The Canada goose, or "Honker" for its characteristic call, is the largest of geese and should be pretty familiar if you've ever been to a park or a golf course. Honkers have a thin, long black head with a white stripe under their bill which gives them away. They have a large gray body and make a characteristic "honk" that can be heard miles away.
They're less common on most of the California refuges, but often show up at Llano Seco out of the blue. Be ready for them!