Research Examines Overlap Between Predation and Nesting Habitat

One of the primary areas of concern among hunters, landowners and many others who care deeply about the wild turkey is the effect predators have on the bird’s presence on the landscape.

While many predators no doubt eat wild turkeys and ransack their nests, the birds have co-evolved with predators and are experts at evading them (hunters know this all too well), especially when the bird’s habitat needs are being met.

This begs the question, though, what is impacting the wild turkey population to a higher degree: increased predators or lack of sufficient habitat to avoid becoming prey? Or both?

This question is at the heart of a comprehensive wild turkey research study in southeastern Iowa – where there is no shortage of predators and the five-year poult-to-hen ratio averages 1.9, indicating the population is in decline. The ongoing project is being conducted by the Iowa Department of Natural Resources, Luther College and the USDA Animal and Plant Health Inspection Service. The NWTF Iowa State Chapter is providing funding for the project, and the NWTF also invested in this project as part of its 2023 investment in wild turkey research.

IDNR initiated the 10-year research project two years ago in the southeastern part of the Hawkeye State to investigate the factors driving declines in poult production and hen survival, as well as update and improve the understanding of other wild turkey ecology data, including how habitat quality correlates to the rate of nest predation, female demographic rates, disease prevalence, resource selection, movement behavior and more.

“Much of the wild turkey population dynamics information in Iowa is outdated,” said John Burk, NWTF district biologist for Iowa, Missouri and Illinois. “There is no doubt a decline, and there is also no doubt that predation plays a major role in it. We have always known of the importance of nesting and brood rearing habitat and have a decent handle on what it should generally look like. However, our understanding of how these habitats need to be specifically juxtaposed on the landscape to reduce predation rates is something different that many ongoing turkey studies are taking a closer look at. Our volunteers in Iowa are proud to support our efforts to better understand what is impacting this resource and what we can do to conserve it.”

Since the project began, IDNR staff have marked 161 female wild turkeys with VHF (Very High Frequency)-GPS transmitters. In 2022, the research team found that the overall nest success rate was only 11%, indicating a 10% decrease from previous studies.

“It’s important to note that we are in the infancy of our study and it is unclear how the one year of data will fit into the long-term picture, but of these nests, more than 80% likely failed due to predation,” said Dan Kaminski, IDNR wildlife research biologist and principal investigator of the project. “Overall female survival was 55%, which similarly indicated a decrease from previous studies in Iowa and an area of concern, although there are likely many interacting causes for this decline, including disease, predation and other factors.”

Kaminski noted that the cause for an increase in predation and to what extent certain mammalian species contribute to wild turkey nest and female predation is also unknown. The IDNR is examining if poor nesting habitat is the culprit.

“The relationship between nest success and predation in highly agricultural regions of the Midwest is poorly understood,” Kaminski said. “Nest predation has been shown to vary by environmental factors, including forest cover and weather variables, yet much of the focus on nest success is centered on predation behavior, which may lead to biased inferences about production declines. We need to better understand the relationship between habitat and predation to improve management efforts and avoid biases.”

Kaminski noted that past wild turkey studies examining the predation-habitat relationship used a qualitative approach – anecdotal data lacking the rigors of quantifiable science – to correlate species with nest predation rates.

This new study is taking a quantitative approach, gathering and evaluating data that can be used to put specific numbers behind the predation-habitat relationship and ultimately paint a clearer picture.

For instance, the VHF-GPS transmitters attached to hens will provide valuable data that will allow the team to pinpoint when and in what habitat a hen is nesting, and they will be able to see if a nest fails from her movement data in near real time.

If the nest fails due to predation, using non-invasive genetic techniques, Kaminski and the research team will be able to identify what mammalian species are predating nests by collecting saliva from the ransacked eggs and predated carcasses. This information, coupled with the habitat and movement data, could be able to fill in the gaps in the current research. 

Over the next seven years, the project will continue marking wild turkeys, examining the cause of nest failure, measuring the habitat and identifying which mammalian species are predating nests. Analyzing this combined information will provide a better understanding of what habitat is optimal for wild turkeys to evade nest predators and could guide future habitat management efforts.  

In addition, the project will also bring other important information up to date, including adult female survival rates, nesting and nest success rates, poult survival rates, clutch sizes, cause-specific mortality rates for nests, prevalence rates for avian diseases in adult female wild turkeys and updating wild turkey demographic data.

“Using these data, wildlife managers will be able to provide science-based recommendations on the management of wild turkeys and their habitats to inform the development of appropriate policy and management actions, with the ultimate goal of directing conservation resources towards efforts capable of improving wild turkeys and other populations,” Kaminski said. “While this work is happening in southeastern Iowa, its findings can have applications beyond state lines and can help conserve this awesome resource far into the future.”

This endeavor is one of 10 new research projects the NWTF is funding as part of its 2023 investment in wild turkey research. Stay tuned to NWTF.org, as the NWTF highlights the importance of all these projects and how they ensure a healthy future for the resource.