Keeping Tabs on Turkey Numbers

By Joanie Straub, photographs by David Stonner | March 16, 2015
From Missouri Conservationist: Apr 2015

It’s day three, and Jason Isabelle continues to fight the bitter cold.

This early January morning, snow covers the ground and temperatures are in the single digits. Finally, a flock of turkeys comes into view and meanders over to a pile of cracked corn. Six feet behind the corn is the rocket net that Isabelle and his research crew set up the day before.

When the 18 hens and last year’s young begin to feed, Isabelle presses a button. Three rockets sail through the air, the net following close behind. A cloud of white smoke fills the air and the smell of black powder lingers. Finally, the smoke lifts, and he can see the result. Success! Isabelle netted all 18 hens and their young. Now it’s time to quickly get the turkeys banded and fitted with radio transmitters, then set free to once again roam the countryside. Jason Isabelle is the Missouri Department of Conservation’s statewide turkey biologist. It’s his job to monitor Missouri’s wild turkey population and use this information, along with hunter input, to recommend regulations for the fall and spring turkey hunting seasons.

The rocket-netting of wild turkeys is part of a five-year study he began last year. His team is conducting the research project in northern Missouri in partnership with the University of Missouri, the University of Washington, and the National Wild Turkey Federation (NWTF). In addition to Isabelle, many Conservation Department staff from several divisions are included with the project. Funding for the project comes from the Conservation Department as well as grants from the U.S. Fish and Wildlife Service’s Wildlife Restoration Program and the George Clark Missouri State Chapter of the NWTF.

Rocket Nets, Radios, and Manpower

Rocket-netting involves firing a large net over wild turkeys that are baited into open areas, typically corn or soybean fields.

“Rocket-netting is a very effective method of capturing wild turkeys,” Isabelle said. “A large group of turkeys can be captured with a single shot of the net.”

Once captured, turkeys are banded and fitted with radio transmitters then released at the same location where they were captured. Each transmitter has a unique radio frequency, which allows researchers to track a number of turkeys at the same site.

Transmitters weigh less than 3 ounces and are attached so they don’t affect a turkey’s behavior. Transmitter batteries last for several years, allowing researchers to monitor turkeys for extended periods of time.

“The tracking devices we are using are called VHF (very high frequency) transmitters. Once you fit a turkey with a transmitter, the device emits a signal immediately,” Isabelle said. “Unlike a GPS transmitter that stores data on-board, the transmitters we’re using give a signal that we pick up with a receiver and antenna.”

That’s where manpower comes into play. Conservation Department staff, along with two full time and six seasonal researchers, drive into the area where they captured birds, trying to pick-up a signal. Depending on its movement, the transmitter signal will let the team know if a particular bird is alive or dead. If it’s dead, they will try and locate the bird’s carcass to determine cause of death. Isabelle’s team enters all this information into a database, which his collaborators will use to develop population models.

Monitoring Reproduction and Survival

In addition to tracking movement and mortality, the research project involves collecting reproductive information. The team monitors hens in the spring and summer during the nesting and brood-rearing seasons, which run from early April through the end of July.

“During the nesting period, we track hens a lot more intensively because we want to be able to identify when they start nesting,” Isabelle said. “We generally monitor hens about five times a week during spring and summer.”

Once they locate a hen repeatedly in the same area, Isabelle and his team will know she has started to nest, and they mark the general location of the nesting area.

After hens leave the nesting area for good, the researchers locate the nest to determine how many eggs (clutch size) the hen laid and whether or not the nest was successful. Knowing clutch size and how many poults (young) the hen still has with her at a later date allows researchers to determine poult survival.

According to Isabelle, a typical clutch size is about 10-12 eggs, but only about one in three nests hatches. Of the poults that do hatch, only about four of 10 will survive to be a month old.

“Usually only about 40 percent of turkeys survive their first month of life,” Isabelle said. “Young turkeys can’t fly until they’re about 10 to 14 days old and are very susceptible to cold, wet weather and predators.”

Isabelle’s collaborators at the University of Missouri and University of Washington will use information they gain from the project to develop new population models that will provide biologists with information about Missouri’s wild turkey population. Conservation Department staff will use results to update the state’s wild turkey management plan and guide future turkey management efforts.

