LANDOWNERS who set out feeders for white-tailed deer in East Texas wouldn't be too surprised if you told them they had a few unwelcome critters showing up now and then.
They might be amazed, though, at just how diverse a group of freeloaders arrives from dusk to dawn, says Extension wildlife and fisheries specialist Dr. Billy Higginbotham. "If you have feral hogs, they will come," he said. "So will raccoons, rabbits, crows, squirrels, rats and opossums. Along with this varied list of prey species come the predators. It is not uncommon to photograph coyotes and bobcats at feed locations as they stop by on their rounds to check on what's eating the corn on that particular night."
Higginbotham is not just making an educated guess about the size and range of the uninvited menagerie. He has proof - photographic proof. Hundreds of photos taken by automatic cameras in Angelina, Cherokee, Harrison, Houston, Nacogdoches and Trinity counties show everything from feral hogs to raccoons, trespassing humans, bobcats, foxes and even a rare, hairless coyote showing up uninvited at deer corn feeders.
For the last four years, Higginbotham has been collecting canisters of exposed film from infrared- triggered cameras set at deer habitats on more than 20 East Texas ranches varying in size from a few hundred to a few thousand acres. The pictures have provided census data on white-tailed deer feeding habits at a level of accuracy not normally obtainable by such traditional means as spotlighting.
"It's like having an observer posted 24 hours a day over 14 days for every quarter-section of deer habitat on the property. This observer never sleeps or whines - and makes detailed notes of all deer and other critters that visit the bait sites. Now that's dedication even the most die-hard deer enthusiast can't match," Higginbotham said.
In essence the idea is simple. Set up a camera that is triggered by either motion, the animal's body heat or its breaking an invisible beam of infrared light. But if the idea is to take a census of the number of bucks, does and fawns in a particular area, the idea has to be backed up with some fairly sophisticated science and statistics.
A study by wildlife researchers on a Mississippi farm supplied the background. Researchers from Mississippi State University. and Stephen F. Austin State University used infrared cameras on a 10,000-acre property during two-week periods in 1992 and again in 1993. Bait sites were monitored using a density of one camera per 160 acres.
The researchers were able to "photo capture" 100 percent of marked deer in 1992 and 88 percent in 1993. Using the Mississippi study data, Higginbotham can infer from the number of deer that appear in the camera's eye the total count and the proportions of bucks, does and fawns with considerable accuracy. The estimate is based on the number of buck pictures obtained.
Because of their antlers, it's easier to distinguish between individual bucks when there may be multiple pictures of each animal. Based on the data collected in the Mississippi study, the doe and fawn population is calculated from the buck count. During one study where the cameras were set up before and after hunting season, the difference between the counts matched the number of deer taken.
"I didn't expect it to be that accurate, and maybe it was a coincidence that the numbers agreed, but it suggests, I think, that the method is a highly reliable way to conduct a deer census."
There are a number of infrared-triggered cameras on the market that can be used to monitor deer feeders used to estimate whitetail deer populations. There are two basic designs. One is active infrared where the camera is triggered when a beam of infrared is broken by animals at the feeder. The other design is passive infrared. It relies on body heat and motion to trigger the camera.
Both designs are suitable for monitoring deer feeders, though each type has its advantages and disadvantages, Higginbotham said. Prices range from $250 to more than $400 for each camera and infrared triggering unit.
"This new technology has provided a methodology to obtain information on a deer population including density, sex ratios and fawn production. I am convinced that it is one of the most valuable deer management tools to come along in many years."
Higginbotham prefers to set up the cameras on established bait sites where corn is fed. The feeders can be either the automatic type or covered troughs. If there are enough feeders distributed fairly evenly across the property, he will use them as the camera locations.
As useful as the automatic cameras are to take a deer census and manage wildlife, many landowners find it a shock to see just who is coming to dinner.
"For one, it's extremely disheartening to see the number of buck visits to feed sites only between dusk and daylight. The more mature the buck, the less likely they are to make an appearance during daylight hours," Higginbotham said.