crow-island-swallow-migration.avi

Biked into Crow Island from Kochville Rd to witness an overwhelming swarm of swallows, the likes of which I've never seen before. I've calculated the numbers based on the following conditions: There were swallows (Tree dominated) on seven power line lengths between poles with seven lines between poles. I paced the distance between two poles at over 100 yards so conservatively averaged it to 300 feet. There were therefore 2100 feet of seven lines with swallows on them. I then took pictures in a ten ft span and a 25 ft span of the seven lines and counted 85 & 207, respectively. The lines, for the very most part, were equally lined with swallows. Given those numbers, I calculated 17,388 swallows via one photo. (207 swallows per 25' divided to get 8.28 swallows per foot multiplied by 2100 feet (length) to get 17,388. The second set was calculated with 85 swallows divided by ten feet to get 8.5 swallows per foot multiplied by 2100 feet (length) to get 17,850. The two totals averaged came to 17,619.

I'm not wanting to bore you with the calculative details but just to give you an idea how I arrived at these estimations. Keep in mind, too, that the lines drooped with their cumulative weight (making the actual distance between poles greater than my paced off 100 yards) along with many that were in trees and many that were flying. The total could have exceeded 20,000 swallows. Needless to say, it was quite a migratory encounter!

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Science & Technology

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• MI