Lincoln Park Zoo and the Lake County (Illinois) Forest Preserve District announced the release Wednesday of 18 smooth green snakes.
The tiny snake's native prairie habitat is disappearing, leading the state to list it as an Illinois Species in Greatest Need of Conservation.
Gary Glowacki of the Lake County Forest Preserve District says pesticides and the conversion of prairie into farmland and residential areas are to blame for the snake's decline.
The zoo's role is to give the snakes a head start. More than half of the snakes hatched at the zoo in 2010 and 2011 will be released at the Lake County preserve.
More snakes will stay at Lincoln Park Zoo where they can be seen on exhibit at the Children's Zoo.
The snakes destined for the prairie will be part of what scientists call a "soft release," meaning they will spend some time getting accustomed to the wild while still being contained in a controlled, managed environment designed to limit predators. The individuals are then more likely to stay local to the forest preserve if they are accustomed to the area.
This group of snakes is the second batch released as part of the recovery program.
The Associated Press contributed to this report.