Bird watching against the moon

This evening I was playing around with my spotting scope taking photos of the moon with my Samsung Galaxy S4 phone. As I was focusing the scope before mounting the phone/camera on it, I was surprised to see a flock of large birds flying east to west across the face of the moon. I didn't catch them in a photograph, but I immediately followed them with the scope and identified them easily as medium- to large-size gulls. They were so high I could not see them with the unaided eye. I'm guessing they might be California Gulls heading to the coast from somewhere inland, probably east of the Cascades. Apparently the breeding season is over for them.
(You can click on the photo for an enlarged view of the moon.)