Studies detail buck behavior

By Bob Frye 

Andy Olson sits with one of the mature bucks he captured
and radio collared in Elk County for a study looking at how
deer relate to Pennsylvania habitat.

Every deer hunter has had the same dream at some point.

They want to go into the woods and come out with a deer. But not just any deer. They want a big one with the kind of rack that makes the people who put together outdoor magazine covers drool.

What are the chances of pulling it off? Well, on the eve of Pennsylvania's archery season — it opens statewide Saturday — there's good news and bad news, based on two recent studies.

One was done of mature bucks within Pennsylvania. It gave some strong clues as to where you might find big bucks at certain times of year and how vulnerable they are when focused on breeding.

On the other hand, another study, done in South Carolina, suggests bucks — big and small — become increasingly hard to hunt with even the slightest hunting pressure.

The Pennsylvania study was done by Andy Olson of St. Marys as a University of Georgia graduate student.

He put GPS collars on 19 mature bucks — those at least 3¹⁄₂ years old — on a 7,000-acre tract of private property bordered by state game lands in northcentral Pennsylvania. He then tracked their movements. The collars provided locations for each deer on the hour in spring and summer and every 15 minutes during the hunting season, from October through December.

Olson's goal was to see how and where the deer moved in relation to habitat. That has been studied in a few other states before but never in the continuous hardwoods of Pennsylvania, he said.

It turns out big Keystone State bucks cover a lot of ground.

“What I found is that the average home range throughout the year is about 1,000 acres. I think it's larger than people really realize. It's larger than I thought,” Olson said.

They don't use that almost 2-square-mile area equally at all times of year, however. Their core areas were much smaller.

But bucks actually move more and cover more ground in fall than at any other time of year, he said. Food and females accounted for where they were likely to be.

The same bucks that frequented food plots and forest openings in spring and summer shifted to areas of mature hardwoods to feed on acorns starting in September, Olson said.

Later, during the rut — which Olson defined as the month of November — bucks are likely to wind up anywhere, he said. One walked 4 miles outside his home range, going up and down hills, then turned around and came back all in one day.

That was extreme, Olson said. Most bucks stayed within their home range even when seeking does to breed. But they move around a lot within that territory, he said.

“One thing I did notice, which was really cool, came from looking at movement in the rut versus pre-rut. Bucks moved up to eight times as much in daylight during the rut as before,” Olson said.

“So as a hunter, come November, if you can stay out there, you're going to increase your chances of seeing a mature buck by eight times.”

After the rut, bucks went back to food sources, he said.

The South Carolina study, meanwhile, showed that adding hunters to the landscape impacts deer movements greatly. It was done by Clint McCoy, then a graduate student at Auburn and now a deer biologist with the Ohio Division of Wildlife.

McCoy also put GPS collars on bucks from 1¹⁄₂ to 4¹⁄₂ years old. The collars recorded locations every 30 minutes.

The study area was privately owned, intensively managed for wildlife — with food plots and feeders — and limited to hunting by invited guests. Those hunters typically were driven close enough to their designated stands that they never had to walk more than 20 yards through the woods.

“So there wasn't much pressure, at least in the way you or I would think of hunting pressure elsewhere,” McCoy said.

Yet bucks proved very sensitive.

McCoy drew what he called a “harvest zone” around each of the established hunting stands.

He then examined how the number of hours a hunter spent on stand impacted the likelihood a deer would enter that zone during daylight hours and how that changed over time.

McCoy found that bucks learned to avoid those areas more and more as the season progressed. They were four times less likely to wander into a harvest zone by the end of the season than they were at the beginning.

Young bucks proved just as wary as did older — supposedly “wiser” — ones.

“Age was not a factor. It had no bearing on their likelihood to enter those zones, which was a surprise to us and probably will be to a lot of hunters,” McCoy said.

His study also showed bucks are slow to come back to a spot that has had a hunter. They exhibited “avoidance behavior” for up to three days after a stand was hunted, he said. It's wasn't until six days after a stand was hunted that deer again were attracted to that location.

Hunters would be wise to keep that in mind and perhaps rest a hunting stand periodically, he suggested.

“Trail cameras can be your worst enemy in that regard. You see a picture of that big buck, and you know he's there. You think, if I just sit in my stand long enough, maybe I'll see him,” McCoy said.

“Our research suggests that's maybe not the case.”