Date: 07/22/2001

Number: 1

During the last week monarch numbers have increased dramatically here in Minneapolis, MN after the emergence of a new generation. On Saturday I was amazed to observe very clear, directional flight all during the day. These observations were made on the southern shore of a lake, meaning that the butterflies had just traveled southward 1 mile across the lake when I saw them. As many as one monarch per minute passed by at various times. When the monarchs reached the shore they exhibited strong flapping flight so as to gain altitude some 40 feet in order to fly up and over the bank and trees.

The behavior was IDENTICAL to the migration patterns we observe during mid to late August, making me wonder: Were these butterflies migrating? Do monarchs that emerge in late July typically begin to head southward? (And was it just noticeable on Saturday because so many had emerged during a short window of time?) Or, are milkweed conditions poor due to drought this year, so that an early southward dispersal is occurring?

Wind conditions varied, between easterly and southerly flows during the day, and at times there was no wind at all. However, just as they do in August, the butterflies persisted in the same direction of travel. Has anyone else observed this? Is anyone in Minnesota noticing overnight aggregations yet? Any other interpretations?

Wayzata, MN

Latitude: 45 Longitude: -93.5

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