Date: 09/25/2021

Number: 100

Tons of roosts in the tall oak trees and tons fluttering around. Easily 100+

[Additional information contributed by observer, added by Journey North, 09/29/21]:

I have no idea when it formed - it’s a historic NPS site that we happened to visit on Saturday evening 9/25/21 around 6:45pm local time. There were lots of wildflowers in a nearby prairie, but not much right where they were roosting. Some purple iron weed I believe, and possibly some golden rod, but I’m not 100% sure.

It was a cool day and cool evening. We saw them at dusk. High for the day was in the 70s, low in the high 40s. See the weather picture attached with data from that location on 9/25/21.

Roosting in mature, tall oak trees. It is an area that is a relative high point for miles with prairie and a dam nearby, and then with the tall oak trees, it is a high point. I didn’t notice wind direction, but they seemed to be roosting in areas where the sun was still shining on the leaves at dusk. Wind 7 mph from west.

I counted the ones I could see in one of at least 10 trees… at least 60, but there were constantly ones fluttering around looking for a landing place and the trees were so tall and it was dark enough that I could only see several bunches, but I’m certain there were many, many more. I have never seen so many at once.

Dayton, OH

Latitude: 39.8 Longitude: -84.1

Observed by: Jenna
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