Free-roaming dogs are also common in the four counties, where leash laws are nonexistent and fenced yards are few and far between. Thorn said the dogs' role in the deer herd's decline is probably greater now than it has been for quite some time.

"When deer populations are high, dogs don't have much success," he explained. "They'll trail a deer until they come across a hotter scent, then they'll take off after the hotter scent. When deer numbers are down like they are now, the chances of coming across a hotter scent are reduced. The dogs are able to stay on a single scent until they wear the deer down."

Thorn believes a recent change to the state's hunting regulations might also be contributing to the population loss.

"The provision that allows bowhunters to take an extra antlerless deer has created a shift in the number and sex of deer taken during the season," he said. "The kill used to be 85 percent bucks, 15 percent does. Now it's roughly 50-50."

With more does than normal being taken out of the herd, fewer are present for breeding. Again, Thorn said that the change by itself wouldn't be enough to make a significant difference, but when combined with the other factors it might be.

"All these things contribute to the end result," he said. "It's kind of a 'perfect storm' of circumstances."

The final factor in the equation -- and one over which biologists have absolutely no control -- is the area's annual mast crop.

"It wasn't too bad (in 2005), but the two years before that we had out-and-out mast failures," Thorn said. "You could hardly find an acorn on the ground. When there wasn't enough food, does weren't as productive. Instead of having two fawns as usual, they might have had just one -- or none."

As of now, Thorn's theories about the decline are unproven. So far, DNR officials have been content to examine evidence of the problem without delving deeply into the root causes.

To fully understand what's going on, Thorn believes he and other biologists should conduct a deer-mortality survey similar to the one currently being conducted on turkey gobblers.

"It'd be nice to do, if we could come up with the money to do it," he said. "We really need to get a handle on what's going on down here."

That would suit hunters such as Ballard just fine.

"We have a great trophy resource in these counties," he said. "We need to find a way to keep it going."