The first picture is of the carcass of a Laysan Albatross chick. It’s obvious what killed the chick: the fact that the only thing in its stomach was garbage.
Albatrosses fly hundreds, sometimes thousands of miles in search of food for their chicks. They look for squid and fish eggs floating on the surface of the water. Unfortunately, plastic floats, and Laysan albatross are particularly attracted to it. They eat it, mistaking if for food, then they fly back to the nest and feed bottle caps, lighters, fishing lures and other pieces of plastic to their young. The chicks starve to death, with stomachs full of plastic.
The second picture is of the contents of a different chick that was found to have greater than a half pound of plastic in its stomach.