Date: 10/24/2011

Number: 1300

In the ten years that I've been working as a naturalist at Point Pelee National Park, I have never observed roosts of more than two or three hundred later than the 9th of October. So I was surprised to see a roost of 900 monarchs yesterday (23rd Oct.) Then today, a migration rate of 10 monarchs per minute flying southwards through the park with a roost of 1300 tonight (24th Oct.) And with a sunny day tomorrow, this may continue.

It is true that the last half of August and the first week of September has been warmer than normal, allowing late caterpillars to complete their metamorphosis to the adult stage, giving us this late migration.

In addition, we have experienced October weather in September this year with 7 extra days of rain above the normal for September. Add to this 8 days of rain from the 12th to the 20th of October and you get a total extra migratory delay of 15 days. Here at Point Pelee we usually get a pulse of migrating monarchs in the first week of October with roosts of about 1,000 butterflies. The extra rain this year could easily account for this late pulse to arrive here two weeks later than normal.

The danger for monarchs migrating in late October is strong winds (as we've seen from last week's report on Journey North) and the first frosts of the fall season. We have had our first frost this past Saturday the 22nd October. So these monarchs are really living on the edge. We wish for them a steady breeze from the northeast and sunny days to speed them on their way to join their friends who are already in Mexico.

Leamington, ON

Latitude: 42 Longitude: -82.5

Observed by: John
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