By 'mating plumage' I mean those distinctive 'antennae' draped back down their necks.
We see the grey heron flapping east and west, to and from, Farmoor on a regular basis but to see a pair of white egrets was a lovely surprise. At the same location, same day, same hide, the wife noticed a darting Kingfisher. Me, I was too busy looking up Tufted Duck on the hide's charts, the striking black and white one.