Monarch Mexican Migration and land management
patfoley at csus.edu
Thu Nov 20 18:57:40 EST 2003
Are you suggesting that we need to know more about the appropriate land
management policy for Monarch winter sites and more about the autecology
of overwintering Monarchs?
That sounds good to me.
Or are you suggesting that everything is cool because the Monarchs are
still there? And that open canopy must be good for them because they go
to open canopy? And that old forests are bad because they get lots of
insects and fungi? And that Brower and his team are fools or scoundrels
for trying to study Monarch autecology and land use? And that
contemporary tree poaching is pretty much what it was three hundred
years ago so that no new attention needs to be given to the issue even
with Mexican population and economic pressures rising so steeply.
That sounds dumber than I think you are.
I am perfectly willing to give you credit for your observations and
insights about Monarch roosting behavior and the possibility that the
Brower group is overly committed to a simplistic model. But if your
alternative to the Brower model is to do nothing, to protect nothing, to
malign researchers who open themselves to criticism by publishing
peer-reviewed research, and to ignore their actual accomplishments, then
what honest person will want to take your side?
Paul Cherubini wrote:
> Pat Foley wrote:
>>I will agree with Paul and Jurgen that natural forests are mosaics of
>>patches in various stages of succession. And that this heterogeneity
>>is a good thing for the biodiversity and for various ecosystem processes,
>>including insect pest and pathogen regulation.
>>Next we need to determine the historical landscape heterogeneity
>>pattern, and develop land management practices to imitate it.
> Pat, despite the fact that monarchs have overwintered successfully in the selectively
> logged forests of Mexico for centuries, Brower's team does not believe these
> thinned forests are good habitat for the monarchs. Their position is "logging
> not only removes roost trees, but opens the forest to wind and weather,
> dangerously exposing the monarchs." Brower's team studied monarch clustering
> in open and closed canopy areas of the forests and found:
> "Monarchs that were clustered in open areas experienced lower ambient
> temperatures during the night, higher wind velocities, higher rates of water
> evaporation, higher rates of lipid use and higher rates of bird predation than
> monarchs clustered in closed areas. All of these factors contribute to earlier
> mortality in overwintering monarchs, mainly through dessication and
> So although monarchs commonly display a clustering preference
> for open canopy areas, even when closed canopy areas are available
> http://www.saber.net/~monarch/chincuamissrie.jpg (photo lifted
> from Journey North website)
> http://www.saber.net/~monarch/chincuacar1.JPG (photo courtesy of Carol
> http://www.saber.net/~monarch/opencan.jpg ((photo lifted
> from Journey North website
> Brower's team appears to believe would be better if the holes in the forest were
> sealed up and the butterflies were all forced to all stay in closed canopy areas.
> Mike Quinn also seems to think it's wrong to let the butterflies cluster in
> open canopy areas, even if they want to, when he wrote on dplex-l in 1998:
> "Paul, it is morally bankrupt to suggest that, if an animal uses a habitat
> where it will experience an increase in mortality, then it's _okay_ to create
> _more_ of this habitat."
> In summary, we have a situation where even though the selectively
> logged forests of Mexico have sustained the monarch migration
> for centuries, and even though monarchs commonly display a clustering
> preference for areas of the forests with holes or openings of some kind in
> the canopy, not even selective logging is allowed anymore in the "core
> [cluster] areas" of the monarch reserves. Further, Brower's team
> has designated large areas of the reserves as "degraded" not because
> they have actually been deforested, but simply because the forest canopy is
> not fully closed or almost fully closed.
> Paul Cherubini
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