Id for carcass. Gulls brought something near the glass, but they couldn't possibly mutilate bird found there this fast, so this must be some piece of bigger animal or older leftover instead? It was soon swallowed as whole anyway. So: recent glass collision victim or something else?

Gull came around meauwing, next time I looked behind my back it was taking from elm seeds I think juvenile house sparrow and digesting it. It was already early evening and none of house sparrows were at open ground, neither they were alarming the event. So even though place would suspect it predated unaware young sparrow feeding on elm seeds, but I guess more likely there has been earlier car collision instead.

EDIT: I'm inclined to think gull somehow predated sparrow from its flying path.

The mulch was put down yesterday and I didn't see it this morning, so I assume it fell from its nest sometime between 9am and 6pm.

Near the pine tree that seems to be dominated by house sparrows, but I haven't spent much time looking for nests.

Scavenged by but unlikely brought here by crow. Maybe goshawk prey instead? There was unlikely fieldfare flyby and call last night two hours after dark.

By closer look, this was surprisingly small: headless body length roughly 10 cm, longest wing feather 15 cm.