At Natural Bridges State Park, The monarch grove contains eucalyptus trees which are located in a gently sloping canyon, providing the Monarch needed shelter from the wind.
The monarchs typically begin arriving in mid-October and have left by mid-February The park's Monarch Grove provides a temporary home for up to 100,000 Monarchs. From late fall into winter, the Monarchs form a "city in the trees."
Natural Bridges State Park's Monarch Grove has been declared a Natural Preserve, thus protecting these butterflies and their winter habitat from human encroachment or harm. This is the only State Monarch Preserve in California