Age: The flight feathers, all-white tail and body feathers point to an adult-type, large white-headed gull (LWHG).
Identification: Our October bird is a black-backed gull with pink legs. In North America, we have two regularly occurring black-backeds with pink legs: Western and Great Black-backed, but this individual is neither.
Structurally, both Western and Great Black-backed Gull have noticeably different bills than what's seen here. Western typically shows a brighter yellow bill with a wider gonys angle - a bulbous-tipped bill, if you will. Great Black-backed's bill is much more stout and thick - a strong bill all throughout with a blunt tip.
Adult Western. Note the bulbous-tip and mustard-yellow orbital ring.
San Luis Obispo County, California. January.
Adult Great Black-backed. The gonys is swollen and the bill is thick throughout.
Huron County, Ohio. November.
Here's a cropped image of this gull's right wingtip:
A species that's generally increasing in North America, particularly on the Great Lakes in winter, this month's Slaty-backed Gull was photographed in Lake County, Illinois. February.