Biology Basics

    Understanding how a turkey’s anatomy and senses all work together — and against you — can make you a better hunter.

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    By Spencer Neuharth

    Imagine a blind man from another continent arrived in the United States, suddenly received the gift of sight and was then introduced to all the wild game of North America. An elk would surely impress with its massive antlers and huge body. A grizzly would definitely excite with its powerful size, beautiful fur and sharp teeth. And mule deer would absolutely amaze with their huge ears and bounding movements.

    Wild turkeys, on the other hand, would make a bad first impression. Their oversized bodies mounted on tiny sticks for legs make them look like a walking coyote snack. To top it off, they have some mutant features that appear to be designed by a cruel creator, like the hideous snood and repulsive wattles that are somehow attached to their porous, color-changing head and neck.

    If you told the story of how the wild turkey was once in the running to be our national symbol, he’d laugh at the nonsensical statement. If you then explained that they’re one of the most difficult species to hunt, he’d roar even louder.

    Anyone who remembers his or her first turkey hunt can relate to that type of arrogance. These wild birds are one of the hardest to pursue, and it’s all thanks to the biology that defines them. Their eyes, ears, feathers, legs and brain are ideal for eluding predators, especially humans.

    Eyes

    Turkeys have some of the finest eyesight in the animal kingdom, which is a reputation they’ve had for a long time. J.D. Caton perfectly sums up their vision with a folky sentence from his 1869 entry in The American Naturalist where he states, “It is a saying among old hunters that it [a turkey] can detect the human eye looking through a knot-hole from the inside of a hollow tree.”

    Modern-day literature agrees, and Scientific American states that a turkey’s eyesight is three times greater than a human with perfect 20/20 vision. In addition to their incredible visual acuity, turkeys have a 270-degree field of view. This is impressive on its own, but when you consider how a turkey strategically bobs its head and rotates its neck, it’s almost constantly taking in what’s going on a full 360 degrees around it.

    Most birds see in color, boasting of the most complex retina of any vertebrate according to a 2001 journal from Elsevier Science. Turkeys are no exception, relying heavily on color vision to find mates and detect predators. They’re able to do this because their eyes are composed of seven different types of photoreceptors and six different types of cones. For comparison, humans only have four different types of photoreceptors and three single-cones.

    One of the cones that turkeys possess has spectral sensitivity to wavelengths near 400 nanometers, which falls in the UV-light range. This extended view of color allows them to pick up things that humans can’t, such as the phosphates in laundry detergent that brighten clothes. The result can often be a bright, blue glow around otherwise camouflaged hunters who aren’t mindful of their laundry habits.

    What turkeys lack, though, is the ability to see well at night. The abundance of cones that allows them to see such detailed colors means that they lack rods, which are the visual cells associated with night vision. This is why turkeys are often overcautious with their roosting habits, gaining elevation before the sun sets and then not flying down in the mornings until after first light.

    Ears

    Their lack of low-light sight is why it’s absolutely imperative that turkey hunters are set up early. However, this doesn’t mean you can wander too close to the roost in the dark, because turkeys still have a great sense of hearing.

    “Their hearing supplements vision by attracting attention to the source of sound,” Bob Eriksen, a retired turkey biologist, told the National Wild Turkey Federation.

    This means that a turkey’s first line of defense is their sight, while their ears aid in their elusiveness. This second-fiddle sense is obvious to even uneducated observers, who would notice their lack of pinna, which is the external part of the ear that we often associate with mammals. The purpose of a pinna is to funnel and concentrate sound waves, something that turkeys struggle to do.

    According to Dr. Jacquie Jacob from the University of Kentucky, the rest of their ear biology is fairly similar to a human’s. Like humans, turkeys have an outer ear, middle ear and inner ear. Their outer ear is the small hole in the side of their head, which is less efficient than ours at gathering sound. Their middle ear is separated from the outer ear by their eardrum, which vibrates from the sound waves. Those vibrations are transferred from the middle ear to the inner ear, which is responsible for the initial analysis of the vibrations.

    However, birds also have a columella, a single structure of bone and cartilage, in their ears, which speeds up the process of getting vibrations to the part of the brain that recognizes it as sound. This quick progression means that birds literally hear faster than us. While we hear sounds in bytes about 1/20 of a second long, birds discriminate up to 1/200 of a second. That gives turkeys the ability to hear much shorter notes, where one note to us equals 10 notes to them.

    All that points to why we fawn at great turkey calls and callers. Your yelps might sound spot on to you, but the masterful ears of a tom tell him otherwise.

    Feathers

    If a turkey learns through visual or audible cues that something isn’t right, it’s likely they’ll leap into flight. Helping them defy gravity is their pneumatic skeleton and strong muscles, along with their brilliant feathers.

    The feathers that benefit their flight the most are, for obvious reasons, called the flight feathers, which turkeys are sort of famous for in the world of ornithology. Their flight-feather recognition comes from the fact that they have one of the lowest wing-loading scores and are one of the heaviest flight birds in North America.

