Monarch Butterfly Migration Update: May 23, 2002
Today's Report Includes:
News From the Migration Trail
to Data: Link
to This Week's Migration Data
- Migration sightings picked up again this week, but only slightly.
This week's 25 sightings compare to 75 sightings during the same week
- This spring's migration map now shows the most dramatic contrast
from last year's. Notice the differences in both the abundance of
monarchs and the advance of the migration.
- Curiously, 40% of this week's reports were from Iowa. There the
migration has now advanced to about 43 North-some 60 miles ahead of
its position last week.
- In the East, monarchs have now been reported from as far as 41
North. Again this is only about 60 miles ahead of its position last
- We're still waiting for the first report from Canada. Last year's
first was May 2nd, now three weeks ahead of today's date.
- Most everyone noted fresh wings on the butterflies they saw. Now
that it's late May, we can safely assume all sightings were of the
new spring generation. These "first generation" sightings
are marked on the migration map with a black dot in the center. Thus,
the map shows how far the generation from Mexico advanced this spring.
Cool Weather Halts Advance into Northern
It was the unusually cool weather last week that essentially stalled the
northward advance of the migration. As the strong high pressure system
responsible moves eastward, south winds and warmer temperatures will follow.
(See maps below.) How far north do you predict the monarchs will have
been sighted by next week at this time?
Pressure Moves East
Generations: Which Generation Will Go to Mexico in the Fall?
Spring is the beginning
of the monarch's breeding season. The monarchs that migrated north from
Mexico in March are of a very unusual generation. They do not breed
until they are 8-9 months old--and not until after they have survived
two migrations and a long winter in between. In contrast, during the
summer breeding season, monarchs live for only 2-5 weeks! Several generations
live and die each summer, and it's the final generation that migrates
to Mexico in the fall.
Using the worksheet below, you
can figure out which generation migrates to Mexico. Here is the question:
Of the monarchs that spent last winter in Mexico, do you think this
fall's migratory generation will be:
- their children?
- their grandchildren?
- their great-grandchildren?
- their great-great-grandchildren?
- their great-great-great-grandchildren?
- their great-great-great-great-grandchildren?
&you have the idea, now see
if you can calculate the answer!
Tuned: The Monarch Migration Continues!
Other Journey North migrations have come to an end, but we'll continue
to track the monarchs until they ve expanded across their entire breeding
range. This normally takes until mid-June, but may take more time
this year because the population is so low.
YOUR Monarch Sightings Are Important
This is an ESPECIALLY important year to be watching for monarchs. Even
after monarchs have been reported from your state or province, we want
to hear from YOU when you see YOUR first! And, if you don t see your
first monarch until later in the summer, please report it then. The
number of sightings reported reflects monarch abundance, so your observations
will continue to be important.
The Next Monarch
Migration Update Will Be Posted on May 30, 2002
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North. All Rights Reserved.
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