|These guys aren't very mannerly( The picture was taken through a window)|
Brewer's blackbirds nest in the northern U.S. and Western Canada. They have adapted to a variety of habitats and food sources. They usually stay together in flocks of about 100. In the winter they stay in the Southern states and Central America down to the Panama canal.
So in a few more days these birds should reach their winter territories and spend their time marching around yards, parks and open areas. They will probably inundate your feeders like they've done here.