Devastated! My duck just died... Please help!

[certze]

Our five week-old duck Twinkle just died.

I can't begin to describe how sad I am. We had never hatched ducks before and Twinkle was the lone survivor in a failed batch of 10 eggs in our incubator. She imprinted on me and I grew extremely attached to her. She was such a lovely wee creature, with such a sweet personality. We knew she shouldn't be alone, so in a much more successful attempt we incubated another 8 eggs which hatched (100% this time to our surprise). The wee ones instantly adopted Twinkle as their mum, and though it took longer for Twinkle to tolerate them, by now they were all a flock lodged happily together in a room in our house with access to a very safe balcony. Only Twinkle had a daily waddle through the garden with me and had started swimming in the pond (we just finished and filled it up a few days ago). She absolutely loved her daily excursions and all seemed fine until tonight after her pond-time she started spitting out gooey bubbly clear stuff with bits of what seemed like mud and pond muck... Within a few minutes something seemed odd, but I just thought she was a bit tired... She then had a very runny dark red poo, which looked like one she produced once when I gave her some tomato (no tomato was given to her today). She wasn't coming when I called her (she would usually come for cuddles) so I went to see her and I realised there was something wrong in her posture... She was hunched over, her legs and wings spread apart... She hadn't done her usual obsessive preening or her rinse in her clean bath. I could tell something was wrong by now, so I started getting her ready to go to the vet, but as soon as I picked her up I noticed her legs and neck we're going limp and within minutes she was gone. I am truly devastated. I can't believe she's gone.
However, as sad as I am, I've got the other 8 wee ones to look after now, and NEED to know whether what happened to Twinkle is contagious or could have been prevented.
Please, if anyone could shed some light I'd really appreciate your help.
Here's Twinkle just a few days ago:

Here's the pond:

Here she is with the wee ones:

 

[Amiga]

It sounds first off like she got into something poisonous. Very sad for your loss. The only way to be sure is a necropsy - you might want to contact a vet and see how you might get that done. The body must be kept refrigerated. I don't mean to sound callous - but it is a detail you need to have right away to make your decision.

So, was the water icky? Might there have been a dead animal nearby? Rotting vegetation? Did someone put something outside she could have poisoned herself with?

I need to be away from the computer the rest of the evening. . . I will check back when I can.