I'm glad you decided to take it to a wildlife rescue. I'm just going to leave this quote here for any future folks that might come across this post while looking for answers.
"
The Migratory Bird Treaty Act makes it illegal for anyone to take, possess, import, export, transport, sell, purchase, barter, or offer for sale, purchase, or barter, any migratory bird, or the parts, nests, or eggs of such a bird except under the terms of a valid permit issued pursuant to Federal regulations."
source
https://www.fws.gov/birds/policies-and-regulations/laws-legislations/migratory-bird-treaty-act.php