|MadSci Network: General Biology|
Most birds get eaten and that is why you do not see them dead that often. Migration also takes a heavy toll and these animals may die in places far from where you normally see them.
The question about bats is the most interesting and I do not have a full answer for you. Bats do give birth hanging upside down because that is the only way they can hang. I can tell you that when bats land on a tree or a ledge, they finish their landing manoevre in an upside-down position. Bats have a special arrangement of tendons that allows them to hang naturally in this position. (See this answer about bats hanging upside down). The pup that is born is quite large compared to the adult and probably quickly assumes a hanging position. Whether the mother uses her arms in the birthing process I am not sure.
All cats in general can purr. Purring is important in communication between a mother and her kittens. It is thought that purring provides a quiet way to communicate without alerting potential predators.
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