Monarch Numbers in Mexico Up Slightly This Winter

Paul Cherubini monarch at
Fri Jan 30 02:59:03 EST 2009

Last September there were reports on the Journey North website
of hundreds or thousands of monarchs clustering in the Bt 
corn and Roundup Ready soybean growing regions of 
southern Minnesota, Iowa and neighboring upper Midwestern 
States. Examples:

Winthrop, Minnesota 09/06/08 "Our farm was lucky enough
to be a stopping point for hundreds of Monarchs. They 
roosted in the trees each evening for two nights"

Cannon Falls, Minnesota "Aug. 26, 2008 a strong 1,000 
monarchs nectaring in the Monarch Waystation.² 

Redfield, Iowa 09/07/08  "Literally thousands and thousands 
hanging in our trees on our 6 acres with 4 acres of timber."

Griswold, Iowa 09/04/08  "Thousands of monarchs roosting 
in our trees at the golf course."

But late summer monarch numbers were down in the 
rest of the eastern half of the USA as compared to 2007.  

However, the following report written by Biologist Meza Felipe
Martinez, assigned to the area of Biodiversity Research and the
Management of the Reserve of the Monarch Butterfly
Biosphere in Mexico shows the number of monarchs overwintering
in Mexico this year is slightly higher than in 2007. To my
mind this confirms the theory that the natal origins of most of the
monarchs overwintering in Mexico are the Bt corn and Roundup 
Ready soybean growing region of the upper Midwest:

"During this season of hibernation there were 11 colonies
of Monarch butterfly that occupied 5.06 hectares of forest
in the states of Mexico and Michoacan which represents
an increase of 8.89% compared to 4.61 hectares in
December 2007. Again this year there were colonies at
 San Francisco Oxtotilpan and Contepec. The colony with
the largest occupied area was the Ejido El Rosario with
 2.37 hectares followed by the colony Cerro Prieto in
the Sierra Chincua (1.0 hectare). Notable is the absence
of colonies was the region of Cerro Pelon, compared with
 the previous season, because in this season only the
colony in Ejido Nicolas Romero was occupied. During
this season there has been significant frost, but with
no rain or winter storms, which has contributed to the
good of the populations of the butterfly."

Paul Cherubini
El Dorado, Calif.


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