Firstly, as soon as you see bird doo on your motor don't ignore it and think i'll clean that off tomorrow, get straight to it lad!
Secondly you only need a quick detailer. Spray on the offending mess and leave for 1 minute - i guarantee it will come off easily and the method of removal will be of no harm whatsoever to your paintwork.
If doo doo is hard to remove its because you've allowed it to bake on which is a no-no for any self respecting car enthusiast!