Join Liam O'Brien, lepidopterist, in search of the San Bruno Elfin, one of three endangered butterflies on San Bruno Mountain and also one of its most elusive. The group will spend time at the summit and then walk west along the Ridge Trail. Bring water and snack or lunch. Dress for varied weather.

Limited to 20 participants - you MUST SIGN UP IN ADVANCE or contact us at sanbruno [at] mountainwatch.org, or call the office at 415-467-6631.