Lake Merritt is home to hundreds of Canadian geese that have made Oakland their permanent residence. Migratory by nature, these waterfowl have decided there's no reason to leave. Flying south for warmer weather and abundant food just isn't necessary as the weather in Oakland is mild year 'round and the good citizens completely ignore the signs not to feed them.
Oakland's homeless are a lot like the geese. They've just decided to stay because the weather is nice and people feed them. I only wish they wouldn't pee on the sidewalk.