Date: 09/06/2014

Number: 1500

There is a roosting site on my mom and dad's farm East of Yankton. The Monarchs are grouping mostly in Mulberry trees but also in Ash and Elm. They are clustering in large groups of 50 to a 100 with over 1,500 roosting in multiple trees (on 9/6/14). Once the sun hits them in the morning they start to open their wings and flutter around but mostly they seem to be resting.

The butterflies started arriving on Thursday the 4th of September. Mom noticed them after work, around 4:30PM. More arrived on the 5th and the maximum number arrived on the 6th with the total count that day being around 1500 butterflies.

It was a windy day on the 7th and my mom thought they had gone but they had retreated to the grove of trees where there was more of a wind break. The Observer newspaper came out and took pictures.

Here's a summary of evening counts:

9/4: At least 100 monarchs
9/5: 400-500
9/6: 1000-1500
9/7: 1000-1500 they moved out of the wind to the grove of trees.
9/8: 500
9/9: 200-300
9/10: 200
9/11: 50 they are not moving due to the cold front that has come through.
9/12 500

Update September 13
I came out to the farm today (9/13/14). There is a 25 mph south wind and there are at least 500 Monarchs on the edge of the grove. It got down below freezing last night (9/12/14). At 10:30 AM, the butterflies that were warmed by the morning sun were flying around and the ones in the shade were still hanging in the trees.

Yankton, SD

Latitude: 42.9 Longitude: -97.5

Observed by: Tanner
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