November 5, 2009 - Dr. James Kroll is director of the Institute for White-tailed Deer Management and Research at Stephen F. Austin State. The man known as Dr. Deer has published more than 200 scientific and popular articles and numerous books based on years of telemetry-tracking whitetails.

He was one of the first deer hunting writers to back up theory with science and debunk many popular myths. As deer seasons open around much of the country, Kroll answered questions about America's most popular big-game animal:

Q: What are the primary weather conditions that cause whitetails to become more active?

A: Climactic variables that affect deer movements are temperature, humidity and barometric pressure. The perfect hunting day is one with less than 50 percent humidity, 35- to 45-degree temperature and a light breeze.

Q: How much less active does a buck become during daylight hours as he ages?

A: Once a buck reaches maturity, he might as well be a different species. A mature buck is 90 to 95 percent nocturnal. At an advanced age, he tends to become more foolish, exposing himself to harvest.

Q: At what age is a buck most likely to grow his largest antlers?

A: There are two ages in which antlers tend to be the largest. The first 4 1/2 years, when a buck becomes physically mature and nutrients that once were directed to body growth are redirected to antlers.

This is also the age when bucks fight their way into the breeding pool, which takes a heavy stress toll. As a consequence, they tend to grow smaller antlers the next year. After their peak productive age of 4 1/2 to 5 1/2, bucks often grow larger antlers because they're not stressed so much by breeding.

Q: How many does would you expect a dominant buck to breed in a season?

A: No more than eight does a year, though the average is probably much less.

Q: How much more active do bucks become during the rut?

A: The rut is made up of several phases. What most hunters call the rut is the chasing period, when bucks are visibly pursuing does. The greatest movement increase actually occurs during the pre-rut, when bucks are positioning themselves for breeding. The next-most active period is the chasing phase. The least movement occurs during peak breeding when bucks are "nailed down" with does. The next slowest period for buck movement is the post-rut, when bucks restrict movement to conserve energy.

Q: Most hunters can identify a breeding scrape. Are scrapes an important tool for deer hunting?

I pay little attention to scrapes. Most scrapes are worked at night in staging areas. I spend my efforts on rubs, which bucks use year after year. If you map out rubs, you can identify the buck movement patterns on the property where you hunt.

Q: How do hunters overcome a deer's sense of smell?

A: A deer has a sense of smell that's at least 100,000 times better than a human's. There is nothing you can wear or spray that will totally eliminate your odor. Paying attention to wind direction is the best tactic.

Q: At what age should a buck be deemed "undesirable" and removed as a "management buck"?

A: It's my opinion that the majority of deer hunters and landowners have no business culling deer. Only under a high-fenced situation is culling even practical. In those situations, I start culling bucks at 3 years of age and I focus on trying to remove them early, before the breeding season.