Snake Signals

Equipped with a transmitter that will enable scientists to track it, one of the smooth green snakes is ready for release into the Lake County Forest Preserve District.

Tracking the Smooth Green Restoration

In preparing to release the smooth green snakes into the Lake County Forest Preserve, the scientists found a promising sign in the prairie grass. Seven egg casings lay clustered together, all empty, their hatchlings dispersed into the landscape.

“The nest reinforces that we’re releasing them in the right place,” says Reintroduction Biologist Allison Sacerdote, Ph.D.

Researchers won’t have to rely on eggshells to track the latest batch of snakes, however. The reptiles have been outfitted with tiny transmitters—about one-hundreth of an ounce—that will enable scientists to track them as they make their way through the grass.

The smooth green snake release—the second to take place this summer—is part of a joint conservation project by Lincoln Park Zoo and the Lake County Forest Preserve District. The vibrant insect-eaters had declined in the region as prairies and marshes were turned into farms and housing developments. The forest preserve district restored habitat in response but found the reptiles weren’t returning on their own. So they started a partnership with population biology experts at the zoo.

Last year snakes from the wild were brought to Lincoln Park Zoo to build a breeding program. A large nest was also rescued from an area slated for development, leaving animal care staff with more than 80 hatchlings to care for. “We were happy to have so many snakes off the bat,” says Curator Diane Mulkerin.

To find the best growing conditions for the young snakes, half were placed in “soft-release” enclosures in the forest preserves while the remainder were reared at the zoo. Little information was available about raising the species, so keepers developed their own care program. An elaborate system of cricket farming was even put into place to ensure the tiny snakes could feed on bite-sized prey.

The snakes grew like the grass they resemble. By summer, the scientists decided a subset were ready for release: 18 snakes would be reintroduced to the forest preserve. The first batch of six went out June 30, dusted with fluorescent powder to enable visual tracking. (The trail went dry beneath the soil—an expected outcome with burrowing snakes.) Six more left the zoo July 13. The rest, also with transmitters, will find wild homes in August.

Not all the snakes entered the wild directly. Three from each group were placed in the shielded enclosures, enabling them to acclimate to the grass, sun, prey and possible predators. But the others made their way right into the wild habitat. The latest batch slid into the grass under the watchful eyes of Sacerdote, Conservation Biologist Joanne Earnhardt, Ph.D., and Lake County Forest Preserve District Wildlife Biologist Gary Glowacki.

What now? Planning will continue for the August release. The researchers will lift the receiver three times a week to track the transmittered snakes as they establish themselves in the wild. As they listen for the signal, the scientists keep an eye out for native snakes at the site as well.

“We’d like to put transmitters on some adults to see how they’re using the site,” says Sacerdote. “Every encounter helps us learn what the species needs to thrive in Lake County.”


by James Seidler