BROOKFIELD — Brookfield Zoo has developed a program for a turtle species that have difficulty surviving in the wild by creating an ideal environment for their re-population of the area, according to zoo officials.
The Chicago Zoological Society (CZS) has teamed up with the Forest Preserve District of DuPage County for a re-population and release program of Blanding's turtles at Brookfield Zoo to increase the local wild population.
Blanding’s turtles are endangered in Illinois and threatened nationwide. CZS, which manages Brookfield Zoo, has created a breeding and release program that includes a new outdoor Blanding’s turtle habitat at the zoo’s Dragonfly Marsh exhibit. The program will allow CZS staff to develop and improve breeding and rearing techniques that will increase the species population and ability to survive on release. In the fall, 12 turtles will be released in DuPage County forest preserves to help improve the wild population.
“This is a key indicator species of the overall health of the area's wetlands,” Bill Zeigler said, senior vice president of collections and animal care for CZS. He also serves on the board of directors for the Turtle Survival Alliance, an organization that works to protect turtles worldwide.
Fostering a sustainable population through breeding is an important step to increase the Blanding’s turtle population, Zeigler added.
Blanding’s turtles in the wild have an approximate 2 percent chance of reaching maturity due to predators such as raccoons and herons. Brookfield Zoo received a group of young Blanding’s turtles from the Forest Preserve District of DuPage County that will be housed at Dragonfly Marsh and will grow in the predator-proof area until ready for release. Typically, turtles that are raised by people before being released into the wild have an even lower survival rate than wild turtles do, but Brookfield Zoo is taking important precautions to condition the turtles for their discharge.
Unlike other rearing programs, the turtles will go through normal seasonal cycles by remaining outdoors all year at a small off-exhibit pond on the zoo’s grounds. This will help prepare them for life in various weather and habitat changes. The space at the zoo replicates the turtles’ natural habitat and will be filled with native plants and logs. The turtles will forage on their own for food sources, such as snails, slugs and small fish. Although food is supplemented, the turtles will hunt for it themselves and not be handled.
“We are proud to work with Brookfield Zoo on this and champion the survival of Blanding’s turtles,” Dan Thompson said, ecologist for the Forest Preserve District of DuPage County, in a news release. “Local wetlands, and the plant and animal ecosystem within them, improve our water quality and our understanding of the world around us.”
In addition to the planned release, Brookfield Zoo has created an off-exhibit breeding space for Blanding’s turtles that will house 30 to 40 female turtles. The turtles there could potentially produce 250 to 300 hatchlings per year. The species is a wetlands turtle and requires a marshy water area as its main habitat; however, females lay eggs in upland areas. The space at the zoo will provide both types of terrain to encourage breeding.
Blanding’s turtles can live up to 85 years old, but do not reach sexual maturity until roughly 13-15 years of age. This slow maturation is also paired with the fact that Blanding’s turtles lay a small clutch of eggs — around 12 to 13 at a time. Other turtle species can lay as many as 60 to 70 eggs at once.
To add to the decreased survival rate, there has been an increase in the number of Blanding’s turtle predators in the area. Another issue affecting Blanding’s turtles is people continue to change and try to control water levels in different areas. Hatchlings require a marshy area with low water, but people alter the natural landscape, which can shrink or eliminate Blanding’s turtle habitats.