Loyola professor studies ornate box turtles in Will, Grundy counties

When Joseph Milanovich, Ph.D., of Loyola University Chicago, embarked on a two-year study of a threatened species of turtle in Will and Grundy counties, he knew the best way to find them.

Bring in some turtle dogs.

“This gentleman from North Carolina has trained these dogs to find turtles, much like dogs find ducks or track bears,” said Milanovich, an assistant professor in the Loyola biology department. “So we hired him for a few days to locate these turtles for us.”

Milanovich received a grant from the Illinois Department of Natural Resources Wildlife Preservation Fund titled “Demography, Stress, and Diet of the Ornate Box Turtle (Terrapene oranta) in the Sand Hills of Will and Grundy Counties, Illinois.”

With it, Milanovich “investigated the ecology of a threatened terrestrial turtle species historically found in large numbers in the prairies of Will and Grundy Counties,” a Loyola news release stated.

He worked at two sites: the Wilmington Shrub Prairie and Goose Lake Prairie in Morris. The Illinois Department of Natural Resources owns both prairies.

The project focused on understanding the turtles’ habitats, hibernation sites, stress levels, physiology and diet, with the goal of better management strategies for the turtle species and area prairies as a whole, Milanovich said.

The investigation, Milanovich said, ended in December. He is now processing the data. Milanovich said his findings are significant because even one threatened species in the areas of Will and Grundy counties can upset the entire prairie ecosystem.

That, of course, includes the ornate box turtle, a prairie-adapted species, he said.

“All species should exist where they should exist,” Milanovich said.

The first thing Milanovich did was survey the turtles. That confirmed their threat status as well as how robust the population status was in those two sites. A comparative study, Milanovich said, seemed to indicate fewer turtles in Will and Grundy counties than in other areas in Illinois, he added.

One red flag, he said, was the age of the turtles. Most of the turtles he found were more than 10 years old, which is not terribly old for turtles, as they can live for decades.

What was unknown, he said, is the age turtles stop mating. An older population of turtles might indicate fewer births.

Age is determined by looking at the panels on the turtle’s shell, which resemble floor tiles, Milanovich said. Each tile has rings and each ring represents one year of growth.

“You get a good estimation of age by counting all the rings,” Milanovich said.

In his investigation, Milanovich encountered more male than female turtles, which might be climate-related, he said. More males are born in warmer temperatures and “fractions of degrees” can determine sex, he said.

“It might [also] be that the female is more susceptible to predation,” Milanovich said.

Milanovich then added radio transmitters resembling little antennas to 26 turtles (one turtle later died of natural causes, Milanovich said) and tracked them for 12 months through the seasons.

The findings

Ornate box turtles hibernate several hundred days of the year, Milanovich said, and hibernate deeply enough to withstand temperatures 0.5 degrees above freezing. They select hibernation sites close to each other, tend to return to the same sites each year and emerge in April, just in time to mate in May. The eggs hatch in June or July, he said.

By studying blood samples and nail clippings, Milanovich learned that the turtles ate a wide variety of plants, even seeking out sodium-rich plants if they felt the need for more sodium in their diets. They also enjoyed meals of earthworms, slugs and beetles.

“Typically box turtles are generalists,” Milanovich said. “They eat more or less what’s in front of them.”

Milanovich determined how the turtles coped with stress through measuring certain hormone levels in their white blood cells. One threat Milanovich expected to see and did not was disease – the ranavirus in particular, a nasty virus seen in other turtles for which no vaccination exists.

“It’s very easily spread during mating seasons from secretions in the eyes and mouth,” Milanovich said.

Overall, Milanovich feels that reptiles and amphibians are understudied, which leaves huge knowledge gaps in understanding the changing environment.

Because they are small and less mobile than other species, Milanovich said, reptiles and amphibians provide valuable ecological information.

“Birds can fly away from climate changes,” Milanovich said. “Reptiles and amphibians have to deal with whatever happens to it.”