ATM there is a pair and a juvenile visiting my garden daily. They are in competition with a young Crow and 5 Jays for the peanuts in shells. Up to now the Jays are getting the most food, but the Crow has made itself at home and waits on the fence for the nuts to be thrown out.
Obviously all the birds are wary of the Crow but the Squirrels just charge through the garden to get to the nuts. The Crow has started to jump sideways, but it's becoming more bold.
The Jays are wary of the Magpies, but they out manoeuvre them often, The Jays are so acrobatic (or should that be aerobatic), they can spin on a sixpence. They also bounce off the fence and the wall.
The only food the Magpies seem to get unchallenged is bread that I throw in the bird baths. They will ignore dry bread but seem to love it soaking wet.
Magpies do get a bad press, the Jays seem to be ignored, even though they are just as guilty.
It's very hectic in my garden ATM, because of this the Sparrowhawks are visiting more than usual. If you look at my thread
http://www.birdforum.net/showthread.php?t=122165 you'll see some new pictures of a female Sparrowhawk with a Squirrel, not eating it, just puffing herself up to warn it off.