Critters Damage Crops

David Pacchioli
June 01, 1996

Every year, a sizeable fraction of the corn grown in Pennsylvania is eaten without being paid for—by whitetail deer, mostly, with a bit of assistance from blackbirds and bears. These and other critters chow down on other crops too: soybeans, for example, are a particular favorite of the state's groundhogs. Just how much of our annual agricultural product is lost to this al fresco munching, however, is open to debate.

"The studies done have been either small spot studies of individual farms, or paper surveys," says Margaret Brittingham, Penn State associate professor of wildlife resources. Damage estimates vary widely. A 1980 Penn State report, Brittingham says, approximated that Bambi and Co. cost farmers $30 million a year; a 1988 study sponsored by the Pennsylvania Farmers' Association put the figure at $96 million.

There being considerable interest on the part of both farmers and the Game Commission in getting an accurate count, Brittingham and Walter Tzilkowski, associate professor of wildlife science, in June 1994 received a $220,000 grant from the Pennsylvania Department of Agriculture to take a more thorough look.

Their approach, Brittingham explains, has two facets. The first was a questionnaire mailed to 5,000 farmers in March 1995, asking them to estimate their losses. The second was an extensive "on-the-ground survey" of over 200 farms around the state, completed with the aid of a sophisticated sampling technique devised by former Penn State statistician Colin Goodall. Goodall's system, Brittingham explains, allowed the surveyors to extrapolate from samples instead of inventorying each farm in its entirety. Even with this time-savings, she notes, the fieldwork took a traveling four-person team two full months in the fall of 1995 to complete. "It's a big project."

But she expects the extra effort to pay off. Combining the two methods, Brittingham says, will provide a check on each, and ultimately a better gauge of losses. "What we're hoping for is a relatively unbiased estimate of damage around the state, and also to identify patterns of damage. We'd like to be able to use this data to pinpoint problem areas and determine what controls might be effective."

Although her analysis is still incomplete, Brittingham says, some findings have already emerged. Sixty percent of the farmers who responded reported wildlife damage, with most calling their losses "moderate"—seven to nine percent of a crop. By assigning 1994 crop values to average loss figures, Brittingham and Tzilkowski have come up with an annual total loss estimate of $74 million for five crops: corn for grain, corn for silage, alfalfa, oats, and—as a representative of "high-value" vegetable crops—cabbage.

But average figures can be misleading, Brittingham warns. Some farms, particularly in the state's central ridge-and-valley region, experienced damage heavy enough to make them switch crops or even stop planting an area altogether. By contrast, many farmers in flat, highly settled Lancaster County suffered no damage at all. "The data will be more useful once we've had a chance to break it down by county," she adds.

Not surprisingly, farms close to wooded areas were reported hardest hit. "Also," Brittingham says, "farmers at least perceive bigger problems where adjacent land is posted 'No Hunting.'"

The field data, yet to be analyzed, may or may not corroborate that perception. If it does, Brittingham says, it might spur some new thinking about available controls on the deer population. The tactics most farmers currently rely on are less than ideal, she notes. Shooting deer (allowed with special permit) is time-consuming, and fencing fields adds maintenance headaches.

"If posted land turns out to be a big issue," Brittingham says, "maybe it will serve as an impetus for some of these lands to be opened up to some form of hunting. Or at least raise public awareness of the need for it."

Margaret Brittingham, Ph.D., is associate professor of wildlife resources, and Walter Tzilkowski, Ph.D., is associate professor of wildlife science, both in the School of Forest Resources, College of Agricultural Sciences, 321 Forest Resources Lab, University Park PA, 16802; 814-863-8442. Chief field technician for the reported study was James Zeidler. The study is sponsored by the Pennsylvania Department of Agriculture.

Last Updated June 01, 1996