This evening while paddleboarding on Boulder Reservoir, I saw two terns out with the gulls on the floating docks. They didn't stay near for long, but were noticeably smaller than the gulls and had black caps. Bills weren't noticeably orange. As they flew away towards the northeast part of the res, one stopped to hover and then dive in the water. Both were silent the whole time.
Wish I had my binoculars out there (or was a faster paddler)!
Good birding,
Laura Steadman
Boulder