As part of its Habitat Conservation Plan (SBMHCP) San Mateo County Parks is developing a pilot program that will explore grazing as a tool in conserving some of the last remaining mission blue and callippe silver spot butterfly habitat.

Grazing cattle eat invasive brush and tall grass, creating space for native flowering plants like lupine to thrive. These plants, while unpalatable to grazers, are a vital food source for San Bruno Mountain’s endangered butterflies.

In the example photo below, the terrain on the left side of the fence has not been grazed. Notice how the tall grass leaves little room for flowers to grow. The terrain on the right side of the fence has been grazed and wildflowers are flourishing.

Grazing Example

The pilot will introduce cattle to two areas on the mountain, one on the Southeast Ridge and the other on the Northeast Ridge (see map). Over the three-year trial period these areas will be thoroughly monitored and analyzed to determine the viability of grazing as a habitat conservation solution. The pilot program has the added benefit of reducing fire fuel in a dry area prone to wildfires.

Learn more about the history of grazing on San Bruno Mountain and the science behind this project in our full description of the pilot

Progress-to-Date - updated September 5, 2023
  • Grazing Strategy Completed (document attached below)
  • Biological Resources Assessment and Biomass Report completed (documents attached below)
  • Assembled Grazing Technical Advisory Committee (TAC) for quarterly meetings
  • Literature review and consultation with other Bay Area land management agencies
  • Baseline Biological Assessment completed – Nomad Ecology
  • Grassland Productivity Study completed – LD Ford Rangeland Conservation Science
Next Steps
  • Finalize Monitoring Plan
  • Install infrastructure (fencing, water, access improvements)
  • Compose license agreement and solicit vendor
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