Mexican Monarch Overwintering Population size is normal this winter

Paul Cherubini monarch at saber.net
Thu Jan 16 15:00:22 EST 2003


It's official now.  Formal censusing of the Mexican monarch overwintering
population is nearly complete and the populations have been found to be normal
in size despite the unprecedented storm related mortality that occurred last winter. 
http://www.sbcnews.sbc.edu/0202/0202nytbrower.html  Articles about this 
population recovery, including the census figures, will likely appear in the New York 
Times and other media outlets in February.

This great monarch recovery is a surprize to the monarch experts who last winter 
had speculated it might take "several years" for the monarch population to recover. 

For example, on Feb. 12, last winter Dr. Chip Taylor of the University of Kansas
wrote the following on his website:

"The bottom line for now is as follows: If there were 1.29 hectares, or fewer, 
butterflies at Chincua and Rosario at the end of January and if the outlying colonies 
were hit as hard or harder, this means that end of January pop this yr is less than
half as large as it was last year at this time - a time when the pop was at its known all 
time low. If the remaining butterflies are in poor condition, the recovery could take 
several yrs.  The conditions this coming spring are not as favorable as they were last yr. 
The fire ants population in the south are up and soil moisture is down over much of the 
Midwest and these factors limit the growth of monarch population."	

And Dr. Karen Oberhauser, a monarch ecologist from the University
of Minnesota stated in http://www.sbcnews.sbc.edu/0202/0202nytbrower.html  

"A bad winter followed by a bad spring could be catastrophic" 
 
Well, it turned out the spring WAS bad for monarchs and on June 6, 2002, Dr. 
Chip Taylor wrote:

"It is still too early to predict the fall population, but the surge of  new monarchs 
that signaled the recovery of the population after the winter of 2000-2001 has not 
occurred this spring. I have only seen 7 monarchs this spring and this is certainly
my all time low for this far into the season."

Thus, just as we saw during the great monarch recovery in the summer of 2001, 
monarch survival during the overwintering period in Mexico just isn't very critical to
the continuation of the migratory phenomenon. Even if we intentionally wanted to 
erradicate all migrating monarchs and killed 80% of them with insecticides at the 
overwintering sites in Mexico, normal numbers would likely return the following 
winter.

Paul Cherubini
Placerville, Calif.

 
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