Having a 400-pound black bear living in the middle of the sprawling Louisiana State Penitentiary strikes Warden Burl Cain as a very good thing.

"I love that bear being right where it is," Cain said on Monday. "I tell you what, none of our inmates are going to try to get out after dark and wander around when they might run into a big old bear. It's like having another guard at no cost to the taxpayer."

The bear was first seen by an inmate crossing a road in the prison on Friday. It was taking a stroll near the center of the state's only maximum security prison, which is about 115 miles northwest of New Orleans.

The 18,000 acre prison is the size of Manhattan, Young said. Although most of it is run as a farm, about 3,500 acres in the Tunica Hills is mostly untouched piney woods.

Prison workers measured the bear's footprints, which were six inches in diameter, Cain said.

"Every inch equals 75 pounds, so that would make it about 450 pounds," Cain said. "The wildlife people told us they think it's a big female they've been tracking for a while."

Prison officials believe they have eight to 10 bears on the grounds, said Gary Young, head of the executive management office at the prison.

Maria Davidson, manager of the Large Carnivore Program for the Louisiana Wildlife and Fisheries, doubts there are that many, but marvels that even one was spotted in an area of high activity such as the center of the prison.

"Bears are actually very shy, their tendency is to run and hide," Davidson said. "If a bear is seen multiple times in one place there must be some kind of food for it there."

Although black bears are classified as carnivores, Davidson said 90 percent of their diet is vegetable matter. The 10 percent that is meat is mostly made up of bugs. Black bears in Louisiana primarily dine on berries in the spring, Davidson said.

As for acting as an unpaid prison guard, Davidson doubts that the bear would provide much of a deterrent to a fleeing prisoner.

"We've never had a predatory attack by a black bear in Louisiana, to our knowledge, on pets or livestock," she said. "As for a bear coming out and rushing an inmate, I don't see that happening."

Even if the bears don't discourage thoughts of escape, there are lots of other reasons for inmates to stay put.

Angola, as it's known, is in an isolated location, surrounded by the swiftly moving Mississippi River on three sides, and the rugged Tunica Hills on the other, which makes it difficult for a prisoner to run, even if he can get off the grounds.

There is also a substantial population of alligators, rattle snakes and vicious wild pigs on the grounds and there have been sightings of panthers, Young said.

The last recorded escape July 4, 2005, Young said. Although recorded as an escape by the prison, because the inmate managed to climb a fence and get through razor wire surrounding his living unit, he was tracked down by bloodhounds and thermal imagers and never got off the prison grounds.

"He was back where he belongs 36 minutes after he went missing," Young said.