Granted, the Census Bureau publishes lots of fun data, but it's all so anthropocentric. What about the nonhuman U.S. population? Happily, a report from the American Pet Products Manufacturers Association has come our way with several hundred pages of data on our canine, feline, piscine, avian and reptilian friends. (Nor are rodents, pigs and crustaceans neglected.) Dogs inhabit 39 percent of U.S. homes, cats 34 percent, freshwater fish 12 percent, birds 7 percent, miscellaneous "small animals" (including gerbils and hermit crabs) 5 percent and reptiles 4 percent. One measure of the devotion these creatures inspire: "Nearly 5 percent of total pet owners said they would purchase a casket upon the death of their pet." But why wait till they're dead to buy them a treat? "Except for reptiles and fish, more than 60 percent of pet owners in all other categories said they buy gifts for their pets." While these are often given in the absence of a special occasion, 28 percent of bird owners give their pet a Christmas gift, 26 percent of dog owners give Fido a birthday treat, 2 percent of reptile owners give a present "when we go on vacation" and 1 percent of fish owners give the gilled ones a little something on Valentine's Day. (Don't worry: I couldn't make this stuff up if I tried.) One last info-tidbit: Turtles/tortoises and snakes have gained ground, while iguanas and lizards have dwindled.