I have 3 week old chicks that I rescued from the wild. I live in Hawaii and there is obviously a lot of sand here. As they're getting older, I'm starting to think about giving them treats and also what they'll be eating as they get older and are weaned off chick starter. Can I bring some sand home from the beach for them to eat as grit? or anything else from around the yard? The wild chickens here seem to manage just fine. Is there any danger in that that I might be overlooking?