A Wildlife Conservation Success

The resurgence of wild turkeys in Missouri and the nation is one of the greatest success stories of wildlife conservation. Each spring and fall, turkey hunters enter the woods with hope of bagging one of the most prized North American game birds. In fact, Missouri is one of the top wild turkey hunting states in the country. But that wasn’t always the case.

Wild turkeys once roamed Missouri in such great numbers that they were common table fare. By the late 1800s, those numbers plummeted from around a quarter million birds to a couple thousand by the early 1950s. Loss of habitat and unregulated hunting were to blame. Missouri closed its turkey-hunting season in 1938.

From the 1950s through 1970s, the Conservation Department focused on restoring this popular game bird. Those efforts included trapping more than 2,600 wild turkeys and releasing them into 142 areas in 87 counties, where they were scarce or nonexistent. Missouri’s environment was perfect for the birds. The populations grew exponentially, with birds establishing new populations in the many areas of good habitat and eventually moving into marginal habitat. Even in northern Missouri, once thought to be unsuitable for wild turkeys, the birds thrived.

Through conservation efforts, wild turkey hunting in Missouri has risen from a harvest of 94 birds in 1960 to more than 53,000 in 2014.

Where Do We Go From Here?

Missouri has a long history of conducting wild turkey research. Past research projects have yielded information on survival, harvest rates, and reproduction, all of which provided the foundation for the management of turkeys. It has been more than a decade since the Conservation Department conducted turkey research. This project will build upon previously conducted research and will maintain the Conservation Department’s tradition of using science-based information in its management program. The results will inform wild turkey management decisions and sustain opportunities for all Missourians to view this majestic bird in the wild.

“The Department conducted a long-term research project in north Missouri in the 1980s. In the 1990s, we shifted gears and studied wild turkeys in the Ozarks,” Isabelle said. “So the most current information we have about demographics of the population is from the Ozarks.”

According to Isabelle, it just made sense to conduct the current research project in northern Missouri, where there has been a noticeable decline in the turkey population, and because data is older and new information is needed.

“Having updated information from the field is important to our wild turkey management program,” Isabelle said. “Our collaborators will use the information to develop population models that will be an important part of how the Conservation Department monitors turkey populations in the future.”

Isabelle points out there have been advances in the development of population models that will help determine how many turkeys are on the landscape, as well as wild turkey survival rates, recruitment, and harvest rates. The Conservation Department is using the best science-based data to help make informed decisions to manage the Show-Me State’s wild turkey population.

Results from year one

During the first year of the wild turkey research project, researchers captured over 260 turkeys —140 jakes (juvenile males) and gobblers (adult males) and about 120 hens (females) — in northern Missouri.

According to Department of Conservation Turkey Biologist Jason Isabelle, preliminary research project results have been interesting. First-year research project results indicate hunters are removing a rather small percentage of male wild turkeys from the landscape during the spring hunting season. Of the adult gobblers that researchers monitored, less than 20 percent were harvested by hunters during the spring turkey season. Hunters shot even fewer jakes, harvesting less than 10 percent of the banded birds.

The additional four years of research that remain will allow researchers to determine how much harvest rates (the percentage of banded birds shot by hunters) vary from year to year.

Researchers also started monitoring hens closely to determine how successfully they nested and reared young.

“Most of the hens that we tracked initiated incubation of a nest during the spring,” Isabelle said. “However, the majority of nesting attempts were not successful, which is not unexpected due to the impacts of nest predators and weather.”

For those hens that were unsuccessful in their first nesting attempt, about half started a second nest. Of the poults that hatched, just under half survived their first month of life. In addition to being susceptible to wet and cold weather, wild turkey poults are a food item for a wide range of birds and mammals, including coyotes, bobcats, foxes, raccoons, hawks, owls, and free-ranging dogs and cats.

As they have done with male wild turkeys, researchers will continue to monitor hens for four more years to determine the amount of variability there is in nest success and survival of poults.

Isabelle encourages any hunter who harvests a banded turkey in Missouri to call the toll-free number engraved on the band. Reporting your harvest will provide important information for the project.

This Issue's Staff

Editor In Chief - Nichole LeClair Terrill
Art Director - Cliff White
Staff Writer/Editor - Bonnie Chasteen
Staff Writer - Heather Feeler
Photographer - Noppadol Paothong
Photographer - David Stonner
Designer - Stephanie Thurber
Circulation - Laura Scheuler