Actually, this looks more like the pelvic bone of a bird..... possibly a sea duck........... only know this because I found something similar and someone from NHM kindly identified it from a photo I emailed............ Hope this helps.
Oh I attached a pic of the one I found for comparison.
You're absolutely right, this is a bird pelvis - and very commonly mistaken for a skull! Check out the bird skeleton on this wikipedia article to see what the pelvis looks like http://en.wikipedia.org/wiki/Bird_anatomy
I'm afraid I can't tell you what bird it's from, as that would need quite a specialist in birds.
Hi Luanne, yes there is a guide used as a starting point by us archaeozoo's - Cohen, A. and Serjeantson, D. 1996 A Manual for the Identification of Bird Bones from Archaeological Sites, 2nd ed London
It includes a drawing of a bird skelly labelled and has drawings of the bones of commonly found species (in archaeology) grouped by element, and some useful references at the back. Of course its a bit biased towards the intended audience and even then we always tell students they must use a reference collection but it is a very good starting point. S.