Tuesday, January 18, 2011

More on Minnesota Rattlesnake Habitat



HOUSTON COUNTY, Minn. — Rattlesnakes were a part of life for Ken Visger. The cold-blooded creatures slithered down to catch a few sun rays, winding up in his lawn, near the shed and on his doorstep. Sometimes they wound up under the blades of Visger’s riding lawn mower. His wife, Terry, lost two dogs to their bite. “People always said ‘Oh you’ll never find them in your yard,’” she said. “That’s where we found them.” Visger, 64, recently agreed to an easement that will help conserve the rattlesnake’s bluff prairie habitat in the hills that surround his farm. The effort should keep poisonous snakes away, Visger said. The 145-acre easement, held by the Minnesota Land Trust, requires regular maintenance of the fading ecosystem — a rare type of prairie that forms on steep, south-facing inclines of bluffs in southeastern Minnesota, southern Wisconsin, and parts of Iowa and Illinois.

The easement on Visger’s property is the first by the non-profit’s bluff Prairie Protection Initiative, funded by a $5 million grant from the state. The effort aims to protect as many as 500 acres of bluff prairie.
Snowy clearings dotted the south side of three hills surrounding Visger’s property, where trees and invasive brush were pulled, felled and burned to restore prairie. Visger worked with the Department of Natural Resources on solutions and hired a contractor who spent more than a month clearing overgrowth.
The change in wildlife was easy to see, Visger said. Restoration brought more mammals and more birds.
And, so far, the rattlesnakes seem content to sun in the freshly cleared bluffs.

“Now they have no reason to come off,” Visger said.
More than 9,000 rocky limestone bluffs line the Mississippi River in southeast Minnesota, supporting about 50,000 acres of bluff prairie — also called goat prairie — one of the rarest habitats in the state, said Jaime Edwards, a non-game wildlife specialist for the DNR. Many of the area’s sloping hills are filled with cedar trees and invasive brush like buckthorn that create a canopy over a landscape once speckled by open grassland and wildflowers.

“The bluffs in Winona are just horrendous with invasive brush,” Edwards said. “It’s depressing actually.”
The state has 100 easements on about 8,100 acres in its Native Prairie Bank program, according to department staff. Residents still own and pay taxes on the land and are responsible for conservation and land management.

Before European settlement, periodic fires kept cedar trees from dominating the bluffs, Edwards said.
An early land survey that predates Minnesota’s statehood describes “bold exposures of rock, with a grassy bank beneath,” and prairies mixed with trees.

“On summit levels spreads the wide prairie,” reads survey, conducted in 1854 for the federal government. “It’s long undulating waves stretching away till sky and meadow mingle in the distant horizon.”

Timber rattlesnakes — protected in Wisconsin and listed as threatened in Minnesota — rely on prairies to maintain body heat and use cracks in limestone to hibernate in the winter.

The rattlers establish a territory, traveling varying distances, finding sunny openings to warm up, said Bob Hay, a former herpetologist for the Wisconsin DNR. Hay tracked snake movements off and on for almost 10 years with surgically planted transmitters.

“Most of the snakes in Wisconsin require a lot of sunshine,” he said. “Canopy reduces the overall temperature and can reduce body temperature enough to influence breeding.”

Tree overgrowth forces snakes down the bluff to areas developed by the human population, increasing the likelihood of sightings and attack, Edwards said. Researchers found rattlesnakes in about 15 to 20 percent of 450 of bluffs surveyed in Minnesota.

In the spring, the DNR will put an easement on another 30 acres of Visger’s land. He is offering the easement to the state as a donation, Visger said. His own conservation work helped him see the importance of preserving the area’s natural wildlife, he said.

“These are the plans to restore what we had before we screwed it up,” Visger said. “We’re the worst invasive species of all.”

No comments:

Post a Comment