Yes, blown away!
...Or wait... is my English actually correct here?
In any case, Indian Runners are particularly prone to be carried off by the wind...
...and I had one that had even learned to fly because of that, and was thus happy to fly over the fence during mating season if I separated him from his friends...!
(At the time, his son himself had then even learned to fly by copying him...!! Boy was a smart boy, huh...?)
Soooooo...
...I would just :
• keep letting the ducks have access to their food at night;
• mix their pellets with wheat - 50/50 is a good ratio, but if you prefer, you can put about 65/70 % pellets for 30/45 % wheat too;
• be careful to not give them too much rice to eat, raw meat, or salt(ed food).
...Not a problem, don't worry...!!
They do eat it, and they love it...!
If you don't see the tray with the crushed eggshells emptying, it could only mean two things :
1 • that your ducks do eat them, but you just don't notice it because you don't have enough ducks to empty the tray quickly enough;
2 • that they don't eat them, because they don't like the taste of crushed eggshells - and yes, it is possible : ducks are pretty capricious in my experience, and won't eat what they don't like OR are not used to be fed with...
For now, I would not insist, and would replace the crushed eggshells with Oyster Shell grit instead.
► I personally can see the Oyster Shell grit that I give to my ducks disappear from the feeders by the days... but I have A LOT of ducks, so it is only natural.
(Though when I had only 4 ducks, they didn't appear to actually eat a lot of it...!)
► For the record, I have noticed that duck hens start eating significantly more Oyster Shell grit not long before they lay their first egg.
