North American Red Squirrel (Tamiasciurus hudsonicus)
These little guys are almost unbearably cute, but they're also accomplished thieves. Unless you buy special (rather pricey) bird feeders, they'll steal all the seeds. Fortunately, they're not too bad most of the year, and most of our birds aren't bothered by them (and we only have two regulars). I once saw a crow chase a red squirrel away when it got too close.They do get very gluttonous in the winter when they're stockpiling, and they'll leave the seed pile with their cheeks stuffed so full their heads look two or three times normal size.
In some parts of Canada, red squirrels have been driven out by invasive grey squirrels, but that hasn't happened here in NS (at least, not yet).
All images © Niko Silvester. Please don't use them without permission. Thanks!