Magpies.

The local version of the magpie rhyme when I was a kid went:

One for sorrow
Two for joy
Three's a birth
And four's a boy
Five's heaven
Six is Hell
Seven the divil's own sel (devil himself).

These two have taken to visiting the garden each morning and I am afraid they don't bring me joy.  Being Corvids (crows) they are highly intelligent and have worked out how to open the squirrel feeder and pinch monkey nuts.

I haven't yet worked out how to solve the problem other than feed hazel nuts which the squirrels take away and hoard rather than sit and eat them as they do with the monkey nuts (with shells on).