Monday: April 22nd: My God, the swirling swarms of swallows! There were several stretches Saturday where the swallows were intensely thick, coursing above the river. The thickest places seemed where the river flowed wide, shallow and choppy. I hypothesized thin water allowed maximum sunlight and photosynthesis on the submerged rocks and the chop would stir in maximum dissolved oxygen so the area would be at a biological productivity maximum. Some sort of small insect must have been emerging/seething out of the river but I never saw them because the swallows were so thick. I could hear the swallow beaks snapping shut and so could hear which areas around me had the most insects. One swarm stretched out for more than 15 minutes, which was probably almost two miles of thickly swirling swallows (10,000-15,000 birds).
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