Two 3-foot-long rattlesnakes are basking in the warm spring sun outside their burrow in a field at the Jennings Environmental Education Center. Just a couple of feet away, a small group of visitors watch intently.

Doug Oster, Post-Gazette A massasauga rattlesnake suns itself at Jennings Environmental Education Center. Click photo for larger image. Listen to the rattler What does a rattlesnake really sound like? Listen to the massasauga rattler as it sounds three warnings. (463K MP3) Doug Oster talks with biologist Ben Jellen about the rattlers' non-aggressive behavior. (365K MP3) Oster gets a surprise as he and Jellen follow the snake while it escapes into a burrow. (1MB MP3) Herpetologist Jellen describes where the snake can be found. (600K MP3) Jellen says the massasauga rattler can be found in fewer places these days and more study is needed to determine where it remains. (227K MP3)

There are no screams, no one clutching their children and, what's most amazing, no fear.

But herpetologist Ben Jellen, who happened upon the sunbathing serpents at the same time as the visitors, says their reaction to the grayish-brown snakes is neither surprising nor inappropriate.

"The snake itself is very shy, very reclusive, very docile," he explained. "People have a misconception of snakes, that they are aggressive and mean and want to bite people. That is completely not true. It relies on its camouflage. That is its main form of defense and it's very efficient."

These snakes also are members of an endangered species of rattlesnake in North America -- the massasauga rattlesnake.

Although the massasauga's bite is venomous, no deaths have ever been attributed to it.

Jellen, an endangered species biologist who works for the Western Pennsylvania Conservancy, has spent the past six years studying this rare snake, the last two of those in Western Pennsylvania. He's doing an inventory to determine how many still exist. It's the first analysis of its kind since the mid-1980s.

"Continued habitat loss and human persecution over the past 25 years have resulted in a need for another study to find out where these snakes are still occurring and which populations we've lost forever," Jellen said.

No one is sure how many massasaugas exist, either locally or nationally. In Pennsylvania, the snakes historically have been found in 19 localities in six counties, but now they can be found only in eight sites in three counties.

One site where the snakes actually seem to be prospering is at Jennings, a state park dedicated to environmental education that is situated 12 miles north of Butler. Established by the conservancy in the 1950s to protect a rare prairie flower called the blazing star, or Liatris spicata, the 220-acre park also is the only place in the country managing the land to help the snake.

Jennings is the perfect place for the snake, which thrives in the open fields of the wetland prairie, living in crayfish burrows. Sometimes called a "swamp rattler," the snake feeds on small mammals, reptiles and amphibians. The eastern subspecies has a range that extends from central New York and southern Ontario to Missouri and Iowa.

Pennsylvania also is home to a second species, the timber rattlesnake. As its name suggests, the timber rattler prefers heavily wooded areas.

	Doug Oster, Post-Gazette Endangered species biologist Ben Jellen has been studying the massasauga rattler for six years and hopes his work will provide information that can be used to protect the snake. Click photo for larger image.

One way to provide the open range the massasagua snake needs is by keeping the tree canopy clear with periodic, controlled burns, said David Johnson, manager of the Jennings center.

It seems to be working. Johnson said he sees positive signs of the reptile, despite the continued decline of massasaugas nationally. More snakes, bigger snakes and lots of babies in the fall are all signs things are going well at Jennings.

Preserving the habitat is one of the things that is most gratifying for him. "I think there's a great sense of satisfaction. We're working with a species that we're seeing dwindling all across the state. I don't see it dwindling here, and I take a great deal of pride in that," Johnson said.

He also has observed a change over the years in public attitudes toward the snake. People used to be frightened when they would see one. "Now, it's actually become a very popular thing," he said. "In fact our most watchable wildlife is not the wild flowers, but the massasauga rattlesnake."

		You can help Ben Jellen hopes to find undiscovered populations of the snake in Western Pennsylvania. If you have seen the snake, contact him via e-mail at bjellen@paconserve.org or by phone at 412-586-2356.

Observing the snake is a valuable teaching tool for him. "It's nice to show people a real endangered species, not something from South America or the jungles, but right here in their native Pennsylvania habitats," Johnson said.

Next spring Jellen will begin a project to track the movements of the snake. Massasaugas will be caught and taken to the Pittsburgh Zoo and PPG Aquarium, where radio transmitters will be surgically implanted. The reptiles will then be released back into the wild at the exact location where they were found.

Jellen will track and record the movements of the massasauga in an attempt to better understand it.

"Populations are in decline throughout its range and if things continue to go the way they have for the past 100 years, this snake will become extinct," he said. Listed as endangered in Pennsylvania, it is a candidate for federal designation as endangered.

"I would just like to see this snake survive. It is a part of our natural heritage, and the only reason that it is suffering is because of human involvement," Jellen said.