Research Shows Deer Can Duck Nearly Any Arrow

I killed my first deer a year later in 1973 when my fiberglass arrow flew at least a fawn’s length ahead of my doe, but the unlucky girl leaped into the arrow’s rainbow-like path and caught my Wasp broadhead with its heart at 33 yards.

I was shooting a 43-pound recurve back then, complete with wool silencers on the bowstring and rubber silencers beneath each limb tip. And yet, both deer jumped my shots like coiled sprinters blasting from the starting blocks at the pistol’s pop.

Hunting videos a decade later helped explain those misses.

Researching the Response
One man who has documented and agonized over such misses is Dr. Grant Woods, owner/creator of Growing Deer-TV and The Proving Grounds in southwestern Missouri. This past summer, Woods decided to do more than relive misses in slow motion on flat-screen TVs. A researcher by trade, Woods set out to learn how far deer plunge earthward at an arrow’s release, and where arrows flying at varying speeds could strike or miss a ducking deer.

Helping him was Darren Cummings, a Pennsylvania bowhunter and engineer, who created a unique machine that pinpoints the instant an arrow is released; calculates how long it takes sound to travel 20, 30 and 40 yards; and records how quickly a deer could drop at those ranges with arrows flying at different speeds.

To help assess how far deer drop when startled by a bowstring’s twang, they hung 9-inch water balloons—roughly the size of a deer’s vitals—from release mechanisms just in front of the targets. Using data that pinpoints how fast Olympic sprinters respond to starting guns, and how fast sound travels specific shooting distances, Woods and Cummings set the target’s release mechanism to drop the balloon upon detecting the bowstring’s twang.

A few explanations before proceeding: Yes, whitetails might respond more quickly to startling sounds than do elite Olympic sprinters, but no one has electronically timed deer responses so precisely.

And why water balloons? Deer can’t drop faster than the speed of gravity. Because their hooves aren’t attached to the ground, they can’t use their muscles to forcibly pull themselves down. Therefore, a water balloon falls at the same speed as a whitetail dropping its body to load its muscles to spring.

Woods adds this caveat: When a deer is scarfing up acorns or chomping low-growing plants, it will throw its head skyward with tremendous force the instant it hears a scary sound. That upward thrust of its neck and head acts like a cantilever to propel the deer’s body downward at speeds exceeding gravity’s pull. Deer can’t apply that force when their head is already up.

The Scientific Test
Which brings us to the Woods/Cummings tests. Woods reduced his compound’s weight to shoot arrows at 258 feet per second. His intern, Luke, shot an 80-pound bow that generated arrow speeds exceeding 308 fps. They also shot a compound bow generating 276 fps speeds.

The balloons didn’t drop out of the kill zone at 20 yards for any of the bows. Specifically, they dropped 2.5 inches by the time Woods’ arrow arrived at 258 fps, but only about a quarter-inch for the faster arrows.

At 30 yards, the balloon dropped 6 inches and beneath the kill zone for Woods’ bow, and 2.25 inches for the midrange bow, and 2 inches for the 80-pounder. Woods’ arrow likely would have spined a deer or flown over its back at that range.

At 40 yards, a deer could have dropped over 10 inches by the time Woods’ arrow and the other compound’s arrow (276 fps) arrived, and over 5 inches by the time the arrow arrived from the 80-pounder (308 fps).

Those results show how risky bow shots beyond 20 yards can be. Thirty-yard shots become gambles for slower-speed bows, and 40-yard shots get risky even for blazing-fast bows.

“These tests were eye-opening for all of us,” Woods said in a telephone interview with MeatEater. “You can get away with slight mistakes at 20 yards that you’ll never beat 30 yards or farther because they have more time to respond. At 40 yards, most hunting bows and crossbows can’t hit deer in the vitals if they react to the shot. It’s important to aim for the bottom third of the deer’s vitals at all ranges, and to closely evaluate—and mostly pass—shots 40 yards and farther.”

The 40-Yard Barrier
Woods said a buck distracted by a decoy, or one hindered by steady background noises like loudly “quaking” aspens or rustling red-oak leaves on breezy days might make some longer shots feasible.

In most cases, however, longer shots are too risky. “Too much can happen after 40 yards,” Woods said.

Even though it takes sound longer to travel 40 yards, it’s still going about four times faster than most arrows (1,125 vs. 300 fps), which continually shed speed with distance. Further, a deer ducking at 40 yards has more time to respond, which means it’s dropping faster than one at 20 yards because gravity accelerates the longer it acts on falling objects. Therefore, if a deer can drop 2 inches at 20 yards, it won’t simply drop 4 inches at 40. It could drop 10 to 12 inches or more, depending on several factors.

And if it’s head is down, don’t risk the shot. The more footage Woods reviews, the more he’s convinced that deer with their head down realize they’re vulnerable and keep their ears and nose on full alert. Couple all those factors with the “cantilever effect” noted earlier, and it’s nearly certain a head-down deer feeding at 40 yards can duck even the fastest arrow.

“I’m not saying you should shoot when a deer is alert and staring a hole through you. But if it raises its head to chew and casually look around, it’s probably more relaxed than when it’s feeding at shoe-top level. I don’t make any sounds to alert a deer to pick up its head. If it’s passing by close, I might grunt or squeak once I’m at full draw, but I shoot the instant it stops.”

Pressured deer also respond differently than relaxed deer. A deer’s day-to-day life makes some home ranges more stressful than others, causing them to be especially high-strung. Research on elk living among wolfpacks and deer living among high coyote populations shows these prey animals spend more time in guarded, full-alert, reactive postures.

“It’s hard to predict why some deer jump the string and others don’t, so we aim for that lower third of their kill zone, assuming they’ll react,” Woods said.

More Research Needed
As so often happens with research, Woods’ findings spurred more questions he hopes to address soon. He doubts, for instance, that deer are responding to the sight of lighted nocks headed their way, because deer were jumping bowstrings long before the advent of electronics.

He also wants to learn if arrow-flight sounds generated by various fletchings further heighten a deer’s reactions, and whether a sound’s volume affects deer responses. For now, Woods is certain about this: “I don’t think you can make a compound bow so quiet that deer won’t respond to the release. I’ve shot many bow brands at many weights, and I doubt any of them can be made too quiet for deer to hear.”

We’ll keep you apprised of Woods’ research as it unfolds.

Feature image by Captured Creative.