I moved to Minnesota for a job, but I have my family checking on the perch and reporting back to me.
Our pond is in southcentral PA, and today Mom saw the first ribbons. She could make out 4 ribbons for sure: 2 big ones in the branches on the northeastern side of the dam (shown in attached picture), 1 in the branches on the north/northwest side of the dam, and 1 on the south side near the inlet (shallow end). There's a chance they were laid before today, but this is the first we've seen them.
