Thousands of Monarch butterflies have made their way to Goleta’s Coronado Butterfly Preserve in the past month as part of their annual migration from the Colorado foothills.

The Coronado Butterfly Preserve is a 9.3-acre reserve protected by the Santa Barbara Land Trust. The area serves as a mating spot for the Monarchs during their migration journey, which spans two or three generations as the insects work their way northward.

During the butterfly mating period, Monarchs fall into a semi-hibernation state that allows them to prolong their lifespan from two months to seven or eight months. The insects can be found in clusters of over 100 in the branches of eucalyptus trees in the preserve, which is open to the public.

“The reserve is a great place for the Monarchs and community members,” said Monarch butterfly docent Sharon Lang. “We get a lot of people here — students and citizens — who desire to learn more about the Monarchs and how Coronado helps them to mate and rest during their migration.”

The Coronado Preserve protects a number of indigenous flora and fauna in the area, but, according to Lang, the non-native eucalyptus trees have been allowed to thrive due to the benefits they provide the mating Monarchs.

“Although the eucalyptus is a non-native organism, it is very much beneficial to the Monarchs,” Lang said. “It provides a canopy that insulates and keeps them warm while they are in their semi-hibernation state.”

Despite the efforts of the preserve, the number of butterflies has declined this year. Roughly three to seven thousand butterflies found their way to Coronado at the beginning of the migration period, as compared to twelve thousand who flew in last year.

According to Lang, the decline is most likely due to natural causes.

“We are not completely certain as to why their numbers went down, but there are some theories,” Lang said. “Parasites — most likely flies — laid their eggs on the larva last year which may have brought down their numbers. The rainstorm last week also caused butterflies to leave, although some of them did end up returning.”

Despite the decrease in butterflies, community members are still visiting the preserve to observe the thousands of insects who have returned.

Aaina Schempp — a visitor who made the two hour drive from Los Angeles with her boyfriend — explained that her experience last year brought her back for a second time.

“We’ve spent 40 minutes here already and I’m so glad I came back again,” Schempp said. “The Monarchs are beautiful and it’s really a perfect way to spend a day.”

The City of Goleta’s Monarch Butterfly Docent Program organizes volunteer docents to provide information to the public from December-February during the pinnacle of butterfly viewing. Docents at the Coronado Preserve are available to answer questions from the public and group butterfly presentations can be arranged through City Hall.