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Deer chew off more corn than you think

Estimating the corn yield stolen by insects, diseases and other problems is usually not that difficult for university specialists or crop consultants. But have you wondered about yields consumed by deer feeding in your corn? It might be something to think about with the population surge of these four-legged critters in parts of Nebraska.

Scott Hygnstrom, University of Nebraska-Lincoln Extension wildlife damage specialist, has some estimates based on studies of actual corn feeding damage as well as simulated deer feeding experiments, the latter at a research plot in Mead.

At a field day this summer, he laid out a scenario in which deer feed during the tasseling-silking stages, the roughly 14-day reproductive period when deer are most attracted to corn plants, especially newly forming ears.

At a glance

• The rising deer population has an impact on Nebraska crops.

• Deer pressure is highest in the Platte, Elkhorn and Missouri basins.

• Hunting seasons have been expanded to reduce deer numbers.

One deer, feeding twice a day, may devour up to 4 pounds of corn. Over the two-week period, that’s 56 pounds, or 1 bushel.

“Now, pick the number of deer that may be part of that feeding herd,” says Hygnstrom. “If it’s 50, for example, feeding in that field, that’s 50 bushels.”

It all depends on deer pressure. Nebraska’s deer population has mushroomed in recent years in parts of the state, especially in the Elkhorn, Platte and Missouri river basins, according to Hygnstrom. He cites as an extreme the DeSoto National Wildlife Refuge along the Missouri River near Blair where he’s seen 200 deer feeding at a time in a field leased to an area farmer.

While Hygnstrom has not studied the extent of deer-feeding damage to soybeans, he demonstrated at a field day how the animals clip off blossoms during the reproductive stage, which eliminates formation of pods. He’s also heard reports of deer damage to sunflowers and alfalfa.

Other feeding periods

Deer damage at other corn stages was examined, either from actual feeding in a field near Valparaiso or simulated damage at Mead. Deer feeding at the six-leaf stage, in mid-June, had little impact on yield. The same was true later at the
V-12 stage July 1. “The corn plant can sustain damage at this time without a significant impact,” he says.

That changes at the reproductive stage when the corn plant is most susceptible to feeding. “Deer love corn at this stage. The ear is nutritious and highly palatable, attracting more deer to the field.”

Feeding drops off at the milk and dough stages, but can resume at maturity, especially if it’s a prolonged harvest, giving deer more time to feed on the mature ear.

What’s your deer tolerance level? Hygnstrom surveyed farmers in his home state of Wisconsin when he worked as coordinator of the state’s wildlife damage abatement and claims program.

“The tolerance level was 25 to 35 deer per square mile,” he says. “In that range, farmers surveyed indicated they could accept 10% to 15% damage to corn because they and their families hunted deer or perhaps they leased land for hunting. But, based on the survey answers, once damage exceeded 15% their tolerance level dropped to zero.”

Hygnstrom estimates the “social carrying capacity” for deer is 25 to 35 per square mile. “That’s what generally is tolerated in Nebraska.”

But in the Elkhorn, Platte and Missouri river basins, the numbers can be much higher — as high as 110 to 120 per square mile.

The impact of higher deer populations, beyond direct crop damage, is the rate of vehicle-deer accidents. He pegs the average cost of such an accident at $2,500 and, with 5,000 per year reported in Nebraska, that’s $12.5 million.

Expanded hunting

With mounting deer numbers and subsequent concerns from landowners, the Nebraska Game and Parks Commission has extended deer hunting seasons and liberalized some permit requirements.

Kit Hams, wildlife specialist at the commission, says that in 2010, for the second straight year, an October firearms season has been added for 60% of the state, running from Oct. 2-11. The permit fee is reduced from the normal firearms season. The permit is for two antlerless deer.

Increasing the harvest of anterless deer is a major goal of the commission and is part of several other permits allowed.

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“Our goal is to reduce the eastern Nebraska deer herd by 25% in the next three years,” Hams says.

Landowners can do their part, he adds, by requiring hunters who use their land to take two anterless deer before shooting a buck.

DAMAGING DEER: Scott Hygnstrom, Extension wildlife specialist at UNL, points to what’s remaining of a small ear that has been clipped off to represent damage from deer feeding. Deer are attracted to corn plants as ears form during the silking-tasseling stage.

This article published in the October, 2010 edition of NEBRASKA FARMER.

All rights reserved. Copyright Farm Progress Cos. 2010.