They call it “Squirrelzilla.” The gray squirrel rules supreme in a southern Maine homeowner’s yard, scampering up exterior walls and terrorizing the household dog. He is, in a word, chonky. Really, really chonky. Chonky, chunky, big-boned and rotund. That’s how people around the state are describing gray squirrels this season, which seem to be larger than in years past.