The Monarch Butterfly Sanctuary in Pacific Grove is a small area of eucaplyptus trees and nectar plants that provides an overwintering location for western monarchs. During this time, typically from late October or November until February, thousands of monarch butterflies remain in the grove, residing in the central California coast's cooler temperatures until warming spring conditions lead the monarchs to migrate toward Canada and as far east as the Rockies.
Monarch butterflies, unable to survive in freezing temperatures, leave their mountainous feeding and birthing locations in the fall. Up to four generations of butterflies live over the course of a year, meaning that the butterflies who return to California coast annually are several generations removed from the previous year's overwintering population.
During winter monarchs typically cling to the eucalyptus and pine trees inside the grove as well as in similar areas up and down the central California coastline. They remain dormant on cooler days, but they fly to find food on warmer days.
Inside the sanctuary in Pacific Grove, populations of butterflies cling to eucalyptus branches high up in the trees. The subdued colors of their closed wings make them somewhat hard to spot at first. When you finally see them, you'll begin to see hundreds of them in many of the surrounding trees and on the ground, both on and off of the path.
Binoculars may be helpful in allowing visitors to see the butterflies at their high perches. The Pacific Grove Museum of Natural History normally has docents at the grove daily from noon until 3 p.m. during the overwintering season, and they can answer questions about the butterflies.
The grove also contains a variety of nectar plants that provide food for butterflies and create a colorful and scenic environment for those walking the footpath through the sanctuary.
The best time to see the butterflies is from noon until 2 p.m. during the warmest hours of the day when they are most active.
Visitors are permitted in the grove from sunrise to sunset daily. There is no admission fee. Parking is available for free along the streets near the grove. There is no water on site, though there is an outhouse located at the southern end of the trail.