Everyone knows the wild turkey is a prey species.
However, few folks realize the extent to which predation has made the bird what it is.
Predation by the Numbers
In a study of turkey productivity, several colleagues and I monitored 248 nests of 202 hens. We found that the most serious effects of predation are nest destruction and poult losses.
About 50 percent of nests fell to predators. Major nest predators included raccoons and skunks, but snakes, opossums and gray foxes also took eggs.
More than 70 percent of poults fell to predators during the two-week ground-roosting period after hatching. Major predators of young poults were raccoons, crows and raptors.
At the time of hatching, poults have 1-in-8 odds that they’ll live to six months. The mean life expectancy of 6-month-old turkey is 1.5 additional years.
The turnover time of a turkey population is only about 3.8 years, which means only a small fraction of a turkey population lives longer than four years. About one-third of unhunted turkey populations and one-half of hunted populations die each year.
Even in refuges, 4-year-old turkeys are not common, 5-year-olds are uncommon and 6-year-olds are rare. In refuges, gobblers typically outnumber hens because of predation on hens when they’re nesting and roosting on the ground with their poults. The oldest documented wild turkey was only 12, and few 10-year old turkeys have been recorded.
After hatching, poults experience a bonding process with the brood hen called social imprinting. After four days with the hen, bonding is irreversible, and the poults follow the hen. Four-day old poults cannot recognize predators, but nature has instilled in them an instinct to be cautious of all other objects — especially large objects that move.
Because of high losses to ground-roosting broods, poults learn to fly early to roost in trees. They undergo a wing molt while still in the egg and hatch with their flight feathers partially developed. By six days, when they chase an insect and fall behind the brood, poults flap their wings when catching up. By Day 8, when poults fall behind, they can fly through the air farther than they can jump. By then, it might be said they’re flying.
By 10 days, poults can fly like drunken butterflies when a predator strikes, and by 15 days, poults can roost on low limbs of a tree beside the hen. After poults start flying up to roost, the predation rate falls precipitously.
The Hen’s Warnings
The hen is alert for predators and has a vocabulary of warning calls to control her young brood when danger threatens. The poults understand warning calls by instinct.
When the brood hen spots a stalking predator, she issues a call that freezes her flightless poults in place. The freezing reflex is amazing. A 2-day old poult in the frozen posture can be handled by a human and won’t attempt to escape. If placed back on the ground upside down, the poult will merely turn over and lie there.
The hen uses another call when she spots a predatory bird, and when poults hear that call, they scramble for cover.
Grown turkeys have warning calls, too. A good example is a vocalization issued by a turkey in a scattered flock when it spots a stalking predator. I discovered this call in the late 1970s, when I was hunting in fall. I had scattered a family flock at roosting time. I knew the turkeys would not call unless they were stimulated, so I yelped. I was answered immediately by a very unturkey-like sound. I yelped again and was answered by the same sound. I moved forward and flushed a turkey out of a tree.
I returned the next morning. When I yelped before the turkeys began calling, I was answered the same sound I had heard the previous evening. Fifteen minutes later, the turkeys started yelping, and a jake flew down almost in my lap.
Since then, I’ve heard and recorded that call many times when turkeys were calling and one detected me. I named it the hush call because it warns other turkeys to stop calling.
Turkeys instinctively identify some predators by appearance. For example, a turkey recognizes a predatory bird on sight, and incubating hens will chase snakes away from their nests.
However, the most important cue for predator recognition is predatory behavior. A non-predator pays little attention to turkeys and does not move intentionally toward them.
Conversely, a stalking predator looks intently at its prey with both eyes and moves slowly toward it. A turkey recognizes that as predatory behavior and evades any animal acting that way. That’s how turkeys learn to avoid new types of predators — including humans.
However, turkeys will become rather unwary when experiencing repeated benign human presence, which underscores the role of predatory behavior in predator recognition. When humans act in a non-predatory manner, turkeys tend to be unwary.
Turkeys offset high predation by being extremely wary and highly productive. Hens nest in their first year, lay 10 to 12 eggs and re-nest when a nest is destroyed.
Young and older hens lay almost the same number of eggs, and they lay about the same number eggs in the second nest if their first nest is destroyed.
Hen turkeys use several major behavioral adaptations to avoid nest predation, including:
▶ Selecting a well-hidden nest site.
▶ Visiting the nest to lay at midday, when they won’t leave a scent trail for nocturnal predators,
▶ Covering the nest with leaves before leaving during the laying period.
▶ Minimizing activity near the nest.
▶ Wearing cryptic plumage.
▶ Remaining on the nest when predators approach.
▶ Sometimes flying to and from the nest.
▶ Not defecating on or near the nest.
▶ Leaving the nest with the brood as soon as possible after hatching so the smelly eggshells won’t attract predators.
Because predation is so high, the average life span of a turkey is brief. Some turkey hunters think they’ve hunted the same old gobbler for several successive years, and sometimes that happens. But usually, when an old gobbler dies, another one takes up residence at the same place, because the elements that initially attracted a turkey make it attractive to others.
In the short run, it’s difficult for hunters to think of predators as desirable.
However, predation has been the driving force behind the evolution of the wary and productive wild turkey.