By viewing the beard of a live turkey, you can easily tell whether the bird is 1 (jake) or at least 2 (adult gobbler). And for a bird in hand, you can tell whether the bird is a jake, 2-year-old gobbler or an older gobbler. A jake, obviously, will have a short — typically 3- to 4-inch — beard. The beard of a 2-year-old gobbler will have substantial amber coloration at the tips. A beard gets its black color from melanin, a pigment that colors and strengthens feathers. The newly emerging beards of young turkeys contain little melanin, so the bristles are amber-colored. You can hold a beard up to a light or window to see amber tips. If the tips are more than about 70 percent amber colored, the bird is 2. If there's little or no amber coloration, the bird is likely 3 or older.
Other than that, a beard doesn't tell you much about the age of a gobbler. If someone says they saw a 2-year-old based on the fact the beard was 7 or 8 inches, they are full of malarkey. Beards grow about 4 to 5 inches per year throughout a gobbler's life. Therefore, it's easy to see how a spring jake has a 3- to 4-inch beard, because he's been growing beard filaments for about 10 or 11 months. Likewise, simple math substantiates why most 2-year-olds can easily have beards that are roughly 9 inches, plus or minus a little.
So why wouldn't a 3-year-old have a 13- to 15-inch beard? When a gobbler stoops to feed or for any other reason, his beard hits the ground, and the ends of beard filaments are slowly broken away. The bristles wear off at the tip at about the same rate as the beard grows. Thus, a 3-year-old gobbler might "only" have a 9- to 10-inch beard. Heck, a 4- or 5-year-old gobbler might "only" have a 9- to 10-inch beard. That same wear and tear is what slowly breaks off the amber tips on the beard of a 2-year-old.
No matter what anyone says, the only good gauge of a gobbler's age past 3 is spur length.