Sunday, December 19, 2010

Deer Country 2: Know Your Adversary

Ever wonder why deer seem to prefer to browse on the youngest, tenderest shoots and leaves in your landscape?

The reason is that deer don’t have upper incisors (cutting teeth). Instead, they have dental or browsing pads. They bring plant material into their mouths with their tongues and pinch it off between their dental pads and their lower incisors. That operates best when plant material is relatively soft or herbaceous, not woody, so for efficient browsing, deer prefer new or soft plant growth.

Good-bye, pansies. Good-bye, hosta leaves. Good-bye, new growth on maple and redbud trees. Good- bye, azalea buds.

Now that you know about deer dentition, you’ll understand many of their seasonal dietary preferences for foods that are relatively soft:

Spring (April to June): Herbaceous (not woody) plants and grasses and then buds and shoots of shrubs and trees.

Summer (July to September): Herbaceous vegetation, young leaves, new growth of shrubs and trees, and gardens. My two September photos show (1) a deer eating leaves, but not the more woody branches, of a kousa dogwood and (2) doublefile viburnum branches similarly stripped of their tenderer leaves.

Fall (October to December): Fruits and nuts (called mast). Acorns may make up half of their diet. Then come bramble leaves (blackberries, raspberries), mushrooms, and gardens.

Winter (January to March): Evergreen leaves, deciduous bark and dry leaves, acorns and nuts, winter fruits, such as rose hips and sumac and poison ivy seeds.

Deer diet, of course, varies from place to place and year to year depending on plants available and ever-changing weather patterns.  Scott Aker, horticulturist at the U.S. National Arboretum, noted that no edible is really off limits: “Deer will attempt to eat almost anything if their population is high and they are running out of food. That happens most often in times of drought or near the end of a colder-than-normal winter.”

It’s almost winter now, so while there is little snow cover, local deer are browsing on the remnants of grass, clover, and winter weeds. It’s been a good acorn year, so they’re vacuuming acorns under the oaks. And, alas, they’ve already stripped the buds from two of our azaleas—buds which would have been next spring’s blooms.

If the snow covers the mast and low-lying herbaceous vegetation, local deer will begin to browse on food they generally ignore—such as the tough and scaly leaves of cedar trees. After last winter’s Snowmageddon, I watched several deer awkwardly rearing up to reach cedar branches. They grabbed the ends of branches and then shook their heads, trying to pinch off or pull off pieces of greenery.

You may have noticed that for almost half the year deer prefer things growing in “gardens.” Thank you very much, gardeners in deer country. Two thumbs up for your well-stocked salad bar—so soft, so juicy, so browseable.

In next week’s Deer Country posting, I'll recommend publications about deer management for your wintertime reading.

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