And What About Siskins?

With the irruption of Red Breasted Nuthatches into the Piedmont this winter, my thoughts turned quickly to the prospect for other irregular winter backyard birds.  The top prospect would be the Pine Siskin.  We've seen them a bit more often than the RBNs in recent years, with my last sighting in February 2011.  The siskins are certainly interesting and entertaining, although they are highly aggressive toward other feeder birds and eat like there's no tomorrow!  So perhaps I need to restrain the wonder on a budgetary basis?  I am watching intently to see if anything new comes along in the coming weeks.  And if not siskins, what?