Date: 09/15/2011

Number: 1500

Over the past ten years, we have welcomed our first migratory wave of monarchs 75% of the time during the first week of September here at Point Pelee National Park.

This year, we got our first sharp drop in overnight temperatures on the 5th of September -- right on schedule. This should have stimulated thousands of monarchs to move southwards and through Point Pelee. However, clouds arrived at four o'clock that same day and an unusual stationary low pressure system settled in, bringing rain and cloudy weather for five consecutive days. Very few monarchs moved in such weather. But I noticed that out west, monarchs did move southwards at this time.

Our next sharp drop in overnight temperatures came on the 14th of September, this time followed by sunny days and winds from the north to help them along. Thousands of monarchs moved through the park on the 15th and 16th, with nighttime roosts of 1500 and 850.

On the 17th, with warmer temperatures and cloudy weather, the monarchs decided to stop moving and begin nectaring to build up fat reserves for the migration and for the hibernation in Mexico.

Leamington, ON

Latitude: 42 Longitude: -82.5

Observed by: John
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