Recent Boston Globe "monarchs are threatened" article

Paul Cherubini monarch at saber.net
Fri Jul 9 13:33:31 EDT 2004


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 
 


More information about the Leps-l mailing list