Observed hood, square tail, head shape
Impression was Cooper's from non-labored flight style, but it was only a quick look. Not sure these photos are good enough for ID.
One of a pair flying around together, one banded, this one not banded.
Female likely, slightly bigger than a magpie.
We could see these grebes rushing and clearly hear their distinctive calls from the ridge. I counted 130 birds, but could not distinguish to species.