Unfortunately even things in the back garden seem to go here. When we put rubbish out people have been known to look in the bags (!!) too to see what it was and anything 'free to a good home' put on the front is gone by the end of the day so a decoration wouldn't last long in our front garden sadly.
If it's possible to secure them I would - it'd be cheaper than replacing them if they get broken or stolen. Unfortunately you can't have anything anymore!