Silent Spring: Why Are Turkey Populations Falling?

Silent Spring: Why Are Turkey Populations Falling?

It is nothing short of remarkable, a conservation success story rivaled only by whitetail deer. Once on brink of extirpation from much of their historic range, wild turkeys are now thriving. They are found in all 48 contiguous states, plus Hawaii, Mexico and parts of Canada. Thank conservation-minded hunters for that.

All is not well in the turkey woods, though. Hunters throughout much of the country are reporting fewer gobbles, smaller broods and a steady decline in overall turkey numbers.

There is no better example than Arkansas, where turkey populations have plummeted to just a third of the population from 14 years ago. The state’s spring harvest peaked in 2003, when hunters tagged 20,000 birds. Last season, they killed less than 8,000. New York’s turkey population has fallen from as many as 300,000 birds in 2001 to just 180,000 today. Hunters in parts of Virginia, Pennsylvania, Georgia, Missouri and a host of other traditional turkey hunting states are noticing similar trends.

West Nile
Some hunters wonder if a relatively new disease is to blame. First detected in the United States in 1999, West Nile virus can be deadly to wild birds. Crows and jays in particular are highly vulnerable, with mortality rates of 70% or higher for infected birds. Ruffed grouse have also experienced precipitous declines throughout much of their range, especially in the East. Researchers in Pennsylvania suggested the state’s grouse population may be falling in part due to WNV.

So, what’s the connection? Turkeys and grouse are both galliformes, an order of chicken-like birds that have many of the same physical characteristics. So far, little research has been conducted on the impact of West Nile virus on wild turkeys, but researchers don’t think it is playing a role in turkey population declines. One study conducted in a lab inoculated poults with the disease. None died from WNV.

Hunting Pressure
If disease isn’t a significant factor, what about hunting pressure? Despite falling populations, many states still allow the harvest of hens during fall seasons and generous gobbler limits in the spring. As it turns out, hunting mortality is generally compensatory, not additive. That is, a certain percentage of the population is going to die, whether at the claws of a hawk or bobcat or from a load of #5s, because the habitat can only support a certain number of birds.

A number of studies have shown that while humans are the leading cause of adult wild turkey mortality, regulated and managed hunting is generally not contributing to population declines. State wildlife agencies do adjust season lengths and bag limits to tweak populations, but in most cases, they have little effect on overall turkey numbers.

Based on recent history, it might seem like predators are the obvious culprit. Coyotes in particular are everywhere these days and they are usually the first to get blamed for falling game populations. Research has shown they are playing a major role in low whitetail fawn recruitment rates, but coyotes may not be to blame for declining turkey numbers.

Some studies suggest coyotes may actually benefit turkeys. That may be contrary to everything we’ve been told, but coyotes are not a major adult, nest or poult predator. Instead, they can actually reduce populations of raccoons, possums and foxes, which are significant nest and poult predators.

What’s more, we’ve been attempting to control or eradicate coyotes, raccoons and other egg eaters for decades to no avail. Coyotes are as abundant as they have ever been. And in some regions, turkeys and predators are both thriving where they share the same habitat.

So what really matters? Biologists have learned that weather extremes on either end of the spectrum can devastate an entire spring hatch. Hot, dry weather during the critical stages of a poult’s life can be just as lethal as extended periods of cool, wet weather.

Texas’ turkey population, for instance, plummeted after several years of severe drought during the early 2010s. That’s because dry weather inhibits spring green-up. Without an abundance of tender, green plants, there is a severe shortage of insects, the primary food of baby turkeys.

On the other hand, cool, wet weather can also decimate poults. Vermont experienced one of the lowest poult recruitments on record after an extended period of cool, rainy weather in June and July in 2017. Arkansas also experienced a string of cool, wet springs. Young turkeys (and other birds) are especially prone to pneumonia during the first few weeks of their life. Two or three years of harsh weather at the wrong time of the year can depress turkey populations.

Less Habitat
Although scientists are still looking for answers, a growing number think long-term declines may be directly linked to changes in suitable habitat. The slow, steady march of housing developments, office complexes and strip malls is eating away an estimated 6,000 acres of open space per day, according to the U.S. Forest Service. On top of that, aging forests, a decline in early-successional habitat and the increase in neatly-manicured fescue fields has led to lower nest success and poult survival.

Young turkeys in particular have specific needs. Their survival depends on two things: Dodging predators and finding adequate food, which, in the earliest stages of their life, is insects. The best place to find bugs is in open fields, mixed-habitat forest edges and forest openings with herbaceous plant growth.

But those poults also need overhead cover, or at least quick access to that cover. Hawks and owls take lots of young turkeys, as well as bobcats and foxes. Without suitable brood habitat, poults are easy targets for a variety of predators.

That habitat is declining, including on our national forests. The acreage of timber harvested on federal land has fallen dramatically in the last 30 years, thanks mostly to environmentalists. The mere mention of cutting a tree in a national forest is often met with a lawsuit, even though timber harvest ultimately results in outstanding wildlife habitat. Even private landowners are cutting fewer trees.

Those that do often replace mast-bearing hardwoods with fast-growing pines. There were about a half-million acres of planted pines in Arkansas in 1980. There are an estimated 2.5 million acres today. Similar trends are taking place throughout the Southeast.

While young stands of planted pines can be outstanding nesting and brood-rearing habitat, they age out. What starts as an impenetrable jungle of blackberry thickets, native grasses and volunteer trees within the planted pines evolves into a monoculture of loblolly pine trees in a decade or so. Nesting cover and bugging habitat eventually disappear, leaving behind a forest floor devoid of cover.

All of those factors—the loss of suitable habitat, a few springs of unfavorable weather and increased predation—may be merging to put a 1-2-3 punch on turkeys in some regions.

The good news is that the downward trend in turkey numbers seems to be leveling off in some states. Even better, an increasing number of landowners, conservation groups and state and federal agencies are working to reverse the trend by improving habitat at every opportunity. The federal government even provides technical assistance and funding for qualified landowners. And some environmental groups are finally realizing that cutting trees can be good for a variety of wildlife. Of all the conservation success stories, that may be the most remarkable of them all.

Feature image via John Hafner.

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