I think the Dipper does look rather rotund, but I think the Waxwing looks pretty normal...

It may well be that Dan Zetterstrom drew both species in winter originally, hence their perceived plump appearance? Either way, for my money he's pretty much spot on.

Is it just me or is the adult Dipper drawing on p273 of the 2nd Edition Collins Bird Guide unduly plump? The adult male Waxwing on the same page seems equally so. Or is it just my poor eyesight out in the field?