Here is a photo of a little guy we found across the street. It was chewing on the remains of a little bird that had fallen out of its nest. It was right on the curb and I was concerned about it getting run over. My son and I put it in a box and took it to a ditch area behind our house. Usually possums this small are with their mothers. This little guy appeared weak and the wound on its head is very apparent. The heart in me wanted to take him in and get him up to strength. What to do? During this season, a lot of little birds will be falling from the trees. There is really nothing you can do for them. A young bird, yet to reach flight, is extremely vulnerable to pet cats and dogs. Feeding and caging them from your own pet, is impossible. Birds, possums, same problem.
I regret that I didn't leave that little fellow with some dog food or a can of tuna. However, my son and I did remove him from the dangers of man (cars). We took positive action. We did leave him in nature in a more secure location than when we found him. Nature has already been cruel.
We did our part. There is a philosophical lesson here somewhere.