Baby animals are so cute I am sad when I eat them. It's fun to watch them play. What about the birds and the bees? Do hatchling insects, ornithoids, and reptilians play?
Fireball, Hathaway Pines, CA (a PB escapee)
We've sent the elves out to see if they can find a butterfly with an Xbox or a June bug with a pool cue. Couldn't scare up any info on playing bugs. The science guys might say this is due to their tiny life expectancies and tinier brains. And they can say this with some certainty because play behavior is a hot biological topic. Not just studies of apes and man and familiars like cats and dogs, but life forms like birds, turtles, lizards, kangaroos, and octopuses. There's a whole academic association for the study of play (called, uh, the Association for the Study of Play), but they're in Florida and probably specialize in primate behavior during spring break.
Unfortunately, Fireball, a lot of questions still exist about the definition, evolution, and purpose of play; but at least we can give you examples of the animals that science has annoyed in pursuit of the answers. Your ornithoid things are represented best by ravens. Ravens are notably curious and learn fast. Juvenile birds are particularly fond of manipulating new objects in their environment, nipping at domesticated animals, doing aerobatics, and generally acting up spontaneously for no obvious reason in that particular environmental context. And having fun doing it, since they keep on doing it. The theory goes that play is an extension of general exploratory behavior and helps birds, etc., become familiar with their territories and learn what to fear/eat and what not to fear/eat. One noted scientist opines that play behavior also is an outlet for pent-up energy.
The octopus is the only invertebrate that has been studied for what the science guy defined as "play" behavior. The experiment involved six octopuses, an empty plastic water bottle tethered to a rock so it bobbed under the surface, and a Lego piece that was buoyant but didn't actually float. After the octopuses were through manipulating the toys and trying to open them as they would a tasty clam, they began to play with them. Push-pull games with the water bottle, towing it around in circles, passing the Lego piece from arm to arm to arm to arm to arm.
One scientist wanted to study the prehistoric origins of play behavior. Figuring that turtle-y things have been around for at least 40 million years, he thought they'd make good subjects to find play in our genetic roots. Dang if he didn't see young turtles nipping at their pals, manipulating objects, and generally behaving in a playful manner.
The Alices were lucky enough to watch several generations of kit foxes grow up in a back-yard canyon. Talk about a playful pile of furry things. Today's hip young experimenter would say the kits (and your puppies and kitties) engage in group play fighting not to sharpen their physical predatory skills but to condition their brains in coordination and to learn to judge what the other guy's thinking. The old theory that lion cub play teaches them how to later attack antelopes has been chucked into the biological Dumpster, apparently.