The Conservation Department is leading an evening hike at the Mill Pond Conservation Area on Wednesday from 5:30 to 7 p.m. The conservation area is 150 acres of forest, shrub, and wetlands surrounding the Mill Pond Reservoir in the eastern part of town near the Wilmington and Woburn lines. Participants will walk along the scenic trails that surround the reservoir, one of the town’s two drinking water supplies. Organizers hope that during the walk, the group will be able to see or hear native wildlife species that are most active at dawn and dusk, including deer, squirrels, and raccoons, and those that are most active at night, such as foxes, opossums, and owls. The event is free and open to all, but those participating are asked to register in advance. Parking is available at the water treatment plant on Winter Street. Participants are encouraged to bring binoculars and field guides if they can, and a flashlight. To register or for more information, call the Conservation Department at 781-270-1655.