Probably a window collision, seems dead
I think it's a male mallard in eclipse plumage based on photos online, but I'm not sure.
Female uploaded separately
Extremely noisy. Making a ton of different distinct noises. Grabbed a twig and shook it until it broke off the tree, then flew to another tree with it. I didn't see any nest.
Blending in with the Brants
beak seemed rather blue
Found dead on the trail.