We have three blue jays who regularly come to
Carleen's kitchen window hopper-like feeder.
I can tell the three apart from the pattern of
white in their primary wings. "Mostly white" is
dominant, i.e., chases away, "Some white" and
"Little white." Some and Little seem to get
along just fine.
If one has the opportunity nearly all birds can be
separated individually like this, at least on
the short term.
Good birding, Larry H.