Well, lost a duckling this evening.
We had them out for their first swim this afternoon, brought them back in - everyone was fine. Had a little kale treat about an hour later, still fine. They already have us trained - when they wake up from their nap; they make a racket. They expect someone to talk to them while they eat. They stand & chirp and look outside the box until someone joins them. About an hour ago they got up chirping as usual, the wife went to say hello and called me over. One was barely chirping and wasn't up with the others. Called me over and I picked her up. She was limp in my hands & I did a quick vent & throat check. Seemed ok. Laid her in the box we use when cleaning the brooder. Quick convulsion & was dead. Other five seem normal, watching them close. Very sad.
No clue as to what happened, we had discussed losing babies, still heartbreaking.