Birds of interest at Onion Mountain Park include:

• Winter Wren
• Blue-headed Vireo
• Black-throated Green Warbler
• Black-throated Blue Warbler

This town-owned park consists of 190 acres of wooded, rocky mountainside. Trails here are relatively easy on the flat but significantly more difficult on the hillside. The ground can be very wet after rains. Onion Mountain Park is accessed on the west side of West Mountain Rd. just south of Shingle Mill Road. Visitors will find a good size parking lot.

The yellow and blue trails at the base of the mountain run north/ south over gently rolling, formerly agricultural land. Most trees in this area are 40-50 years old and are a mixture of hardwoods and evergreens, including white pine, hemlock, oak, and beech. Part way up the mountain are several small wetlands and seasonal brooks.

The 100 acres on the northern end of the mountain’s east slope were cut to open the area for improved wildlife habitat and hiking trails. The orange trail winds diagonally up the mountain on old logging roads. The trees here are 80-120 years old, mostly oak and hemlock, with small hemlock, low growing viburnum, witch hazel, and sugar maple in the understory. The red trail in this area is used to check boundaries and is not well cleared. The white trail at the north end of the property joins the orange and red trails.

The AllTrails website has a map and description of two hikes at Onion Mountain Park, a 4.1 mile hike on the Orange-Blue Trail and a 1.7 mile loop.