How turkey hunters may cause turkey hens to have more daughters

Caption

Firearms Training Systems Inc. instructor Mike Murphy demonstrates the company’s virtual reality turkey hunter system at the factory in Suwanee, Ga., on July 17, 1995.

Credit: John Bazemore/AP

When it comes to turkeys, hunters and turkey hens are after the same thing: big, bold, burly tom turkeys.

Now a study from UGA’s Warnell School of Forestry lays out how hunters’ quest for trophy birds may lead to more turkey daughters. 

For three years, researchers collected eggshells from four sites in three Southern states, at first to learn more about how many males were represented in a clutch of turkey eggs. Ph.D. candidate Erin Ulrey said the team expected to find the young (called poults) to have been about 50% male and 50% female.

But at some of the sites, Ulrey — who's one of the authors of the study that first appeared in the Journal of Avian Biology — said they saw something different. Something she said was, well, weird. 

"Why are the majority female?" Ulrey remembers asking herself. 

When Ulrey broke down the numbers, the poults were about 62% female. The next question was "Why?"

First, the imbalance was present at some but not all of the survey sites. What was different about those? Ulrey and her colleagues ran through some possibilities.

"If there aren't a lot of food resources available during some years, if maybe it is colder out during the winter," she said. 

None of that panned out. But something else did. 

"It just kind of seemed to come out that every time it was an unhunted or a hunted population."

At the one survey area with no hunting at all, near the Savannah River Site, Ulrey said tom turkeys thrive. 

"Male survival is much higher,” she said. “I mean it's higher than females’ survival."

It was where there were spring hunters that eggs hatched more female young. The upside: more females could mean more nests, more eggs and better numerical odds against hunting. But over time it could also mean not only fewer of the most desirable toms for hens to mate with, but it could also mean fewer males altogether. 

For hens, that’s the downside. 

"Are they going to choose to maybe mate with a male that they don't want to?" Ulrey asked. "Are they going to be forced to maybe travel further to find males?"

As to how this shift occurs, Ulrey said that’s an open question. Corticoid steroids are hormones animals (including humans) release during extreme stress. Maybe they are responsible for the hens shifting the sex ratio of their young, Ulrey said. 

That raises another set of questions for her.

"And then there's, you know, are they making a choice?" she said. "And how do they know?"

The answers are yet unknown.