For years the Monarch Scientific Community has claimed: http://www.monarchwatch.org/biology/westpop.htm "There are two geographically distinct Monarch populations in North America. The eastern population overwinters in Mexico and breeds east of the Rocky Mountains. The western population overwinters along the California coast and breeds in areas west of the Rockies." And they published maps like these: http://i85.photobucket.com/albums/k75/4af/karen.jpg http://i85.photobucket.com/albums/k75/4af/altizer.jpg http://tinyurl.com/adrlwd leading us to believe monarchs breed only "east of" and "west of" the Rocky Mountains and don't mix during migration.
We now know those claims are innaccurate. See this article: http://tinyurl.com/cfp69p SCIENTISTS CONFIRM MIXING BETWEEN EAST AND WEST POPULATIONS OF MONARCHS Excerpts: Six rebel monarch butterflies who haven't done their homework seem to have disproven a long-held theory that monarchs east of the Rocky Mountains in Canada and the U.S. migrate to Mexico for the winter, while their western cousins hang out in California during the cold months. "This totally blows out of the water (the theory) that there is some sort of hard dividing line between the east and west populations," said Chris Kline, a scientist and former teacher who heads the Southwest Monarch Study. Three monarchs tagged in southern Arizona (west of the Rocky Mountains and just north of the Mexican border) were recovered in California, but another three tagged in Arizona were found in the overwintering colonies in Mexico. http://i5.photobucket.com/albums/y189/mastertech/237Vd.jpg "Monarchs in Arizona obviously haven't read the textbook - they're going both directions," said Kline, who was education director at the Boyce Thompson Arboretum in Arizona before moving recently to Columbus, Ohio, where he is education director at Grange Insurance Audubon Center. "Obviously they're not playing by the same ground rules as all the other ones are." Kline has team members in Mexico searching for his distinctive light blue tags - tiny stickers placed on a particular spot on a butterfly's hindwing that are considered not to harm the insect. Other tagging programs, such as Monarch Watch's, use white tags. "The old theory was that the Continental Divide was the magical dividing line, which means I have had three that have flown the wrong way," he said. A more recent theory is that the dividing line runs from Boise, Idaho, to Yuma, Ariz., which means the other three have flown the wrong way. Kline has had monarchs recovered in Mexico and California in recent years, but he said the results weren't taken seriously because the butterflies were farm-raised and their navigational systems may have been mixed up. "Now we've got two wild butterflies that have done the exact same thing as what those farm-raised ones released in Phoenix did, which I think adds more credence to the issue," he said. One wild monarch was tagged in Canelo, Ariz., and recovered in the El Rosario monarch reserve in Mexico. http://i85.photobucket.com/albums/k75/4af/157xb.jpg http://i85.photobucket.com/albums/k75/4af/157Xa.jpg The other was tagged just 12 miles southwest of Canelo in Bog Hole, Ariz.,but recovered in Ellwood Main, one of several overwintering sites near Santa Barbara, Calif. http://i5.photobucket.com/albums/y189/mastertech/237aa.jpg http://i5.photobucket.com/albums/y189/mastertech/237ac.jpg Paul Cherubini El Dorado, Calif.
