Dead baby bird

No, not the shit band from the 90's with their terribly annoying song about some idiot being georgeous, but a realy life dead baby bird.

Saw it earlier by the pavement outside the office. I was trying to work out how it died, like a ornithological Silent Witness or something!

The evidence was thus:

Small bird nestled against curb
Looked fresh
Had a head wound but no other visible damage
Head wound looked like it was caused by penetration
It was almost directly under the office building, which is quite high

So I thought of three possible death scenarios:

1) Bird in nest atop of office. Enemy bird pecked its head in and then either took the bird (to eat or something) and dropped it, or bird fell out its nest after the head pecking. It is also possible a rival male killed it as it wasn't his off spring, or the mother did as she had too many chicks to feed. Or, my favourate but remotest possibility, that it sustained the head peck in a mid-air bird to bird dog fight. I like to thing birds have pecking fights mid air, but I doubt it.
2) Bird was on ground and hit by a car, which scouted it to the side of the road at the same time.
3) Bird flew into office window and fell to ground.

I think 1 is the best case scenario. I am no expect but 2 seems unlikely as the precise nature of the head wound doesn't hold with a car collision. I would expect more mess if a car ran it over. 3 is possible, but again when I have seen this before, the bird doesn't usually have a laseration, its just been brained by flying into a window and hitting the floor.

So 1 it is, I think it was subject to an in nest head pecking, but I am still working to proove this.