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Backyard Wildlife: Why deer aren’t devouring your plants

Normally, the Triangle area supports about 35 deer per square mile – about 30,000 deer in Wake County alone.
Normally, the Triangle area supports about 35 deer per square mile – about 30,000 deer in Wake County alone. MCT

If deer sightings have been less common in your wildlife garden over the past few weeks, you are not alone. And there’s a good reason for that. Actually, two good reasons.

The first reason stems from something that recurs – at least to some degree – annually. In the fall, when oak trees drop their acorns, deer head for the forests to feast on their favorite food, becoming more or less distracted from our grasses, plants and other backyard fare. Turns out that the acorn’s healthy fats are a deer’s best insurance against the long, hard winter ahead.

The second reason for the dwindling number of deer sightings is more troubling, a disease known as epizootic hemorrhagic disease, or EHD, which has recently reduced the Piedmont’s deer population by about half – a downsizing that will likely linger for the next two or so years, according to wildlife biologist Greg Batts.

Deer become infected through the bite of a tiny flying insect often called a midge or no-see-um (although the scientific name is culicoides). Midges were prevalent this past spring and summer due to wet conditions, Batts said, leading to a surge in EHD cases from August through November. The outbreak started in Franklin County and moved out into Wake, Johnston, Durham and other areas as the summer wore on. Batts said his office received numerous reports of deer displaying signs of the disease, including weakness, swelling of lips and tongue, and eventually death.

On the up side, deer that survived the outbreak carry broad immunity against further infections and can even pass it along to the next generation.

It takes about five years for one generation of an urban deer population to be replaced by the next, Batts said.

“Because the last outbreak of EHD we had around here was in 2002, the deer had no inherited immunity,” he added. “Then the virus shows up again and we get a lot of midges this year and bam – a sizable outbreak occurs.”

Deer hunters are reporting a poor season, as well, with the harvest as much as 60 percent below average in some areas, Batts added. About 3,300 deer were killed by licensed hunting in Wake County in 2013, and 180,000 across the state. Normally, the Triangle area supports about 35 deer per square mile. That’s about 30,000 deer in Wake County alone.

Now, back to the acorn crop.

Our region has had two straight years of near-perfect seasons for the development of acorns (collectively known as mast) – principally, no late frosts to kill off tender spring buds.

“We’ve been doing mast surveys since the 1970s, and this year’s mast count was the second highest on record,” Batts said. “It has been an exceptional mast year.”

Thus, the deer were well fed and not as likely to be seen darting about in search of food, paying visits to our gardens, or plying the corn piles hunters set out for them.

Now that the acorn feast is winding down, you can begin to expect to see more activity from deer moving in and out of their lairs looking for food in the coming months.

And population numbers in herds hard-hit by EHD will be back up to pre-2014 levels by 2016, Batts predicted.

So don’t cross those deer-resistant plants off your spring shopping list. They’ll have just enough time to get established before being put to the test by fawns and their hungry parents next year.

Elder: wildlifechatter@gmail.com