Here we have Barn Swallows flocking up prior to migration. This was along a country road in South Dakota. Most of the birds chose the lower wire. Every time they flushed and returned, it was the lower of the two wires. Why is that?
Birds on wires: why favor the lower?
Barn Swallows in migration
September 19, 2015 at 2:09AM
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jim williams
It’s too soon to tell how much the immigration crackdown is to blame.
