Natural scents in general are considered to be safe, and that includes things like boiling cinnamon sticks in a pot on the stove to put a pleasant scent in the air.
This next part wasn't part of the original question but I want to mention it to make sure that nobody who's reading this gets the wrong idea. It's NOT safe to use a natural scent that's been concentrated into a form that's much more intense than you would find in nature. I'm talking about essential oils here - they may come from a natural source, but if it comes in a bottle it's obviously not in its original form any more and can be dangerous. There are people out there pushing essential oils for birds but it's not a good idea. If you're lucky or careful you can get away with it, but if you make a mistake it can kill your feathered friends. http://www.littlefeatheredbuddies.co...matherapy.html