Bryan BeilkeCalifornia is the only state in the nation that is home to what Cal Poly entomology professor emeritus Kingston Leong refers to as a “national treasure.”
This phenomenon, the Pismo Beach Monarch Butterfly Grove, has been known to support up to 200,000 butterflies.
This particular colony is one of the largest in the nation, hosting an average of 25,000 butterflies per year over the last five years. In fact, most years Pismo Beach has had the largest collection of monarch butterflies in the United States.
Pismo Beach is not the only area along the California coast that is home to the butterflies though; Montaña de Oro, Los Osos and Morro Bay are other groves where the butterflies migrate.
Luckily, what was once kept secret by a select few in the 1940s is now open to all those who wish to gaze upon the thousands of beautiful orange and black monarch butterflies that flock to the grove each year. Gary Espiau, a volunteer docent for the grove, said that as time went on people realized the “importance of being knowledgeable in order to protect the species.”
The monarchs that visit Pismo Beach are not ordinary butterflies; they have a life span of six months, as opposed to common monarchs who live only six weeks.
Though scientists aren’t sure why the monarchs consistently return to the same spots along the Central Coast and Mexico, some speculate that the insects are equipped with genetic homing systems that lead them to their winter destination.
Leong said he believes that past studies which determined that there are two separate populations of butterflies (one that migrates to the California Coast after feeding on milkweed west of the Rocky Mountains, and one that migrates to Mexico after feeding on milkweed east of the Rocky Mountains) are actually wrong.
“I think there is a link,” he said. “We have found that in the spring when they disperse we find them going over the Rocky Mountains.”
Espiau said the butterflies start to arrive around October and come to the grove to avoid freezing to death. “It’s the only insect that migrates to avoid freezing,” he said. “They’re tropical insects and can’t stand cold temperatures for long periods of time so they choose a place like this.”
Espiau describes the grove as an “oasis” and a “sanctuary” for three main reasons. First, “the butterflies are looking for a place that’s got moisture to prevent dehydrating and the eucalyptus trees also provide wind protection,” he explained. “There’s also a meadow and stream where the fog will come in so they can get a drink of dew in the morning. A humid climate is also a must for the insects because they go into a dormant state called diapauses, which is like semi-hibernation.”
Visitors from all over the Central Coast come to view the insects and their unique style of shielding themselves from rain and keeping warm. The monarchs form dense clusters with each one hanging with its wing over the one below it to create a shingle effect.
Because of the clustering weight, butterflies are not easily dislodged by factors such as wind. Several large telescopes set up around the grove make the clusters easily visible.
Megan Conde, a visitor from Davis, was in awe of the vast amount of butterflies.
“Dude – I can’t believe there are so many,” she said. “I’ve never seen anything like this before.”
The monarchs will leave the grove soon, according to Espiau. He recommends visiting the site as soon as possible because “by the end of February, they’re gone,” he said.
Leong is currently working on trying to manage certain groves. “The conditions created by the trees and surrounding topography will no longer be suitable after the trees grow up, so the butterflies must try to find another place,” he said. “But there isn’t any other place, so it’s very limited.”
After the trees eventually degrade, Leong said that modification of the groves is needed.
“You have to plant more trees; it is called grove enhancement,” he said. “It’s a dynamic process that is the future for the aggregation of monarchs in California.”
The grove is staffed with docents every day from 10 a.m. until 4 p.m. and talks about the butterflies are given at 11 a.m. and 2 p.m.