GLENVILLE, N.Y. — Covered in his old forest camouflage, Steve Balser proved he's nearly invisible to humans. His hunting partner walked within 25 feet and didn't see him.
"I'm just not that sure about deer," Balser said.
His suspicions are backed up by scientists who have studied the sensory advantages deer have over hunters. Hence the continuing quest for strategies and camouflage that will tip the odds in hunters' favor.
Balser's pants, jacket, hat and mask all have brown, gray and green patterns that resemble the autumn hardwood forests of upstate New York. While he can also sit quietly, the longtime outdoorsman is pretty sure that his human smell is a dead giveaway to wildlife.
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Researchers studying animal vision and behavior say that prey have certain evolutionary advantages in perception, triggering their decisions to run or hide. Science's understanding, based on both biological analysis and behavior, isn't complete, but it supports several hunter theories, including that superior sense of smell, which deer use to communicate, find food and avoid predators.
"The most important thing is to watch the wind. ... Anything downwind doesn't exist to your nose," said Dr. Karl Miller, a professor of wildlife ecology and management at the University of Georgia. And while deer probably hear only a little better than people, in the higher frequencies, they have a better sense of unusual sounds and large external ears that help them localize the source, he said.
Scientists say you also have to appear initially to be something that's not a threat.
That led to modern camouflage, evolving from red and black checked coats that broke up a hunter's silhouette to clothing patterns that mimic the fields and forests, to raggedy suits that resemble a fluttering leaf and brush pile, to digitally designed clothing meant to fool a deer's eye into seeing nothing recognizable at all.
"Based on some very preliminary stuff we've done, deer don't see quite as clearly as we do," said Miller, who is also a hunter. "They don't see 20/20. That's not their purpose — to see detail. Their purpose is to see movement."
That, said Miller, co-author of a 2008 paper on the visual specialization of white-tailed deer, is something they do very well. "They have a harder time identifying an object, but as soon as you move on a deer, it busts you," he said.
They also see far better than people in dim light and have a larger pupil. Like dogs and horses, they have a reflective layer behind the retina that causes light to hit their photoreceptor rods and cones twice. With big eyes on both sides of their head that don't constantly move like human eyes, they have a 300-degree field of vision, giving them an advantage in detecting motion even at the periphery, Miller said.
In their 2005 paper in the journal Equine Ophthalmology, researchers Paul Miller and Christopher Murphy identified the vision issue for prey animals, processing a vast amount of information for the important bits that require attention.
"A critical aspect of vision is that an object (a wolf, for example), is identified as separate from its surroundings (dense vegetation)," they wrote. "Because this distinction is so important for survival, animals (including humans) with normal vision, can 'see' an object if it differs sufficiently from its surroundings in any one of five different aspects: luminance, motion, texture, binocular disparity (depth), or color."
Cal Welch estimated he's seen hundreds of deer in 53 years of hunting and shot at least 20, though not the three that came within 25 feet of him last year during turkey season. "I've found that even wearing orange, when you don't move, the deer don't see you," he said.
He's also found he can raise his rifle or pivot very slowly without alarming the animals. He'd been told early by an old hunter not to wear anything shiny that can reflect light, or blue jeans, which make an unusual noise if they rub against something.
"Basically as hunters we talk to other hunters. Between you and me, there's a lot of BS that goes around. You really have to sort it out," Welch said.
There's scientific support for both points, that deer see shininess in the bright part of the spectrum, and they see color, though in a more limited range than people. They have photo pigments on their cones for blues and yellows, making blue blobs a likely cause for alarm.
"They don't see as far into the red part of the spectrum as we do, which means they don't see blaze orange the way that we do," Miller said.
It's probably as a less intense color, and there's probably no reason for hunters to avoid wearing it as a safety measure, since there are often a lot of oranges in the autumn woods, but you need to break it up with a pattern so it doesn't look to a deer like a large, strange blob, he said.
"Animals take inventory," said Dr. Jay Neitz, professor of vision science at the University of Washington.
"You want to be able to break up the pattern so whether you're not moving or you are moving, what the animal sees never turns into a recognizable form," he said.