Both chestnut-backed and black-capped chickadees feed together daily at
our feeder in Lake Forest Park (north end of Lake Washington), without any
interspecies aggression. Often they are accompanied by a red-breasted
nuthatch or two, who will sometimes chase a chickadee of either species
off a choice spot on the feeder; but more often, all three species feed
peacefully side by side.

Ter Ellingson
ellingsn at u.washington.edu