January 04, 2011
Pop! The loud snap of an acorn hitting dry leaves below me shattered the afternoon stillness, nearly sending me tumbling off my stand.
Pop! The loud snap of an acorn hitting dry leaves below me shattered the afternoon stillness, nearly sending me tumbling off my stand. To that point, everything in the little woodlot had been relatively quiet. But as the shadows lengthened and the temperatures started dropping, so did acorns, each striking the forest floor with a sharp report.
To someone passing in the distance, it might have sounded like a hunter plinking squirrels with a .22. To the deer, it must have sounded like a dinner bell, because it wasn't long before the first ones showed up. A pair of fawns trotted out of the underbrush and under the expansive overstory of a very large oak -- the reason I'd chosen this spot.
That stand has been one of my favorite and most productive over the last 20 years. Still, I don't hunt it every season. That's because it's only productive in years when there is a good acorn crop. Otherwise, it's just a spot in the forest.
The Mighty Oak
To both deer and deer hunter, oaks are probably more important than any other tree species; and perhaps more important than all other species combined. Food studies have shown that where they occur, acorns are far and away the whitetail's favorite food. That's not so surprising when you consider how well they meet the nutritional demands of deer fattening up before winter. That's also why there is a direct correlation between the quality of the annual acorn crop and how healthy deer are entering this critical survival period. It also determines how well (and in some instances, if) they come out of it, particularly in northern regions.
When it comes to their value to deer and deer hunters, not all oaks are created equal. Botanists group them into two general groups: red (or black) and white. There are differences in the morphology of their leaves, but the biggest difference between various species in the two groups is the way they produce acorns. White oak acorns require one year to mature. Red oak acorns require two years to mature. White oaks tend to drop acorns early and fast, while reds drop over a longer period. Red oak acorns are also higher in fats and tannins, while whites are higher in carbohydrates. So, which are better?
White oaks might seem the logical choice, because they're capable of producing a bumper crop of acorns every year. But that's only under favorable environmental conditions. A late frost, a cold spring or heavy rains during the pollination period could mean a failure in the white oak acorn crop this fall.
Red oaks are subject to the same successes and failures -- sort of. Because their acorns require two years to mature, there is a lag effect. A cold spring this year won't have much impact on this fall's nut crop, but could depress it next fall. Furthermore, mast-bearing trees may have both tiny first-year and larger second-year acorns present. Given favorable conditions, they can also produce some acorns every year; though it is unlikely they would produce large yields in consecutive years.
White oak acorns also contain fewer tannins, which makes them sweeter, and presumably more palatable. Biologists suspect that's why deer show a strong preference for white over red acorns where both occur. When they drop, it doesn't take the deer long to find the whites and vacuum them up, which makes a stand of white oaks a great spot for early-season bowhunting. But because they drop early and fast, and are gobbled up quickly, their importance is limited.
While the deer are gleaning white oak acorns, reds are dropping too. But the drop is more protracted. Combined with the whitetail's preference for white acorns, that means red oak acorns are available for a longer period, including later in the season, a critical period for survival.
The Answer Is...
So, which oak is better? The best answer is neither, or both. The key to healthy wildlife habitat is diversity. Having both varieties present is best, as they tend to offset each other in terms of availability. If you have a poor spring, you may still get some residual red oak acorns from the previous spring. The reds may be sparse next fall, but the whites may have a good year. It is only when you get several consecutive years of damaging weather that you have problems, but that's also a natural population control.
Seasonal differences in availability and preference also help. Where only red oaks occur, deer are on them quickly. Where both types occur, whites act as a buffer, ensuring more reds will be available later in the season.
Also, reds are higher in fat -- about 18 percent versus only 6 percent for whites -- an important source of energy. White oak acorns, meanwhile, have a higher carbohydrate concentration, roughly 82 percent compared to 60 percent for reds. Each helps deer meet different dietary demands in different ways. For the hunter, having both not only means healthier deer, it also means more options for where and when to hunt deer that are coming to feed on acorns.