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When
Will the Fall Monarch Migration Reach You?
The Timing of Fall Migration
Example:
When
do monarchs begin to roost in the following places?
Answers:
Based
on Journey North records from 2002 to the present, roost will be
forming in:
-
Ontario:
Before August 30th
- Illinois:
- Before
September 5th (northern Illinois)
- Before
September 19th (southern Illinois)
- Oklahoma:
- Before
September 19th we can expect the first few to appear, by September
26th there will be more, and more by October 3rd.
- Texas:
- By
September 19th the first roosts might be present. The number
of roosts will climb each week and between October 3rd and
17th the peak number of roosts will form.
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Some
Notes:
- The
timing of migration is remarkably consistent from one year to
the next.
- If
you don't want to miss the migration, begin to watch before the
dates that roosts traditionally form, based on the records on
this map.
- Roosts
can last from one day to as many as two weeks.
- Roosts
can be large (hundreds or thousands of butterflies) or small (a
handful of butterflies).
- Roosting
behavior is assumed to be associated with migration. However,
the behavior could begin before migration. It has been seen "pre-migration"
in areas with good nectar supplies. Much remains to be learned.
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Monarch Butterflies
