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Wednesday, 16 August 2006 00:00

Monarch migration

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The king of insect migration – King Billy – will soon be gliding its way to Mexico by the millions. The monarch butterfly was dubbed “King Billy” by early North American settlers because its bright orange color reminded them of William of Orange, King of England.

Every fall the skies fill with royal orange as masses of North American monarchs waft, sail, glide and flap their way unerringly to a wintering ground they have never seen. The western population of monarchs in North America overwinter in California from Mendocino County south to San Diego. The eastern population makes it all the way to central Mexico, a trip of more than 2,000 miles for some individuals. One butterfly tagged in New York’s Central Park on August 27, 2005 was recaptured at El Rosario Monarch Sanctuary on February 14, 2006 – a trip of 2,150 miles.

Monarchs take advantage of thermals and updrafts as they bump their way to Mexico. The Southern Appalachians make a great corridor for the monarch’s fall migration.

The peak of monarch migration across Western North Carolina is from around Sept. 25 through Oct. 7. Observing migrating monarchs requires patience and/or luck. Either way, you have to be in the right place at the right time. Most of the time monarchs migrate individually or in loose flocks across a broad front. If you are in a flight path on a good day, you might easily see 20 to 30 butterflies an hour. While the precise migration path is somewhat random based on prevailing winds and weather conditions, there are traditional hot spots as the butterflies congregate at mountain passes. A couple of traditional monarch hotspots in the area are Cherry Cove Overlook at milepost 415 on the Blue Ridge Parkway and Wagon Gap at milepost 412.

Large flocks of migrating monarchs are rarely encountered in Western North Carolina, but it can happen. A few years back I was lunching with a group of fellow hawk watchers at the Pink Beds, off of U.S. 276 in the Pisgah National Forest just north of Brevard. We had birded the Blue Ridge Parkway that morning looking for migrant passerines and were headed to Caesar’s Head State Park in South Carolina to watch for migrating raptors. We began to notice monarchs flapping by, finished lunch, and moved to larger, open areas. There, from treetop level to as high as we could see, were hundreds (if not thousands) of monarchs searching for thermals. And there were probably more, higher still, that we couldn’t see. Monarchs have been recorded during migration at heights of more than 11,000 feet. It was a sight I will never forget.

As fall approaches many birders will be chasing migrants. Adding a little butterfly watching to the agenda is a great way to either extend the day or if you’re one of those hardcore dawn to dusk birders, it can help fill that midday slump. Whether you’re a birder butterfly-watching on the side or whether your goal is observing monarch migration, you’re observations can add to a wonderful citizen science project. Just go to www.learner.org/jnorth/ and follow the monarch links. They even have a downloadable migration form. Monarch Watch at www.monarchwatch.org is also a great place for information, events and activities geared towards learning about this incredible insect.

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