Date: 09/23/2010

Number: 1100

Since the 18th of September, our roost sizes have become smaller and the migration rate has diminished. For example, on the 23rd of September, we had a migration rate of only three monarchs per minute moving southwards towards the tip of Point Pelee. In comparison, last week (18th and 19th) we had migration rates of 10 to 15 monarchs per minute. Our roost size on the night of the 23rd was only 1100 compared with roosts of 3,000 to 5,000 on the 18th and 19th of September. The question now is, how many monarchs are left north of us to come through?
Another interesting pattern is that of overnight temperatures. These last few days, overnight temperatures have been very warm -- 17 to 24 degrees Centigrade!!! In comparison, overnight temperatures during the week previous were from 10 to 13 degrees Centigrade. A cold front will move through tonight with temperatures dropping dramatically from 24 last night to 13 tomorrow morning. If this doesn't stimulate a movement of monarchs southwards through Point Pelee, then we can assume that the migation is complete in the southernmost point of Canada.

Leamington, ON

Latitude: 42 Longitude: -82.5

Observed by: John
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