A just visible broken eye-ring.
Elsewhere, a yolk-filled egg on the ground, cracked open. Some tiny insects had drowned in the yoke.
Yet again elsewhere, an inch of life that didn’t.
Grubstake… worm and something else.
“Terrifying are the attent sleek thrushes on the lawn” writes Ted Hughes from the invertebrate’s light-sensor view.
Backyard and Beyond 
pretty robin’s egg blue.
I have been looking at robins’ eye arcs this spring and discovered they are widely varied within the species, but also may not matchon the same bird! Some arcs nearly become a complete ring while others are distinctly separated from each other. Some have a long tab which noticeably protrudes outside the implied circle. Others have a tab that is barely noticeable. There is much individual variation of this plumage on this species.
I think you’ll find this the case with most birds if seen well enough, and long enough… hard to do with warblers and other songsters up in the trees.
No shortage of Robin’s. Fortunately a few accidents isn’t a hardship.