If you found a baby animal that may have fallen out of its nest it is best to try to reunite the animal with the mom. Cedar Run Wildlife Refuge provides great information and care for orphaned wildlife. Here is a link to all the information you should need to know if you happen to find a baby animal.
Rabbits: If the young rabbits are the size of a tennis ball (4-5 inches) or bigger and their ears are standing up, they are ready to be on their own. Baby rabbits grow up in about 4 weeks. They are still small when they are on their own, but they can survive. Mother rabbits are away from their nest most of the time. They only come back twice a day, in the morning and evening. Just because you don’t see the mother doesn’t mean she’s not coming back. Even if there was a disturbance, the mother will most likely come back. Place some string in a star-shaped pattern over the nest and wait 12-24 hours. If the string does not look disturbed after this time, the babies are abandoned and need to be brought to a rehabilitation center. To keep dogs from disturbing a nest, either keep the dogs inside unless supervised or place a wheelbarrow or box upside down over the nest. Make sure the mother can still slide underneath to get to the nest.
Squirrels: If not injured: make sure the squirrel is warm and put the squirrel in a basket or container with holes in the bottom and hang in a tree nearby where the squirrel was found (as high as can be reached). Squirrels make multiple nests, so the mother will most likely take the squirrel to new nest.
Fawns: Fawns are often left alone by their mother for long periods of time. Reason that you may need to call in a fawn: the fawn is injured, there is a dead doe near, the fawn looks emaciated, weak, or disoriented. If you find an injured adult deer please contact your local police department.
Songbirds: If not injured and not fully-feathered (nestling): put the bird in a basket or container with holes in the bottom and hang in tree nearby where the bird was found. Observe from a distance. It is a myth that if you touch a baby bird the mother won’t come back for it. If the parents are coming to the makeshift nest: the bird is fine. If not injured and fully-feathered (fledgling): place the bird in shrubs/ bushes nearby where it was found. The parents will still come back to check on the bird and feed it. The bird is learning to find food on its own and flying over the next 1-2 weeks.