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Here come the monarchs.

On wispy wings, monarch butterflies by the millions migrate to coastal California

In the kingdom of insects, the monarch butterfly has earned its crown as a traveler. The monarch (Danaus plexippus) is the only insect species known to make a long-distance migratory round trip.

And what a trek it is! On wings that resemble orange-and-black stained-glass windows, the monarch may travel as far as 3,000 miles and reach altitudes up to 10,000 feet on its way to the frost-free havens where it spends the winter. Cruising at an average of 12 mph, the monarch may take weeks to make the trip. Yet despite the arduous journey, millions of them migrate south from states west of the Rockies to overwinter along the California coast.

Though their numbers fluctuate, monarchs are abundant throughout the United States and Canada. The Pacific population alone is estimated at 1 to 3 million. Last winter, monarch populations declined markedly at all the California roost sites; scientists hope this decline is part of a natural cycle and that the insect's numbers will soon return to normal.

In the realm of the monarchs

Monarchs are easy to find: each winter, they home in on the same communal roost sites in sheltered groves of Monterey pine, Monterey cypress, and eucalyptus. The hordes begin arriving by late October or early November. They rest and mate, and by late February or early March, they somehow know it's time to head north.

Exactly how monarchs find the same sites each winter is something of a mystery, since members of each migrating group are the descendants of the previous year's migrants. It is believed the entire journey is based on instinct. Most scientists presume that monarchs, like birds, whales, and other migratory animals, find their direction using sun orientation. Still others contend that monarchs may use magnetic fields for orientation, since their bodies contain magnetite (a magnetic iron oxide).

While their navigation methods may be in question, their taste in real estate is not: monarchs overwinter at some of California's priciest coastal addresses, from Mendocino south to Pismo Beach. But the butterflies are particular by necessity, since roosting groves must be in areas free of killing frost and offer nearby fresh water and nectar-producing plants. Trees must have leaves or needles shaped so the butterflies can grasp the foliage and hang in clusters as they seek shelter from winter winds and cool temperatures.

In 1988, Californians passed an initiative that included a $2-million allocation to preserve groves where monarchs overwinter. Experts selected the top 10 sites and the state set about buying the land. To date, the state's Wildlife Conservation Board has purchased or helped protect four sites, including a major roosting site in Pacific Grove, where voters passed their own $1.2-million bond to complete the purchase.

Your own migration to see the monarchs

If you visit one of the monarch groves on a sunny day this winter, you may see clouds of the butterflies fluttering on and off the branches. They have trouble flying at low temperatures, so on cool days watch your step--the floor of the grove may be littered with fallen monarchs,

In January and February, the monarch begins its mating ritual, in which the male captures the female, and they flutter to the ground and mate. Then, in a postnuptial flight, the male carries the female beneath him.

Later, on the northbound journey, females lay their eggs on milkweed plants. In 4 to 12 days, caterpillars hatch, and in another three to four weeks, the butterflies blossom. Some scientists think the adults of this generation and the next one, which each live four to six weeks, continue northward through the summer. By the time the third, fourth, and fifth generations of monarchs have emerged, it is fall and time to migrate south; these latter generations live up to six to nine months.

We list the top public sites, from north to south. Before visiting, call for hours and directions.

Fremont: Ardenwood Regional Preserve, (510) 796-0199.

Santa Cruz: Natural Bridges State Park, (408) 423-4609.

Pacific Grove: the major roosting grove is next to the Butterfly Grove Inn, at Lighthouse Avenue and Ridge Road; park on the street and follow the path to the viewing area. Call the chamber of commerce at (408) 373-3304.

Near Carmel: Point Lobos State Reserve, (408) 624-4909.

Morro Bay: Morro Bay State Park (in campground); call the Morro Bay Museum of Natural History at (805) 772-2694.

Pismo Beach: Pismo State Beach at North Beach Campground, (805) 489-1869.

Near Malibu: Point Mugu State Park at Big Sycamore Canyon Campground, (818) 880-0350.
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Title Annotation:The West's Great Fall Migrations; butterflies
Author:Finnegan, Lora J.
Date:Nov 1, 1993
Previous Article:Scenes from the flyway.
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