The short answer: no
In Tennessee, keeping native wildlife, including a baby squirrel, rabbit, opossum or a turtle from your yard, requires a permit from the Tennessee Wildlife Resources Agency. Rehabilitating wildlife requires a wildlife rehabilitation permit. There is no exception for good intentions, for "just until it is bigger," or for an animal you have already had for three weeks.
Why the rule exists, beyond the law
The legal answer is the least interesting part. The practical answer is that hand-raised wildlife usually dies, and usually badly.
Nutrition. Cow’s milk, goat’s milk, kitten formula and puppy formula all cause serious harm in most wild babies. Metabolic bone disease from an unbalanced diet is common, permanent and painful.
Habituation. An animal that is comfortable around people does not survive release. It approaches the wrong human, the wrong dog, the wrong road.
Aspiration. More baby animals are killed by well-meaning syringe feeding than by whatever originally happened to them.
Disease. Some of what wildlife carries is transmissible to you and your pets.
Rabies vector species are stricter
Raccoons, skunks, foxes and bats are rabies vector species in Tennessee. The rules around them are tighter, and the consequences of getting it wrong are more serious for the animal, not just for you. A raccoon that has had unprotected contact with a person may be required to be euthanized and tested. There is no quarantine-and-release option in that situation.
Turtles
Tennessee restricts taking native turtles from the wild. If you have found an injured turtle, the important thing is to mark exactly where you found it. Turtles have small, fixed home ranges and one released in the wrong place will spend the rest of its life trying to walk home. Do not put it in water and do not apply heat.
I already have one. Am I in trouble?
In our experience, no, not if you make the call. Rehabbers are not law enforcement, and the agency’s interest is the animal. What gets people in trouble is keeping an animal for months and posting about it, not phoning a rehabber on day two.
Text us at 901-340-6534. We will tell you honestly whether the animal can still be reunited, whether it needs to come in, and what happens next. We have never once been angry with someone for calling.
How to become permitted
If this is a thing you want to do properly, you can. Tennessee needs more rehabbers, and we help people through the process for free. See our page on how to become a wildlife rehabilitator in Tennessee.
Who is answering this
Out of the Woods Wildlife Rescue & Rehab is a TWRA-permitted wildlife rehabilitation nonprofit based in Memphis, serving Shelby County and West Tennessee. This page is general information about Tennessee wildlife rules, not legal advice. TWRA is the authority, and Ask.TWRA@tn.gov will answer questions directly.