They would say that the cruelty has to have been inflicted by humans! It would be best, I saw with hindsight, to have said that I had witnessed a despicable, unidentified person inflict the injuries. My daughter incidentally works full-time at a charitable trust, wildlife centre, based in the Cotswolds, and she deals with injured wild animals daily. You could check if something similar exists in your area. (She told me Jethro Tull came in recently with a baby owl, took off their hands a couple of hedgehogs for his garden, and was so impressed, he gave them a cheque for £500. !)