    The equation for wing loading is body mass (grams)/wing area (centimeters squared), which is one of the best indicators of how a bird lives, according to The University of Waikato of New Zealand. A turkey’s wing-loading score is 0.96, which is about as low as it can go while still maintaining the ability to fly. If wild turkeys were any heavier or had smaller wings, they’d resemble the flightless domesticated turkeys that are easily picked off by predators.

    While flying may look like a real chore for turkeys, they’re actually quite good at it. They’re capable of going over a mile at a time by alternating wing beats and gliding. They still have their limitations, though, and can only carry on with continuous wing beats for a couple hundred yards. Once they gain flight, the distance they go hardly matters, as they’re capable of reaching speeds up to 50 mph.

    However, don’t get too caught up on the flight feathers, as adult turkeys have more than 5,000 other feathers that cover their body that fall into functional categories such as body covering, insulation, waterproofing, flight, sensory organ protection, display and recognition.

    Turkeys maintain their many feathers through practices such as dusting. Dusting is an alternative to bathing where water resources are limited. When a turkey dusts, it’s working dirt into its plumage with the goal of getting rid of excess oil. This keeps their feathers in top condition, while secondarily giving them a duller camouflage that blends in better in the dense woods.

    Legs

    It’s in those dense woods where turkeys can struggle to gain flight. If they attempt to do so, they risk damaging one of their 30 valuable flight feathers on a branch or twig and handicapping themselves in future situations. Instead, a turkey can opt for using its legs for a getaway, which is a nice alternative when you check the stats.

    Wild turkeys have been documented running up to 25 mph; that’s only 3 mph slower than what Usain Bolt was clocked at during his gold-medal performance in the 100-meter dash in the 2016 Olympics.

    There are a couple factors that help make turkeys ideal track stars. One of them is how their tendons are structured. To better understand how turkeys cover so much ground, a study was done to observe the impact that their tendons take when compressed. To do this, researchers dropped turkeys from 5 feet in the air and observed the landings with foil-strain gauges glued to the turkeys’ legs.

    Observers were amazed when they saw the results, noting that a turkey’s tendons protect surrounding muscle fibers by absorbing energy from a hard landing before releasing it back to surrounding muscles more slowly. This process is perfect for a specimen that needs to make quick escapes or catapult itself into flight.

    The architecture of a turkey’s legs also makes them great land birds, according to a scholar who has spent nearly a decade working with speedy birds. They have backward “knees,” which are really their ankles, but that’s common among avian species. What separates them from the flock is their locomotion-friendly build of long legs and high muscle location.

    Similar to fast land birds, such as ostriches and emus, turkeys have long legs with the majority of their thigh muscle mass packed closely to their bodies. This allows them to swing their lightweight legs faster, giving them a longer and faster step, unlike humans who have knees and ankles that are quite far away from the rest of their body.

    Brain

    The epicenter of it all, though, is the turkey’s brain. They’ve basically been dealt the genetic lottery for a species of prey, making it easier for them to get away with having a walnut-sized control center. Size isn’t everything, though.

    Turkeys have a terrible reputation for being a dumb animal. We often hear of them staring at the sky for extended periods of time, even in the pouring rain. This is a condition called tetanic torticollar spasms, which causes turkeys to throw their heads back and pause all action. However, this is only found among certain breeds of white domesticated turkeys and has never been observed in the wild.

    With that nasty stigma out of the way, we need to give them credit for being quite intelligent. One of the best ways to defend their smarts is to look at their language. Cornell University talks about their call diversity, listing 11 unique turkey vocalizations. A truly dumb animal wouldn’t have the need or ability to produce such a complex vocabulary that ranges from soft tree yelps to loud clucks or putts.

    Their conservation success story also gains them intelligence points. At one point, there were only about 30,000 wild turkeys left on the continent, which is less than the populations of some of today’s endangered animals, including African elephants and orangutans. Today, however, more than 7 million wild turkeys inhabit North America.

    Much of this triumph is thanks to the turkey’s ability to adapt, which is evident from reintroduction programs that started in the mid-20th century. According to the NWTF, stockings of 30,000 turkeys at 968 sites resulted in 808 established populations. That’s a ridiculously successful turnaround, aided by the intelligence of humans and wild turkeys alike.

    About the Author: Spencer Neuharth is a freelance writer from Sioux Falls, S.D. To see more of his photography and writing, go to boofcommunications.com.

    SIDEBAR: Can’t Smell a Thing …

    “If turkeys could smell, you’d never kill one.”

    That’s what my brother told me after numerous failures in my first year of chasing toms. Is it true, though? Do turkeys really lack the sense of smell? Well … sort of.

    To understand a turkey’s sense of smell, it’s easier to start with their sense of taste. Turkeys have a very weak palette thanks to their lack of taste buds. While some are present, it’s not like that of a human. Instead, turkeys are limited to the simple tastes, like salty, sweet, acidic and bitter.

    The same can be said for their sense of smell. Smells are interpreted by olfactory lobes in the forepart of the brain. In a turkey, these are very small and underdeveloped, leading biologists to believe that their ability to smell is almost nonexistent. Field observations support this, as studies have been done where mothballs placed near piles of corn didn’t deter the turkeys from feasting.

    So, be thankful for those few taste buds and tiny olfactory lobes, as they’re about the only break a turkey’s anatomy affords us as hunters. — S.N.