In August you can  explore the King City Trails with a Toronto Region Conservation Area guide.  Its an opportunity to learn about the creatures who live in the area and the vegetation which thrives there.  The walks are free but you need to register with TRCA.

The walks are on the four (4) Tuesday mornings at 9:30; meet at St. Andrews Presbyterian Church at 13190 Keele St.

For more details see here.