Monitoring Illinois Turkey Population is a Public-Private Partnership

Anyone who spends a lot of time outdoors knows that rules and regulations may differ widely across state lines, and that wildlife, such as wild turkeys, are oblivious to political boundaries. The same is true for the ecological drivers that influence turkey populations to increase or decrease. Over the last 15 years or so, much of the eastern United States has experienced declines in turkey populations, as indicated by harvest data trends and multiple scientific surveys. To get a better grasp of what is going on at multi-state and regional scales, a group of state turkey biologists (known as the National Wildlife Turkey Federation (NWTF) Technical Committee) and researchers decided it was time to standardize some forms of data collection so trends could be more accurately compared amongst states.

Monitoring Turkey Reproductive Success

Many factors influence wild turkey abundance, but over the years reproduction has been identified as the most important. The growth or decline of a population in an area hinges on how many eggs can eventually become adult turkeys. One of the most important tools that wildlife managers rely on to monitor reproductive success each year are wild turkey brood surveys.

Many states, Illinois included, have been conducting these surveys in some fashion for decades. The surveys have created valuable datasets for identifying trends within a state. Most states differ in how they collect or analyze these data, however. For example, Illinois has always collected data during June, July and August while some states only log observations in July and August.

Some states, such as Kansas, ask rural mail carriers to collect data while other states rely on their agency staff to report sightings. Those approaches can yield high quality data because measures of effort (birds sighted per mile, hour, etc.) can often be collected or because survey participants have expertise in animal identification. A tradeoff with those focused approaches is less data can be collected overall, resulting in smaller sample sizes.

In Illinois, anyone—state, federal, and local conservation professionals, as well as the general public—may participate in the brood surveys and report their turkey sightings (read Changes Ahead for the 2023 IDNR Turkey Brood Surveys). While there might be some inherent error with this approach, it certainly results in a large number of observations which can be powerful for detecting trends at multiple scales.

A Standardized System Develops

Several years ago, at a multi-state meeting, managers and researchers were attempting to compare their brood survey data sets and realized that by collecting or analyzing data with different methods they were comparing apples and oranges. Few conclusions could be drawn across state lines when methodology was so different. Representatives from the southeastern states at that meeting decided it was time to develop a standardized protocol. Soon, representatives from states all over the country were involved in the collaboration and a formal protocol was developed by the member states of the NWTF Technical Committee.

Data Sharing Across State Lines

With just a few key changes and attention to detail, approximately 30 states now share their data in a way that can be analyzed at state, regional and national scales. For example, adjusting the Illinois survey technique entailed merely adding a question for observations of male turkeys and making it clearer that reports were needed of observations of female with and without young. This ensured that the Illinois Department of Natural Resources (IDNR) would be able to compare data to their historic dataset as well as the national partnership.

Illinois Data and the National Dataset

What does Illinois’ data show since we started collaborating in this effort and how do they compare to other states? The primary metric monitored with these surveys are the number of young compared to the number of adult females, called the poult-per-hen ratio (PPH). In Illinois, this number has fluctuated year to year, but almost always stayed above two poults for every hen (PPH). It was not uncommon for results to be as high as 2.5 PPH for many years. However, around 2016 a downward trend started and generally continued for a few years, bottoming out in 2020 with an all-time low of 1.42 PPH. Fortunately, each year since 2020 has produced higher numbers. In fact, 2023 was the highest number reported since 2015 with 2.27 PPH.

The first year collaborating with the multi-state effort was 2019, so five years of data is available using the standardized methodology. Because IDNR did not need to make many changes to the methodology when making the transition, these data tell the same tale as the historical method; very low numbers in 2019 and 2020 followed by steadily increasing numbers through 2023. The benefit of the new protocol is the comparison amongst other states and additional metrics.

In five years of participation, Illinois has been right in the middle of the pack for wild turkey reproductive success. This is a relatively good position to be in considering there are some states (Maine, South Dakota, Wyoming) where reproductive success has been very high and populations seem to be growing. While there are other states in the southeast where reproductive success has been low for many consecutive years and populations have clearly declined. In Illinois, our statewide population has remained relatively stable.

Another benefit of the collaborative analysis is that we now have multiple other ways to measure reproductive success and survival in addition to PPH. Poults-per-hen will continue to be the primary metric we follow as it gives an indication of overall productivity. Poults-per-brood can be used an indication of poult survival within a season. One more metric is the ‘Percentage of Hens Observed with Poults’ which can be used to estimate amount of nesting success hens are having. Finally, we also use the ‘Male to Female Ratio’ to monitor the carryover of gobblers from the previous spring turkey hunting season. All these metrics have generally followed a similar trend; they were lowest in 2019 and have steadily improved each year, with PPH seeing the steepest increase.

You Can Help Monitor Wild Turkey Populations

As with any statistical analysis, the more data you can collect, the more concise the inferences that can be made. We can’t build a larger sample size without volunteer citizen scientists so please help us by reporting your turkey sightings. Anyone and everyone can participate in the IDNR Wild Turkey Survey.

Participating is now even easier than ever because of an electronic survey format that allows participants to log observations from their mobile phone or on the IDNR website. For those hesitant to try the electronic method, postcards can be mailed for participants to log their observations. Several participants have simply emailed the details of every turkey sighting they make, which is also perfectly acceptable.

Long story short is that IDNR needs all the help we can get with this effort.

If you would like to participate in the Wild Turkey Survey, check out the IDNR website here. Email the author at luke.garver@illinois.gov with any questions, or to request to be mailed postcards.

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Luke Garver is the Wild Turkey Project Manager with the Illinois Department of Natural Resources, Division of Wildlife Resources.