About the only thing certain about turkey hunting is that nothing is certain. That's what makes it so much fun. You never know when a big tom is going to get up in your face and gobble about how pretty he is.

By the same token, he's just as likely to turn tail and run or hang up just out of range. Texas toms can blow up just as fast as a spring tornado-and leave you just as weak in the knees.

Like I said, hunting them is fun.

Texas has the country's largest population of Rio Grande turkeys, which range most of the state west of Interstate 45. But Easterns have been coming on strong where the tall trees grow, with the result that spring turkey hunting is now allowed in most East Texas counties. There aren't many birds there compared to the flocks you'll find in the Edwards Plateau and South Texas, but hunting big birds in tall timber is an adventure every devoted turkey hunter should have. It's an exhilarating (and often frustrating) experience.

Shannon Tompkins, Houston Chronicle outdoor writer and veteran turkey hunter, shows off a trophy Rio Grande tom, taken with Ron Wood area outfitter Harry Wayne Cloud. Brownwood and Comanche counties afford some of the finest turkey hunting in the entire state.

I've hunted turkeys on both public and private land from the Panhandle to deep South Texas and from San Angelo to the Sabine. Every single hunt has been different. That's another reason turkey hunting is so much fun: Every tom you meet teaches you something new. Every mistake you make is an opportunity to learn. I've made enough mistakes to earn a graduate degree in "tomology," but I've managed to collect a few beards as well as an education. Maybe some of the things I've learned will help you do the same.

Eastern turkeys have the reputation of being more difficult to hunt than Rio Grandes, being less vocal and more wary. My limited experience with them seems to bear that out. Hunting on the Moore Plantation Wildlife Management Area (WMA) in the Sabine National Forest last spring marked the beginning of my education on Easterns.

Moore Plantation WMA was one of the first to be restocked with turkeys. However, numbers are still relatively low, and the dense forest makes hunting difficult. Easterns prefer mature stands of mixed hardwoods and pines with an open understory. Prescribed burns conducted regularly and at the right time are necessary to maintain the habitat to their liking. Unfortunately, the possibility of smoking populated areas often prevents the burns, and an emphasis to use burns for timber management rather than wildlife management also means burns don't always happen when needed, so turkeys may be thick one year and gone the next. Last year's hotspot may be a turkey dead zone this year. Always check with the Texas Parks & Wildife Department biologists in charge of public lands before making a trip to hunt Easterns.

Locating gobblers by giving crow or owl calls to make them gobble and then setting up and calling them in works much better on Rio Grandes than on Easterns. Veteran turkey hunters Charles Foster, Sr., and Charles Foster, Jr., of Houston use a method to hunt Easterns that is more reliable. They roost a gobbler at dusk, then return to hunt him the next morning. However, this is often difficult to do given the scarcity of turkeys. You have to do a lot of scouting and listening to catch a gobbler giving that one gobble at dusk when he flies up to roost.

Once a gobbler is located, says Charles Jr., "You'd better be there the next morning, set up and ready to call at least half an hour before he wakes up." Foster says he sets up within 100 yards of the bird, waits until he gobbles, yelps to make him answer and then yelps sparingly or clucks and purrs after flydown. Often the tom will not gobble after he's on the ground, so you must sit still, be patient and watch carefully for that red, white and blue head moving through the trees. When this method works, the hunt is usually over within a few minutes after legal shooting time begins. When it fails, it's a long day in the woods waiting for dusk to come so you can try to locate another gobbler.

In contrast, hunting Rio Grandes in the turkey-rich Hill Country or South Texas Brush Country offers nonstop action that begins before dawn and continues until a bird-or the sun-goes down. Whereas Easterns have so many trees from which to choose that they can fly up wherever dark catches them, Rio Grandes often roost in the same area, or even the same trees, night after night.

Locate a roost, set up in the right spot, and your hunt can be over before the sun comes up.

Two little words in that last sentence cause trouble far out of proportion to their size. Choosing the "right spot" to set up is no easy matter. It's my opinion that 90 percent of turkey hunting success is in choosing the right set-up, and 90 percent of choosing the right set-up is luck.

It helps to know a little about what's on a turkey's mind when he wakes up in the morning. First and foremost is always survival. That's why turkeys won't fly down until it's light enough to see if there's a predator down there waiting to pounce on them when they land.

Visibility is a primary key as to where turkeys will fly down. They prefer to land in an open area that does not offer cover for predators.