated timber rattlesnakes often don't survive, reintroduction should be considered only as a last resort, Keyler said. "A reintroduction program must remain a low priority and then only after an ample amount of time has been dedicated to a natural repopulating of the park," he wrote in the 2002-03 survey report.

The timber rattlesnakes could repopulate, according to Keyler, if they are adequately protected from people.

Quinn hopes that greater public appreciation of timber rattlesnakes as an important symbol of Minnesota's wild areas and the laws that protect them will ensure that timber rattlesnakes continue to be a part of Great River Bluffs State Park and King's and Queen's Bluff SNA.

Anyone who witnesses people in the park's restricted areas, disturbing large rocks, or harassing a rattlesnake is encouraged to report it to their local law enforcement office or call the Turn in Poachers hotline at 800-652-9093.

Jason Abraham