Founded in 1968, ACES runs naturalist-led programming across three valley sites — Hallam Lake, Rock Bottom Ranch, and Catto Center at Toklat — including guided bird walks, free summer naturalist hikes, and winter snowshoe tours.
Select / bi-weekly Tuesday mornings, summer into early fall, alternating Hallam Lake and Rock Bottom Ranch
ACES Hallam Lake Nature Preserve, Aspen (some dates at Rock Bottom Ranch, Basalt)
Beginner-friendlyNo-dropPaidSummer
A roughly three-hour morning walk for birders of all levels, led by veteran naturalist Rebecca Weiss. Discounted for ACES members. Runs select Tuesdays — confirm the date and location before going.
Daily, mid-June through early September (Maroon Bells, Snowmass, Aspen Mountain)
Maroon Bells Visitor Center, Snowmass Mall, and Aspen Mountain (Richmond Ridge)
Beginner-friendlyNo-dropFreeSummer
Free naturalist-guided walks daily in summer — Maroon Lake walks, Snowmass wildflower and Ice Age hikes, and Aspen Mountain walks. Times vary by location; see the ACES schedule.