Awww! I love baby Runners! Yours are so adorable.
I have found that ducklings do indeed grow very quickly. I am more used to chicks taking a while to become chickens. It even seemed like my ducks were just babies and *snap* they were laying eggs! I know it was still 6 months just like my chickens but still, those ducks shoot right up. Must be all the water!
They do look like they're smiling with those bright eyes and beautiful chocolate colors. Mine grew up fast too. Good thing those babies are so messy it keeps me from getting more. Makes me happy when they're a little bigger.