Texas

Supplemental feeding of white-tailed deer is a long-standing wildlife management practice in deer hunting areas, said a researcher at the Texas A&M University System Agricultural Research and Extension Center here. But knowing which animals were eating what supplements, as well as knowing how much they were eating, used to be impossible to determine.

"Supplemental feeding, like that aimed at producing high-quality bucks for the hunting industry, is being done mainly by trial and error," said Dr. Susan Cooper, Texas Agricultural Experiment Station wildlife researcher. "Those producing trophy bucks as part of a commercial deer hunting enterprise want to know that the feed they're using is the right feed for their 'target' animals. They also want to know how much feed is lost to 'non-target' animals, such as raccoons."

The most commonly used supplemental feeds are high-protein pellets, she said. Other supplements include shelled corn, cottonseed and legumes.

To get specific data on supplement preference and consumption, Cooper turned to a technology more familiar to the retail security industry than wildlife research: Motion-activated video. But instead of linking the video camera to a cash register, she linked it to a waterproof scale with a bowl of supplemental feed resting on it.

"Using this equipment, we were able to determine the time an animal spent feeding and its rate of food intake," she said. "It also let us calculate consumption by species, age and gender."

To get the needed research data, Cooper conducted two sets of tests.

The first test involved nine tame, hand-raised white-tailed deer--five adult does and four bucks--living in pens at the Uvalde center. Shelled corn, alfalfa-based 16-percent protein deer pellets and whole cottonseed were the supplements for this test.

A subsequent field test, using the same three supplements, was done on free-ranging wild deer and other wildlife at a private ranch near Sabinal.

Initial testing of the equipment with the tame deer at the Uvalde center began during the summer of 2003. The Sabinal field trials began in the winter of 2003-2004, when browsing materials for the deer were at a minimum.

"We set up the equipment so that the animal triggered a motion sensor which turned on the video camera," Cooper said. "Time and feed weight output from the scale were superimposed on the video output."

As each animal ate, changes in the weight of the feed were recorded. Once the animal left and the motion sensor was not further stimulated for 30 seconds, the system switched off and the scale stabilized for a final reading.

In her trials with the penned, tame deer, Cooper noted the following results:

--Bucks and does have similar intake rates when eating corn or pellets.

--When eating corn or pellets, tame bucks tend to feed for longer periods than tame does.

--Tame bucks ate about twice as much feed per visit than the does.

--Bucks have a stronger dominance hierarchy than does, with the dominant buck feeding for long periods before permitting subordinate bucks to feed.

--Does tend to feed together.

--Tame deer spent more time eating corn than pelleted feed.

--Bucks did not eat much cottonseed, but does ate more cottonseed than pelleted feed.

During her field trials with free-ranging wild deer and other non-target wildlife, Cooper found the following:

--Consumption rates of wild and tame deer eating corn and pellets were similar.

--When the feed bowl contained corn, wild deer--especially bucks--stayed much longer than tame deer.

--When the bowl contained deer pellets, mature wild bucks did not eat from it.

--Wild does ate pellets for longer periods than tame does.

--Yearling bucks ate pellets, but for shorter periods than does.

--None of the wild deer ate cottonseed feed.

--The most frequent 'non-target' visitors to the food bowl were raccoons.

--Black-tailed jackrabbits, eastern cottontails, Virginia opossums, rodents and birds also visited the feed bowl, but did not stay long. (No feral hogs were observed.)

"There are some wildlife management implications that can be drawn from this research," Cooper said. "For example, in the field trial study adult bucks didn't eat the pelleted feed. So if the aim is to maintain condition in mature bucks in winter, the money might be better spent on corn. But if you want to make younger bucks grow, pellets might be a better feed choice."

The use of video technology linked to a scale allows for better monitoring of individual animals and can help wildlife managers quantify animal feed requirements, she added.

"This is particularly useful in addressing feed loss to non-target animals," she said. "Having data on feed loss to non-target animals will allow for making more informed decisions on whether it would be cost effective to reduce the numbers of non-target species."

Comparative feed consumption among wild deer and other wildlife in the Sabinal field trial showed that adult bucks ate 19.3 percent of the corn, but no deer pellets, Cooper said.

"Most of the corn and pellet feed set out was eaten by does and yearling bucks," she noted. "Does ate 57.5 percent of the corn and 38.2 percent of the pellets, yearling bucks ate 13.8 percent of the corn and 52 percent of the pellets."

Feed loss to raccoons was 9.4 percent for the corn and 9.8 percent for the pellets, Cooper said. The raccoons did not eat any of the cottonseed, and loss of corn and pellet feed to non-target wildlife other than raccoons was minimal.

"Of course, you have to take certain factors into account when interpreting at this data," Cooper said. "For example, the wild deer probably had a greater motivation to feed than the tame deer, which had food available to them at all times. And social behaviors, such as the dominance hierarchy among bucks, also come into play."

The consumption of supplemental feed by deer and non-target species also varies with population structure and density, seasonal nutritional requirements, forage availability and the type of supplement, she added.

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A young deer approaches the scale linked to a motion-activated video camera. This equipment was used by Dr. Susan Cooper, wildlife researcher with Texas Agricultural Experiment Station in Uvalde, to determine the supplemental feed preferences and consumption among bucks and does. The research also provided data on how much feed was being eaten by "non-target" animals, such as raccoons. (Photo courtesy of the Texas Agricultural Experiment Station.)