Sunday, May 15, 2011

Monarchs Migrate to Ellwood Each Year

Each fall, the western monarch butterfly population migrates southeast from the west side of the Rocky Mountains to various sites along the California coast. The City of Goleta is fortunate to be home to multiple monarch overwintering sites, the largest of which is Ellwood Main Monarch Aggregation Site, located along Devereux Creek on the City owned Ellwood Mesa Sperling Preserve. During the first week of January 2011, when the population tends to peak, over 27,000 monarchs were present at the Ellwood Main site.

In the morning and on cool days, the monarchs hang in large clusters on the eucalyptus trees, and can be seen basking in the sun and flying throughout the grove on warm afternoons. The monarchs are most active during their mating season in late January before they begin their migration northeast to the western Rockies.

In decades past, the Ellwood population peaked at 100,000. As recent as 2005, the monarch population at Ellwood Main was over 54,000. The exact reason for this decline is unknown – theories include habitat destruction, exotic parasite predation and the loss of milkweed (the only food source for monarch caterpillars) due to drought.

The Ellwood monarch overwintering habitat is designated an Environmentally Sensitive Habitat Area (ESHA), and is protected by both the California Coastal Commission and the City of Goleta, which owns and maintains the grove.

In 2007 the City of Goleta developed a docent program to provide Ellwood visitors with on-site educational opportunities. The docents enhance the visitors’ experience by sparking curiosity, helping visitors build observational skills, and providing information about butterfly biology, behaviors and migration. These community volunteers are present at the grove each Saturday and Sunday (weather permitting) from 10:00 a.m. to 3:00 p.m., and lead fieldtrips for school and community groups during the week.

The City is currently working with a consultant who is performing a monarch butterfly inventory and creating a habitat management plan. During the overwintering season, the consulting company conducted multiple counts of the monarchs present in the Ellwood grove and studied their habitat to determine which factors are most important to their survival. The habitat management plan will guide the City in its efforts to protect the monarch population while addressing other local interests, such as the need to protect the surrounding homes from wildfire.

The Ellwood grove is accessible through the Coronado Butterfly Preserve, located at the end of Coronado Drive. From the northbound 101, take the Storke/Glen Annie exit and turn left toward the ocean then turn right onto Hollister. Turn left onto Coronado Drive after approximately one mile. From the southbound 101, take the Hollister exit and continue straight for about one mile. Coronado is the third street on the right.

View Ellwood Main Monarch Aggregation Site in a larger map

This article was originally published in Goleta Magazine.