“Most available devices were designed with little or no reference to the sensory capabilities of deer,” said UGA wildlife ecologist Karl Miller. “We’re trying to provide a more thorough understanding of the physiological factors that drive deer behavior in order to develop effective methods that have a basis in science.”
Deer-vehicle collisions are on the rise, with growing economic consequences. Insurance officials estimate that 1.5 million deer-vehicle collisions nationwide each year incur more than $1.1 billion in damages. And in 2006, State Farm Insurance Company reported a six percent increase—an additional 10,000—deer-collision claims.
In Georgia, the Department of Natural Resources estimates that some 51,000 deer-vehicle collisions occur each year. This makes it fifth in the nation, according to the Institute of Highway Safety. Pennsylvania is in first place, with Michigan, Illinois, and Ohio respectively ranking second, third, and fourth.
In their attempts to reduce the numbers of deer-vehicle collisions, virtually all states try to warn motorists by means of deer-crossing signs, modified speed limits, highway lighting, and driver-awareness programs. Meanwhile, some states also try to deter the deer themselves—using devices such as roadside barriers and roadside warning reflectors.
These studies were conducted at Berry College, near Rome, where the large wooded campus supports a thriving deer herd. For example, graduate student Gino D’Angelo, working under the direction of UGA wildlife researchers Karl Miller and Bob Warren—and Berry College animal physiologist George Gallagher—gathered data on warning reflectors. Their study, published in The Wildlife Society Bulletin, found that deer basically ignored the reflectors.
UGA audiologist Albert DeChicchis joined the wildlife researchers in testing deers’ hearing abilities in the lab. Master’s degree candidate Sharon Valitzski then took to the field, studying deers’ behavioral responses to experimental sounds emitted from a moving vehicle. They found that wild deer were not deterred by any of the frequencies tested—including “ultrasonic sounds” emitted from bumper-mounted deer whistles that manufacturers claim are audible to animals but not humans.
In another study, conducted at the UGA Deer Research Facility, researchers found that, contrary to popular opinion, deer can see in color, though their range is limited to the blue/green spectrum. While several reflector manufacturers claim that red reflectors scare deer because they mimic the glow of predators’ eyes, the study showed that deer probably can’t detect the longer wavelengths of red and orange. “Ironically, red is the most commonly marketed color for roadside reflectors,” said D’Angelo.
The researchers have discovered other aspects of deer vision that, while not yet applied, may ultimately inform the design of improved deer-deterrent methods. In their most recent study, the researchers discovered that deer have far fewer light-gathering cones—photoreceptors in the retina responsible for daylight and color vision—than do humans. The retinal cones in deer eyes are arranged in a horizontal band, which enables the animals to monitor movement across a broad horizon but not to see fine detail.
The team also found that deer’s eyes cannot change focus as objects move closer, which explains why deer often stand still as a vehicle approaches. “Their nocturnal eyes also make them much more sensitive to light,” said D’Angelo, “which may be why deer are ‘blinded’ by headlights.”
In the next phase of their work, the researchers will test alternate roadside barriers and “opaque fencing,” based in large part on the earlier efforts of Berry’s Gallagher. In his study published in 2003, deer stopped using an established feeding area when faced with a “solid” fence made of burlap, presumably because they are reluctant to jump a barrier when they can’t see the opposite side. This result suggests that specially designed screening applied to existing right-of-way highway fencing may offer an effective low-cost deterrent.
“This is just one of a number of studies that clearly indicate the importance of understanding how the anatomy and physiology of deer influence behavior,” said Gallagher. And such behavior, effectively modified by human intervention and ingenuity, may keep the deer off the roads—and enhance driver safety.
Research Communications, Office of the VP for Research, UGA
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