Do my ducklings have an impacted crop?

[annabanana017]

I didn't actually know what the extra fat at the front was until now, so now I'm worried that my ducklings have an impacted crop. I don't even fully understand the concept of the crop or if it's bad if it is big. Can someone tell me if it looks okay or normal, or should I be worried?

 

[sourland]

Just looks as if they are eating well.