Danaus plexippus

When I stared up into a thousand-butterfly cluster hanging from a eucalyptus tree, mouth gaped in wonder, a hundred questions raced through my mind, but the most prevalent was “Do monarch butterflies poop?” Close your mouths because the answer is yes. Other questions about the monarchs in the Ellwood Grove emerged, such as how did they get here? Why here? And what are those butterflies doing together on the ground?

“They’re making babies,” a three-year old exclaimed to another child, educating other visitors and myself.

The Ellwood Grove is one of the more awesome places to visit in Santa Barbara County, serving both as a place of education and as the largest over-wintering site for monarch butterflies of the hundred that are located across Santa Barbara County. The grove houses hundreds of thousands of butterflies between October and March and is located less than three miles from Isla Vista.

Migration

Butterflies migrate to the California coast in the fall and will aggregate in “over-wintering” sites from October to February in a state of reproductive shutdown known as diapause. The monarchs will rely on the body fat they stored as caterpillars to survive

Many theories about where and when monarch butterflies migrate still exist and scientists are still debating whether monarchs navigate or not. UCSB Professor Emeritus of Natural History Adrian Wenner taught a course in entomology for more than 30 years and found that monarch butterflies could stay in California year-round based on the distribution of milkweed growing in many sites including the Red Rock area and in the Santa Ynez Valley.

“They have been trying to prove since the ’40s that monarchs can navigate long distances,” he said. “I expected scientists to be very happy that we had monarch butterflies here all year, but no they were very angry. I’ve been in trouble with the butterfly people since.”

Wenner began studying the local monarchs’ movement patterns in the 1960s after he observed them flying from east or west depending on the time of the day. At the time, scientists who studied monarchs thought the monarchs in Santa Barbara only migrated here, sometimes from Idaho and Canada.

Wenner worked with undergraduate and graduate students to collect milkweed samples from Red Rock and the Santa Ynez Valley. They collected enough data to find that, based on milkweed distribution, monarchs lived in California year-round, but stopped reproducing and laying eggs by fall.

Monarch butterflies from Mexico can spread their range to the United States in the fall, by taking advantage of weather patterns, Wenner said. High-level jet streams move from southern Mexico, where the butterflies originate, in a northerly direction to the U.S. The monarchs use the drafts created from this system to spread their range before finally aggregating during the winter.

“All they would have to do is go up in the air and they move 150 miles an hour,” Wenner said.

In the Habitat

Butterflies cannot survive below freezing temperatures, but a habitat that is too warm could waste their energy. Over-wintering sites have to provide a microclimate that can shelter from the wind, stay cool on warmer days and retain warmth on cooler days. The monarchs also need moisture and will drink the dew that forms from coastal fog.

Any disturbance to the trees or leaf litter on the ground can change the microclimate of the grove just enough to make it unappealing for the butterflies, said David Lange, a member of the Monarch Program, a San Diego-based education organization. Members from the local chapter of the Monarch Program put up ropes last year to stop visitors from entering the ravine area and causing erosion.

The butterflies have become increasingly popular with elementary school groups and visitors, causing local groups to be concerned that too many visitors may disturb the butterflies. The Coronado Preserve Advisory Group is a local group that runs the Coronado Preserve north of the site and provides educational material on the monarch butterflies. Associate Research Biologist Jack Engle, a member of the advisory committee, said visitors to the site should be careful not to disturb the Monarchs by stepping on them or disturbing the clusters.

“If they’re disturbed, they may be flying at times they shouldn’t be or wasting energy when they shouldn’t be,” he said.

Butterfly Orgies

Monarchs reproduce by making contact in the air and falling to the ground as the male holds on to the female with the anal claspers. Male monarchs can be distinguished from females because of their scent gland, a black dot on the hind wing. Females and males will participate in a large orgy during the first two weeks of February, when Wenner said he observed 120 pairs falling to the ground in a half-hour period.

After the orgy, females will search for milkweed to lay the eggs and the males die a few weeks later. Though monarchs drink only nectar, monarch caterpillars can only eat milkweed. The caterpillars will absorb the bitter taste from the milkweed, which makes them poisonous, but not deadly, to predators.

The caterpillars eat 25 times its own body weight before they enter into the chrysalis. Monarchs live anywhere from six weeks to eight months, once the 30-day cycle from hatching to butterfly takes place. The butterflies in Ellwood, in a state of sexual diapause, will live about six months, five months longer than at other times of the year, Lange said.

Environmental Issues

Lange has been involved in efforts to stop development around the Ellwood site for the past 14 years. The Santa Barbara Development Partnership owns the land around the butterflies and environmentalists and local groups have been fighting against development along the bluffs for over a decade. Currently, the county has proposed a land swap that would compensate the developers with land in another part of Ellwood, but Lange said with the new city of Goleta and the moratorium on development, plans are still up in the air.

Lange said the butterflies are worth preserving.

“They’re just like – if you could imagine something perfect – they’re as close to perfect as you could imagine,” he said.