Juvenile Red-winged Blackbird

Photographed this small bird on 28 August 2014, in southern Alberta, quite a distance east of Waterton Lakes National Park. It was hanging out at a campground with a number of Brewer's Blackbirds in a patch of small trees/shrubs right next to a river, but I can't remember if we saw any adult Red-winged Blackbirds or not. If anyone can either confirm or correct the ID, I would really appreciate it - thanks!