Summary:
The four lb bird delivers 47 times the impact energy of the bullet!
The Canada Goose delivers 176 times the impact energy of the bullet!
True, but the energy from the bullet is much more concentrated. The contact area for a bullet on the screen would be what? A few square mm?
However as the bird goes splat, its energy is spread out over a
much larger area. You need to work out joules/mm^2 (or equivalent).
Put it like this - If I had the choice of standing behind a windshield facing either a bullet or a bird... I'd choose the bird. But as we've heard here, the windshields are pretty strong, so reckon I'd be safe anyway!!