Crews clear 900,000 pounds of waste but keep poles for nesting purple martins

Midpeninsula Regional Open Space District completed a large-scale cleanup of about 40 acres added to the Sierra Azul Open Space Preserve, extracting more than 900,000 pounds of human debris, including lead-containing and asbestos-laden materials, and restoring natural drainage. While most abandoned vehicles and structures were removed, old telephone poles were left standing after staff observed purple martins nesting in similar poles on nearby Mount Umunhum.

The western subspecies, Progne subis arboricola, had been considered close to local extinction, but the retained poles provided essential habitat. Midpen then designed hollow wooden poles that mimic natural cavities, which proved effective when birds nested in them in 2022. After debris removal, crews re-graded the terrain, hand-seeded native chaparral and forest, and laid weed-free straw, all aimed at supporting the land’s ecological health and the upcoming Umunhum-to-the-Sea regional trail. Ongoing monitoring of the martin population will continue in partnership with other agencies.