The University Record, May 7, 1996
Suburban sprawl pushes expanding deer herds into backyards
The herb garden at the Matthaei Botanical Gardens offers tasty greens for growing deer herds that biologists say are increasing in suburban areas.
Photo by Rebecca A. Doyle
Whether seen as a doe-eyed benign garden visitor or a large-sized garden pest, white-tailed deer are becoming more common on southeastern Michigan homesteads.
As abandoned farms in rural townships are developed into suburbs, the habitat deer once enjoyed and depended on is disappearing. With no predators save a few hunters, the deer population continues to explode, finding its way into yards and gardens.
"And just like the city raccoon that raids the trash," says Charles Cares, professor emeritus of landscape architecture, "the suburban deer makes the best of its situation by raiding gardens."
When food is scarce, deer will browse almost anything they find, Cares says, but generally are discriminate eaters. "Knowing their likes and dislikes is knowledge that can be used to help make a garden less attractive to these animals."
Deer seem to have a yearning for yew, especially Michigan's native species , Taxus canadensis, which is becoming quite rare in natural, undeveloped areas because of this menu preference. They also seem to have a strong passion for Thuja occidentalis (arborvitae or eastern white cedar), fir, the genus Chamaecyparis (false cypress also called white cedar whose Michigan species is usually found only in moist peaty areas) and rhododendrons.
"If you live in an area heavily populated by deer and you want your evergreens to be safe from browsing, stick with the spruces---boxwood is a safe choice where it is hardy," Cares says. "Deer not only endanger woody ornamentals, the popular large-flowered Trillium is one species that has become increasingly rare where there is a dense deer herd."
According to a bulletin published by Cornell University's Cooperative Extension Office, "Resistance of Woody Ornamental Plants to Deer Damage," deer will rarely damage barberry species, Russian olive or paper birch. But they do have a preference for Norway maple, redbud, ornamental species of euonymus, English ivy, some roses and most members of the rosaceae (apples, cherries, plums and other fruit trees).
That rosaceae family, of course, also includes roses and it is the rose garden at the U-M's Botanical Gardens for which the deer have developed a taste. Adrienne O'Brien, a horticulturist at the Gardens, hung bags of "tankage" in the rose garden last year hoping to discourage a herd of about a dozen. While the white bags of dried and ground waste products from the slaughter industry didn't add to the aesthetic value of the garden, O'Brien says they did seem to repel the browsing herd.
"Some people have tried hair, nylon stockings, Ivory soap or mothballs," O'Brien says, "but nothing is foolproof."
While the bags of tankage can be worked into the soil after they have lost their aromatic potency, it is important to change them often when there is a period of heavy rain or when watering heavily from above.
"Last year I gambled too long, and the smell wore off," O'Brien said. "And guess who came for dinner."
O'Brien suggests that the bags be changed after three to six weeks of use.
Whether or not a deer invades backyard gardens or ornamental plantings in the lawn depends on the prior feeding experience of the animal, its nutritional needs, weather conditions and the availability of alternative foods.
"Deer follow consistent feeding and movement patterns that can be used to predict where damage will occur," says Cares. "Some areas, even Nichols Arboretum, could probably withstand a lone forager, but a resident herd would be a disaster."