Farmers and ranchers may be inadvertently aiding and abetting one of their worst enemies, the feral hog, by providing supplemental feed for white-tailed deer and other wildlife, said a Texas AgriLife Extension Service wildlife expert.

But a new study conducted at the Welder Wildlife Foundation near Sinton showed that is it possible to design fencing that allows deer access to feeders while excluding feral hogs, said Dr. Billy Higginbotham, AgriLife Extension fisheries and wildlife specialist.

In Texas alone, feral hogs cause $52 million of damage to crops and pastures annually, he said.

"And that does not include damage to wildlife food plots, wildlife feeds and feeders, or to recreational areas like parks, golf courses and landscapes," Higginbotham said.

In an attempt to curtail the damage, landowners hunt and trap feral hogs, he said. But at the same time, Texas hunters and landowners put out approximately 300 million pounds of shelled corn annually, primarily for white-tailed deer, spending an estimated $50 million. Feral hogs crash the party by raiding the feeding sites and eating the corn, often preventing deer and other wildlife from visiting at all.

The party crashing does more than just deny supplemental feed to white-tailed deer and other wildlife. Better-fed feral hog sows are more likely to produce more piglets per litter, and those piglets have a higher survival rate, Higginbotham said.

Fencing seemed the answer to the problem, he said, but how high was high enough to stop hogs and low enough to admit deer?

To answer this question Higginbotham devised a cooperative study with Dr. Tyler Campbell, wildlife biologist and station leader at the U.S. Department of Agriculture's Wildlife Services-National Wildlife Research Center near Kingsville.

Higginbotham and Campbell enclosed deer-feeder sites with fences of three heights: 20 inches, 28 inches and 34 inches. All fences used six 16-foot long panels, staked with steel T-posts and arranged in a circular pattern around feeders. During July and August, remote sensing cameras, which are tripped by motion, were used to record deer and feral hog traffic. The cameras recorded traffic before the fencing was erected and then for two weeks after in late July and early August.

Before the fencing, the automatic cameras recorded 5.3, 3.1 and 4.7 hog visits per hour for sites no. 1 (34-inch fence), no. 2 (28-inch fence) and no. 3 (20-inch fence), respectively. Deer visits per hour were 0.8, 1.4 and 0.1 respectively for sites 1, 2 and 3.

Once the fencing was installed, all three heights limited feral-hog access, but the two highest fences excluded them completely. To a small degree, the 34-inch fencing and the 28-inch fencing limited some deer access as well, but the overall effect on deer traffic was minimal as they could easily jump the fences, Higginbotham said.

With the fencing, hog visits per hour were reduced to 0.0, 0.0 and 1.8 for sites 1, 2 and 3 respectively. Deer visits per hour were negligibly reduced to 0.66 from 0.8 for the 34-inch fencing, but actually doubled for the 24-inch fencing and more than quadrupled for the 20-inch fencing, he said.

And why the increase of deer visits for the two lower height fencing?

Higginbotham posits that deer started visiting the feeders once "the neighborhood improved" as the hogs were excluded.

"We don't know for sure but that's a good bet," he said.

Because of these results, Higginbotham and Campbell are recommending 28-inch fencing.

The 28-inch high panels worked as well as the 34-inch high panels at excluding hogs," Higginbotham said. "Therefore, 60-inch wide panels can be purchased and ripped lengthwise down the middle to create a least-cost exclosure."

The cost of the panels and T-posts was $115 for the 20-inch high fencing, $170 for the 28-inch, and $187 for the 34-inch, he said.

However, Higginbotham said, landowners should not use this data to reduce the standard height of trap cages, which is usually 60 inches.

"I have always believed that the height of a fence necessary to keep feral hogs out was lower than the height necessary to keep feral hogs in," he said. "We'll repeat the trials this winter to better assess whether the fence heights limit fawn access to the feeders."

The winter study will be conducted with the help of Duane Campion, AgriLife Extension agent for San Patricio County, Higginbotham noted.