i recall hearing ( no confirmation ) of a pelican going through the windscreen of a 172 in florida...but in over 3000 hours i have had only one strike ( to the wing ) of a pa38 tomahawk with no damage resulting....
as christimson said you have probably a better chance of winning the lottery than having a serious birdstrike in you flying career ( if you are flying light aircraft )...but then the risks might be greater if for instance you fly in an area of intense bird activity...and depending on what part of the world you are flying in...many countries have large birds that fly at low altitudes and obviously the size of the bird ( not just the strike location ) is relevant..
i recall reading many years ago of an eagle ( i think ) that penetrated the cockpit of a 727...
like many things in life...its often a matter of fate and timing...
the dean.