Monarchs Move Out

The monarch butterflies, including 36,000 with tiny identification numbers on their right wings, are moving out from their coastal winter roosts, as they always do at this time of year. As their movements are traced by the tags on their wings, new and surprising facts about their activities are emerging.

“We have confirmed this year what we have suspected--that the migration begins with the southernmost clusters,” Chris Nagano reported from the Los Angeles County Natural History Museum, where he coordinates the study of the monarchs. “But instead of all moving north, as we had thought, there is more of a shotgun migration--movement in a real random fashion, flying until they find the environment they require.”

The target is milkweed, on which the female lays her eggs because it is the favored food of the caterpillars that will emerge.

The most impressive flight reported so far this year is a monarch that flew 28 miles in a single day, from Big Sycamore Canyon near Point Mugu to Rustic Canyon in the Santa Monica Mountains. The easternmost flight recorded this year took a monarch from its winter roosting site in Rustic Canyon to San Bernardino.

Nagano depends on sharp-eyed citizens to note the wing numbers, locations and dates of monarch sightings. If a banded butterfly is found dead, most people mail the insect to the museum with a report of the date and location. Sometimes Nagano receives a helpful letter, like one written last month by Long Beach Police Lt. C. G. Shelly. “Your butterfly was engaged in breeding with another monarch on the lawn of the Long Beach Police Academy,” Shelly reported. “The two butterflies were detained long enough for information to be copied from the tag and then they were released unharmed.” The butterfly had been tagged in Rustic Canyon 12 weeks earlier.