Date: 09/27/2009

Number: 700

We have had two waves of monarchs migrating through Point Pelee National Park so far this year: the first in late August and the second in mid-September.When we had a cold overnight temperature of 10 degrees Centigrade on September 20th, we expected to get another wave of migration, but only a few monarchs showed up. So, we decided that the migration was over for this year. We did have a cool, wet spring and early summer, and all butterfly species were present in lower abundances this year.

However, on the 27th of September, by 10 o'clock in the morning, we had a small movement of three butterflies per minute moving southwards along the shores of Lake Erie. This was totally unexpected by us because the overnight temperature was a balmy 14 degrees Centigrade, and the wind was from the west at 15 to 20 km per hour. We normally get a migration with cold overnight temperatures and a gentle wind from the north. By 5 o'clock, we had about 700 monarchs roosting at the southern tip of Point Pelee. The winds increased dramatically to blow from the south at 50 to 60 km/hr. over the next few days and these monarchs stayed put. On September 30th, in the afternoon when the winds quieted to 10 km/hr. from the north, our monarchs flew across Lake Erie (40 km.) to Ohio and on to Mexico.

Leamington, ON

Latitude: 42.1 Longitude: -82.6

Observed by: John
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