Depending on the height and weight of the falling creature, and its aerodynamical properties, there is no rule in game to define the damage for falling tiny creatures. By the given rules a humanoid falls 500 feet per round and takes 1d6 bludgeoning damage per fallen 10 feet up to 20d6 (Feather Fall 60 ft./rd.). By this article (https://perryponders.com/2015/07/16/ants-fall-from-any-height-without-dying/) the terminal velocity of a human is around 1,056 feet per round. A cat (528 ft./rd.), mice (147.48 ft./rd.), or an ant (34.32 ft./rd.) have even smaller terminal velocities, all surviving an almost unlimited falling height in air and by earth gravity. What will be the damage to tiny creatures, when they fall and hit the ground in Toril? Would a flying familiar like hawk, raven, bat, or owl wake up or die (return to its dimension) when it hits the ground, if it falls prone or were put asleep in flight? This seems also be relevant for the Polymorph spell and the Druid Wild Shape form, used to "parachute."