This is a subspecies of Savannah Sparrow that nests on Sable Island, Nova Scotia. They winter in the Canadian Maritimes and along the East Coast (primarily in New England). Note the relatively large size and pale coloration.
The sparrows were well camouflaged among the brown and gold salt marsh vegetation and silvery bits of ice:
We don't get to see "Ipswich Sparrows" in California, so I appreciated this opportunity to watch them for a little while.
Many thanks to Eric and my mom for spotting these sparrows along the shoreline!