Something had piqued his interest.

And then I heard it - the faint rumbling drone of an ATV as it negotiated the four-wheel drive road in the valley bottom. The buck heard it before I did; I was watching him through my spotting scope, him and his three companions as they fed in a high basin. But he quickly resumed picking at the ceonothus bush in front of him, unconcerned with the road hunters two miles down the mountain, well below his Sawtooth Mountain hangout.

The buck must have known from experience that he and his cohort were safe from hunters in the bottom, who rarely ventured off the road or away from their ATVs. As I watched these bucks and several other groups of deer, in addition to countless elk on opening morning of deer season last week, I felt extremely fortunate that we still have country wild enough and with few enough roads to provide security bucks like these need to grow big and old.

Buck vulnerability - or how susceptible a buck is to harvest during the hunting season - is not a new concept. Many situations lead to increased vulnerability, including habitat fragmentation, decreased hiding cover, liberal seasons, hunting during the rut, advances in weapon and equipment technology, and gentle terrain.

But the most significant factor leading to increased vulnerability is growing density of roads open to traffic. More roads mean more hunters, which mean less chance for a buck to make it through the hunting season.

In heavily roaded areas, bucks have little chance to escape hunting pressure and have little chance to grow old. In areas with few roads, bucks can elude hunters and have a better chance of reaching maturity. It's that simple.

In recent years, we've seen a dramatic increase in the use of ATVs. And because of little regulation on their use, many areas are now riddled with illegal trails, significantly reducing important security habitat for deer and increasing hunter access into areas that were previously difficult to get to.

Not surprisingly, we have noticed reduced buck numbers and fewer mature bucks in many deer herds.

To combat increased access and ATV use and buck vulnerability, Idaho Fish and Game has reduced permit levels, shortened seasons, eliminated some hunting opportunity during the rut, and adopted a motorized vehicle regulation in some units.

In the coming months, hunters will have to make some hard decisions regarding mule deer management. Fish and Game is revising its mule deer management plan, and the public will be encouraged to comment on it later this year. This plan will direct mule deer management in Idaho well into the future.

If hunters want the opportunity to pursue large bucks, they are going to have to make some trade-offs. One potential solution could be restricting the use of ATVs with road and trail closures. Another alternative might involve controlled hunts, limiting hunts to primitive weapons, or antler restrictions.

Here's a tough question: Which would the hunter rather give up, ATVs or the opportunity to hunt every year? Hunters can't have it both ways - big bucks just aren't found in areas with lots of roads and trails and lots of ATV access.

Country-western singer Chris LeDoux said it best when he sang about real cowboys, because they are still out there, "You just can't see him from the road." The same principle is true for big muley bucks, and the ones in my spotting scope that day seemed to know it.

Jake Powell is a wildlife biologist in the Southwest Region.