Mast Crops Attract Deer
Deer hunters know that White Oak acorns attract foraging deer.
Dr. Leonard Lee Rue III, in his book, The Deer of North America, (Lyons Press, 1999) provides a detailed description of the dietary preferences and foraging habits of deer. Rue points out that deer, like cattle, are ruminants, with four-chambered stomachs. Ruminants are able to consume large quantities of low-protein foods quickly and then chew and digest them slowly. This permits deer to limit the amount of time when they must let down their guard against predators and feed in relatively open places.
During the summer months, deer forage on leaves and non-grass plants. When apples mature and drop to the ground, deer add fruit to their diets. They will also feed on farm crops, and suburban gardeners often wake to find that dining deer have devoured their plantings. However, according to Rue, deer will forsake most other food sources for their favorite food, the acorns of the White Oak.
White Oak and Red Oak Acorns Are Food for Deer
Although deer will eat Red Oak acorns, they much prefer those from the White Oak, as they contain less tannin and are less bitter in taste. Acorns are high in fat and carbohydrates, but low in protein. But, in years when the mast crop is plentiful, deer have no difficulty finding acorns in great enough quantities to provide adequate protein to their diets.
White Oak trees produce heavy crops only once every few years. Red Oaks, however, produce heavily every other year, effectively filling in when White Oak acorns are scarcer. Although deer prefer the sweeter White Oak acorns, they can readily digest other varieties.
Location and Quantity of Mast Crops Affect Deer Movement
After locating areas where White Oak acorns lie plentifully on the ground, the hunter must determine how deer will be likely to approach the feeding area. Deer are instinctively aware of their vulnerability while feeding, so they tend to feed, then take a few steps before putting their heads down to feed some more. The deer will prefer to face into the wind, in order to detect the scent of any predator that may approach.
Theories about what triggers the estrus cycle of do include the amount of sunlight, phases of the moon, and falling temperatures. The dropping of acorns to the ground, providing a boost of high-fat, high-carbohydrate nutrition, has also been put forth as a primary factor that sets the rut in motion. Once the rut is underway, bucks will enter the seeking phase, covering more territory and providing hunters with more opportunities for good shots at trophy deer.
Wildlife photographer and writer, Tommy Kirkland, writes in his article, “Deer’s Quality Nutrition: Hard Mast Consumption” (Ohio Valley Outdoors, November – December 2009) that “These high energy foods can really enhance the rut, causing a large number of females to be receptive to rut crazed bucks traversing the land.”
The image of “rut crazed bucks traversing the land” is enough to make any deer hunter eager to be up in the tree stand with bow or gun in hand. Scouting the territory and selecting a place with White Oak acorns on the ground might be the secret to getting a shot at the biggest, wariest deer in the woods.
What is a Mast Crop?
A mast crop is both a primary food for many organisms and fluctuates in availability from year to year. Graph 1 (Picture 2, adapted from “Evolutionary Ecology of Masting Trees”), shows that many tree species follow a coordinated boom or bust cycle where most trees bear an abundance of fruit in some years and almost none in others. The fruit of these trees forms a significant portion of the food for insects, large birds, and mammals.
The Recent History of Acorn Masting in the US
Although most locations in the US are finding a scarcity of acorns for 2008, Sacramento, CA is experiencing the heaviest acorn crop ever recorded there.
Table 1 (Picture 3) shows the locations and intensity of seed production during several recent years of acorn production. Most trees are only able to produce heavy crops one year at a time. Different oaks vary in the timing of boom years:
- Black oak (Q. velutina) have an approximately two year cycle.
- White oak (Q. alba), have a three year cycle.
- Red oak (Q. rubra), have a four year cycle.
The timing of these cycles is not precise. They will sometimes take more or less time than indicated. Although most years have a moderate crop, in a few years most species might produce an abundance of seeds, while in other years very few will and the mast crop will fail to feed the consumers that depend on the seeds.
Since most species of seed predators specialize on a certain type of seed, the population of a maple predator can increase in a year of low acorn output if there had been an abundance of maple seeds that year. The maple predators will not affect acorns if the oaks produce a bumper crop of acorns when the maple predator population is high. The same holds true for acorn predators and maples. Of course, some seed predators (such as the Gray Squirrel, Sciurus carolinensis) are opportunists and not reliant on a single source of food.
Local Effects of a Bumper Acorn Crop
Carl Stamm, a retired wildlife manager, found in Connecticut, after a heavy acorn crop in the fall of 2007, turkeys, Meliagris galloparvus, and white-tailed deer, Oedocilus virginianus, were absent from gardens during the subsequent winter. Little wonder. They stayed in the woods feeding on acorns. Even though acorns were eaten in abundance, many were still on the ground in January. Unless they lived near chestnut oaks during the fall of 2008, southeastern Connecticut gray squirrels were scurrying around scrounging a few nuts here and there for storage.