Winding west and north along the bluff above the Chicago River, the bike path runs through the Forest Preserve known as Bunker Hill Savanna and Sidney Yates Flatwoods . Bounded by Caldwell, Devon and the North Branch of the Chicago River, the site is approximately 100 acres and lies within the Chicago city limits. It encompasses a mosaic of open savanna, oak woodland, and flatwoods.
Heading west from Devon and Caldwell, the bike path skirts the flatwoods, an unusual community that has an underlying stratum of clay, causing it to hold water for long periods of time in the wet season. The presence of this rare community helped earn the site its designation as an Illinois Natural Areas Inventory site. The flatwoods canopy is dominated by tall, straight Pin Oaks, here at the northern extent of their range. In the fall, the rare Spicebush shrub brightens the woods as its leaves turn a lovely lemon yellow.
Turning north, the path winds through oak woodlands before coming to the open savanna. Native wildflowers such as blazing star, obedient plant, mountain mint, prairie sundrops and native grasses such as big bluestem, northern dropseed, Indian grass grace the savanna. Many young pin oaks and swamp white oaks dot the opening. Song sparrows sing from the tops of bushes. An unusual dragonfly, one of the rainpool gliders, was sighted for the first time in 1990, cruising in large numbers over the savanna flora.Unique communities such as these provide critical habitat for birds, butterflies, frogs and other animals that otherwise could not survive.