CHICAGO (AP) -- Officials are collecting the Chicago area’s remaining rattlesnakes as part of an emergency species survival effort.

The U.S. Fish and Wildlife Service and Illinois Department of Natural Resources are working to place the eastern massasauga rattlesnakes in a breeding program at the Lincoln Park Zoo .

The massasauga are on Illinois’ endangered species list. They were once common to the Chicago region but now can only be found in one area wetland.

Lincoln Park Zoo biologist Joanne Earnhardt says the 2-foot-long snakes have non-lethal venom and are shy and quiet.

Project manager Joe Kath of the state Natural Resources Department says officials had a choice between watching the snakes disappear or taking action to build their population.