[leps-talk] Why aren't Mexico's overwintering monarchs in the news yet this winter?

[Paul Cherubini]

Kurt Johnson wrote:

> still does not solve the problem of a circa 50% loss of 
> available forest land for overwintering in Mexico.
> Are you suggesting that the maps showing this historical 
> decline are ficticious?

Paul Cherubini responded:

> I don't understand your point. My point is that the census
> data indicates the size of the monarch overwintering 
> in Mexico has been stable from 1985-2001

Kurt Johnson follow up:

> I was referring to the demographic maps that showed 
> the shrinkage of Oyamel forest in the overwintering 
> areas over the years, long-term.  It would seem to me 
> that such a decrease is, itself, alarming... e.g. if it
> would continue, where would all those Monarchs go?

Cherubini follow up:

Since the monarch population has remained stable over the past
30 years while the forest has shrunk 50% I think a reasonable 
conclusion is that the 50% loss of forest was not harmful to the 
butterflies. 

Now if conservationists had stepped in 30 years ago to prevent
this 50% loss it would have deprived the 50,000 humans living 
in the immediate area from clearing the 50% to grow
their food, graze their farm animals, build their homes, schools, 
churches, roads, etc. yet would have done nothing to conserve 
monarch butterflies since the 50% forest portion removed was not 
really butterfly critical butterfly habitat to begin with.

Also, we should  consider if the patches of cleared forest could 
provide potential benefits to the butterflies. Like do the clearings 
provide a nearby source of drinking water and flower nectar?  Judge
for yourself:

http://www.saber.net/~monarch/meadow.JPG
http://www.saber.net/~monarch/child.JPG

> Are you suggesting that the maps showing this historical 
> decline are ficticious?

In my opinion, the satellite and ground photos of the overwintering 
sites taken over the past 25 - 30 years do not support your statement
that there has been a "50% loss of available forest land for 
overwintering in Mexico."

For example, here are the historical 1973 vs 2000 infared satellite 
photos of the two main overwintering colonies in Mexico where 70% of 
the monarchs overwinter. http://www.saber.net/~monarch/changes1.JPG

Red =            forest
Tan =            bare ground (farm land or meadows)
White dots = known colony locations over the years
White lines = butterfly reserve boundaries (the old ones)

Llittle change in the forest coverage is evident.

Paul Cherubini

 
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