Last two photos in the most recent series are of an adult, first ones are of a juvenile. And, you can't gauge the weight of a chick in a photo, the birds puff up and slick down their feathers so you can't really tell the condition of the bird ... so basically, don't fret yet.
If the bird looks rough or haggard - like s/he went through a blender backward and had tidied up but you can still tell a blender was involved - that's another story.
And since there is obviously still an adult in the area (the 7pm photos are evidence of that), the chick won't be starving ...
Help any?
Thanks, TPC! The concern wasn't actually for the juvies here - people were concerned about one of the Lincoln chicks who looked somewhat thin, and that's why I made a reference to the first pic here. I did label the pics of a parent as such. Zeus and Hera stay in the area all year - they don't migrate.