Date: 08/27/2009

Number: 1

Lakes Ontario and Erie act as barriers to the monarchs' southward movement, so the butterflies travel southwestward along the north shore of these lakes towards our national park here at Point Pelee.

August 23

Cold overnight temperatures of 10 degrees centigrade last Sunday night August 23rd here in Leamington stimulated a southward movement of Monarch butterflies from north of us.

August 27

A 15 km/hr wind from the northeast on Tuesday and Wednesday (25 & 26 August) helped these butterflies along and we received our first wave of migrants on Thursday afternoon the 27th of August. We counted from 700-1,000 monarchs roosting at the southern tip of Point Pelee on Friday morning the 28th August. The butterflies will wait here until the wind dies down and then they will fly across the lake to Ohio.

August 30

The temperature tonight on the 30th August is forecast to drop to 8 degrees centigrade which will stimulate more monarchs to move in our direction bringing us another wave of migrants in a couple of days.

August 31
Our roost here at the tip of Point Pelee stayed for three days while the winds were fairly strong. On Monday morning the 31st of August, calm conditions allowed these butterflies to cross Lake Erie to Ohio.

September 2

We now have no butterflies roosting and only small numbers of monarchs nectaring on spotted knapweed along the lakeshore. I'll let you know when the next wave of monarchs moves through.

The following update was written on September 28th

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.

September 20

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.

September 27

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.

September 30

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 Longitude: -82.5

Observed by: John
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