City of San Leandro and Wildlife Biologists Open Elevated Boardwalk and Nectar Sanctuary at Shoreline Monarch Overwintering Grove

Shoreline stewards with the City of San Leandro Recreation and Parks Department and entomologists from the Xerces Society for Invertebrate Conservation inaugurated a 520-foot elevated permeable timber observation boardwalk and a two-acre native winter-nectar pollinator sanctuary on Saturday evening along the Monarch Bay shoreline grove at 13800 Monarch Bay Drive near the San Leandro Marina. Timed for the late-October arrival of migrating Western Monarch butterflies (Danaus plexippus) from across the Sierra foothills and Great Basin, the protected microclimate grove consistently hosts one of Alameda County's largest overwintering butterfly aggregations between October and February.

Because foot traffic beneath the roosting trees previously compacted fragile feeder roots and disturbed low-hanging butterfly clusters on cool mornings, crews constructed a screw-pile-supported recycled-redwood boardwalk raised eighteen inches above the forest floor. Three cantilevered viewing alcoves with angled spotting-scope rests and bilingual English, Spanish, and Chinese interpretive displays allow school classes and photographers to observe the shimmering amber-and-black clusters thirty feet overhead without stepping into the drip-line sanctuary.

To shield the roosting canopy from winter Bay gales while replacing senescent limbs, arborists planted forty-five wind-buffering Monterey cypress and coast live oak saplings around the perimeter. Volunteers also established 1,800 winter-flowering native coyote brush, narrow-leaf milkweed, and seaside daisy shrubs that provide critical nectar lipid reserves on sunny winter afternoons.

The $315,000 monarch habitat project was funded through a California Wildlife Conservation Board Monarch Butterfly and Pollinator Rescue Program grant and City of San Leandro shoreline funds. Visitors can check Saturday docent tour hours on the City of San Leandro Recreation & Parks Portal.