Recent Boston Globe "monarchs are threatened" article

[Nick Grishin]

Sorry, please ignore, wrong email addresses for my message, profound
apologies, n

On Fri, 9 Jul 2004, Nick Grishin wrote:

> I do not understand, n
> 
> On Fri, 9 Jul 2004, Patrick Foley wrote:
> 
> > Paul,
> > 
> >     I claimed that the Eastern NA migration is more fragile than the 
> > species' viability. You are arguing that it is not fragile at all. I 
> > doubt that. If it were not fragile at all, why is it that so few 
> > butterfly species show any similar migration?
> >     You make an interesting point that migrations reappear in farflung 
> > populations of the Monarch. That is well worth studying. Do you think it 
> > is due to built-in genetically controlled tendencies? Do you think it is 
> > a matter of immediate good decisionmaking by the butterflies? Is it a 
> > vestige or an easily selectively reinforced set of traits? All good 
> > questions. But if the eastern NA Monarchs do not achieve sufficient 
> > Darwinian fitness by their migration, the migration will sputter out. As 
> > it may have in untold other species. And it will sputter out either 
> > because the wintering sites or the feeding sites become compromised.
> > 
> >     If the wintering site for the Eastern NA monarchs has no special 
> > features, could you explain why the Monarchs don't overwinter in all the 
> > closer (to the NA milkweeds) habitats on their routes? I gather that the 
> > cool, but not frigid winter (similar to CA coast) helps to both lower 
> > their metabolism, increasing their lifespans, and thaqt there are fewer 
> > predators in these conditions. The fact that the eastern NA Monarchs 
> > make such substantial migrations, despite their costs, suggests that the 
> > payoff is pretty good, and that they cannot get it cheaper. In 
> > California, such long migrations do not occur, probably because the 
> > overwintering conditions are met along the coast.
> > 
> >     Paul, how are milkweed populations doing in the Midwestern US? You 
> > are pretty sanguine concerning them? Does anyone have any data about them?
> > 
> > Patrick
> > patfoley at csus.edu
> > 
> > Paul Cherubini wrote:
> > 
> > >Pat Foley wrote:
> > >
> > >  
> > >
> > >>But as we have cleared up several times on this list, the Monarch's
> > >>Eastern NA migration behavior is a much more fragile thing. Why?
> > >>1) This kind of migration is not common in butterflies. It
> > >>apparently requires just the right conditions.
> > >>    
> > >>
> > >
> > >Fragile?  I'd say quite the opposite.  During the 19th century
> > >monarchs were inadvertently introduced to several other temperate
> > >latitude islands and continents around the world and
> > >in each case seasonal migrations with overwintering clusters
> > >developed that mirror those in North America.
> > >Examples: southwestern Europe, Australia, New Zealand.
> > >And within Australia itself, seasonal migrations with
> > >overwintering clusters developed in three widely
> > >geographically disjunct regions; Sydney, Adelaide and some
> > >islands between Tasmania and Australia -- in just a matter of
> > >decades.
> > > 
> > >  
> > >
> > >>2) These conditions include the availability of a wintering site with
> > >>special features.
> > >>    
> > >>
> > >
> > >Special features?  I'd say quite the opposite.  In California and
> > >around the world we have seen that practically any kind of
> > >evergreen tree, either native or exotic, will provide adequate
> > >overwintering cluster habitat.  And we have also seen monarchs
> > >overwintering successfully in a rather wide range of climates.
> > >Santa Barbara, California for example, has a considerably warmer,
> > >less cloudy and less rainy fall / winter climate than the San
> > >Francisco Bay Area yet monarchs overwinter by he tens of
> > >thousands in both regions.  And we also see monarchs
> > >overwintering successfully in highly developed and disturbed habitats
> > >such as clumps of trees surrounded by residential subdivisions,
> > >industrial buildings, factories, shopping centers and in cemeteries,
> > >golf courses and city parks.
> > >
> > >  
> > >
> > >>3)  Chip Taylor is certainly correct that the elimination of
> > >>the host plant will end the migration. Surely you are not
> > >>arguing with that statement.
> > >>Presumably you are claiming that milkweed populations will remain
> > >>sufficient in the future even with increased intensity of "weed"
> > >>control. How do you know this?
> > >>    
> > >>
> > >
> > >Well since 1996, the upper Midwest has been the region of the
> > >USA with the most extensive plantings of herbicide resistant crops
> > >and yet this also continues to be the same region with the most
> > >intensive abundance of monarchs.  And last summer there was a
> > >spectacular outbreak of Painted Ladies that occurred in Iowa and
> > >surrounding States http://www.saber.net/~monarch/suv.jpg
> > >In other words, a spectacular outbreak of Painted Ladies occurred
> > >on the very same croplands where herbicide resistant crops are most
> > >intensively grown.
> > >
> > >None of this surprises me because herbicide resistant crops provide
> > >only an incremental improvement in weed control rather than a
> > >revolutionary improvement.  Therefore I think monarchs scientists and
> > >conservationists who tell newspaper reporters that herbicide resistant
> > >crops could "threaten" or "could wipe out" milkweeds and could "threaten"
> > >or "end the monarch migration" are being wildly unreasonable and dramatic.
> > >Just like some of them were behaving 15 years ago:
> > >http://www.saber.net/~monarch/extinction2.jpg
> > >
> > >Paul Cherubini
> > >
> > > 
> > > ------------------------------------------------------------ 
> > >
> > >   For subscription and related information about LEPS-L visit:
> > >
> > >   http://www.peabody.yale.edu/other/lepsl 
> > > 
> > >
> > >
> > >  
> > >
> > 
> 
> 


 
 ------------------------------------------------------------ 

   For subscription and related information about LEPS-L visit:

   http://www.peabody.yale.edu/other/lepsl