NATURE: "PETS: WILD AT HEART"
PBS, 8:00 p.m. ET
Part 1 of 2. No animals were harmed in the making of this very friendly two-part Nature documentary. It’s a look at the “private lives” of domesticated animals, from cats and dogs to horses and hamsters. Tonight’s Part 1 is called Playful Creatures, and explains the unspoken canine rules at a neighborhood dog park, visits an amazingly verbal parakeet named Disco, and tosses out one fun fact after another. Such as: all golden hamsters come from the same family, from the previous century, that lived in Syria. And: when kittens feed from their mother, each has a designated nipple to which it, and it alone, returns for each meal. Check local listings.