Trees used by Monarch butterflies in California

Paul Cherubini paulcher at
Wed Sep 23 07:11:14 EDT 1998

Sometimes monarchs form their overwintering clusters in trees with
little or no foliage.  This happens in Refugio Canyon near Santa
Barbara, California.  The canyon in filled with willow and western
sycamore trees. There is not a eucalyptus tree in sight.  From late
December to late January the trees have little or no foliage and the
butterflies can be found clinging by the thousands to bare twigs and
limbs.  This may have been a common phenomenon along the California
coast prior to the introduction of eucalyptus. In areas of the coast
where eucalyptus groves are available, the butterflies will almost
always cluster on them instead of the locally available native
vegetation.  This is a fustrating fact for the anti-exotic folks who
seem to feel that natural selection should make the monarchs "want" to
prefer native vegetation for roosting.

Another fact of monarch behavior that fustrates the "natural is always
best" folks is that the numbers of monarchs overwintering in a grove of
eucalyptus trees can sometimes greatly increase if one cuts out a large
house sized hole in the grove.  When a home or industrial building is
constructed inside a dense eucalytpus grove, the numbers of butterflies
coming to the grove can rise dramatically.  This fact of monarch
behavior is another issue that puts anti-development activists between a
rock and a hard place.  The concept that residential or industrial
development inside a eucalyptus grove could enhance the butterfly
habitat seems to be sickening to them.

This all seems to me to be a matter of our western society cultural
conditioning. We are taught that we OUGHT to be sickened by such
phenomena as a native butterfly prefering an exotic groves of roosting
trees and OUGHT to think it is totally impossible for development to
enhance a roosting habitat. 

Paul Cherubini, El Dorado, California
paulcher at

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