The obvious appeal of mouth calls is their hands-free use. Also, with diaphragms, you can make any turkey sound you can think of.

But the tone is definitely different than friction calls, and that can be either an advantage or disadvantage, depending on the preference of the gobbler being worked.

It's said that turkeys make between 28 and 30 different sounds, or combinations of sounds. Happily, hunters only need to know a couple of the basic sounds to be occasionally successful. However, most experienced hunters eventually learn to duplicate four or five of them, any one of which might help to fool a tom under certain circumstances.

The sound most commonly used in spring turkey hunting is the simple hen yelp. Depending on volume and the length of the series, it can be classified as the tree call, lost call or the plain yelp. The yelp is followed by the cluck, purr, fly-down cackle and cutting.

If you've never listened to turkeys before and don't happen to have access to a flock, you can purchase instructional CDs, DVDs or videos at well-stocked sporting goods stores or from outdoor catalogs featuring turkey-hunting gear. You can also pick up tips by joining the National Wild Turkey Federation (at www.nwtf.org) and getting to know local chapter members or other turkey hunters.

In addition, if a sports show or sporting-goods store is sponsoring a turkey-hunting seminar in your area, by all means try to attend.

Realize, however, that no one can tell you exactly when to employ a certain type of calling device to solve a particular situation as it unfolds. Even when all conditions seem to be the same, there are always unknown variables that can help or hinder your efforts.

Of course, if there were no variables and if there were black-and-white answers to every hunting scenario, turkey hunting would be far less challenging -- if not downright boring. As it is, trying to figure out the subtle nuances is what keeps the pastime fresh and interesting.

Being adaptable is very important in your calling endeavors. Even if you favor a certain calling device over the others, the time will come to put that call away and try something else. This is not rocket science, just common sense. If you know a tom turkey is in the vicinity, and if he's paying scant attention to your calling efforts, by all means get out of your rut and do something different.