If you have not figured out what it was yet, it's a raven. The hard packed sand did not show obvious (to my untrained eye) impressions from the feet, but the the back claw left long scratch marks as it trailed behind. I have not noticed the claw scratches before. I think the churned up sand was from a raven poking its beak in the sand. I am not sure why the raven might have done that, as this patch of sand does not seem to have much evidence of shellfish (it's in the high tidal zone).
Location: Halibut Point Recreation Area, Sitka, Alaska