Hi there I have some domestic ducks and I also have started rescuing wild (mallard) ducks. I live on a rural property where there are load of wild ducks. I live in New Zealand where it is currently mid winter. We had a really warm autumn this year and as a result a few of the local wild ducks have started hatching out ducklings. I have been catching the ones I can and raising the ducklings (alongside the mother). The weather has now become cold with frosts at night and the ducklings arent able to survive it in the wild, all the ones I have been unable to catch have died at under a week old. I have so far since late autumn, had 1 lot of 12 who are now juvenille adults and doing great. After them came 4 ducklings who had some health problems along the way but on the whole are doing well. Mext up was a clutch of 13. One of these died a few nights in, I found it in the indoor house and assumed it must have been smothered or trampled. Then there was a lone duckling that had gotten cold and coldnt keep up with its sibling and mother, which I picked up, took inside and warmed up, I wasnt able to find the mother and one other sibling to take them in. Tha duckling I put with some older ones who adopted it and it is doing great. Then late last week a duck showed up with 13 ducklings which were only a few days old. I got them into a house and run. All seemed fine. That first night there was a hard frost, the next morning all seemed fine. I let them out into the run. I had left them with a small pool assuming the ducklings would,be waterproofed by their mum. They had been in the pool the day before and were fine. About 15 mins after letting them out I went to check on them and found all the ducklins sayurated, clearly not waterproof. So I put the lot back inside under the light straight away. One was clearly showing signs of being too cold, and I took it indoors and warmed it up with warm blankets and a hottie in a box with an electric blanket around it. Another started showing the same thing, but not as bad, and I brought it in and warmed it too. Once both had warmed up and were starting to wander about I returned them to mum and left the lot of them under the light for a few hrs until the outdoor temperatures had warmed up. I removed the pool straight away. Later that afternoon, all of them were outside in a run with mum, running about, generally bei ducklings. Half an hr later i counted them and one was missing. A frantic search ensued, of the house, run etc, then the surrounding area. Then I returned to the run and found a dead duckling near the entrance to the housing part. The dead duckling had an indentation on its head and I was horrified to think that maybe I had stood on it and not noticed. I spent that evening berating myself for my thoughtlessness. On The next day I had to go out to do work flr most the day. I left the mother duckand 12 ducklings all seemingly fine in a small enclosed run beside their house, and left the light on in the house. When I got back that afternoon, I found a dead duckling inside the cage they were in only a foot or so from the rest of them. The dead duckling had no sign of injury. I assumed it must have somehow gotten too cold and not been able to walk to the mother or maybe been stood on or sat on and smothered. The remaining 11 ducklings I checked out individually and all were alive, and seemed perfectly healthy. They went out into the larger run, were exploring and generally being ducklings. Then a few minutes later one seemed to trip over and tipped onto its back. And it was flailing its legs but didnt seem to be able to right itself. i went in and picked it up intending to simply put it up the right way. But moticed immediately the duckling didnt feel right. It felt flaccid and floppy and its head was doing this nodding wobbling un and down thing. At first I thought it maybe was just too cold, as i have seen them get floppy and uncoordinated when too cold. I took it straight indoors to warm it, but by the time I put it down on a warm towel it was unable to even sit and was flopping over on its side and its head was starting to arch upward. I kept warming it and syringed water, then sugar water into its beak, which it seemed to swallow a little of. However it kept getting more floppy then seemed to actually stiffen up, and take the position they are normally found dead in. I thought it had died a couple of times before it actually did die, till it moved its head a little. It seemed as though it was progressively unable to move any of its limbs, then neck and head. It seemed to want to swallow water but was unable to do so, and shortly after it died. From seeming to be perfectly healthy, normal energy, moving about, eating and foraging and so on like a normal duckling, it went downhill amazingly fast.one minute it was running about, then It trips and suddenly it cant control its legs or balance any more, and from there, rapid deterioration to death. So that was 3 ducklings died in 2 days. Ten left There was no time to get it to a vet. After this I was pretty paranoid checking on them all the time. All seemed find, and on The following day I was relieved to put them to bed with 10 ducklings alive and looking fine. On The day after that they were all fine and again i was happy to put 10 ducklings in to bed that night. I checked on them several times before I went to bed and they all seemed fine. Being indoors under a light, with water bowl they couldnt get into and a flat low tray with food in it, I didnt expect to have any of them die in the night But in the morning this morning I found a dead duckling in their food container. The container is low wide and flat, and all the ducklings can easily get in and out of it. This one was covered in food and cold. I can only assume whatever mysterious illness struck the last one in my presence, hit this next one while it was eating some food. I have spent hours online researching to try and find out what happened, but the only things that fit the way the duckling i saw die went, were botulism and a disease called viral duck hepatitus which only affects young ducklings. Botulism is unlikely as its usually contracted from carcasses or maggots, neither of which the ducklings had contact with. Plus outbreaks normally occur in warm weather, and the first signs are apparently dead ducks. None of the adult wild ducks have died that I can tell and all are in good health. And the viral hepatitis while it is apparently more likely in colder weather, and hits only young ducklings, apparently is 100% mortality rate in a flutch of young ducklings, so if it were that It would be unlikely any were alive now. I contacted a vet who have avian experience, but they only said they coudlnt see anything in the care I was giving that was wrong, and that in the wild ducks have large clutches and lose a lot of them and this was normal. But to me its not. In the wild they lose a lot of ducklings. But not because they drop dead for no reason. They die due to predation, or getting too cold, getting lost from the mother and then getting eaten or too cold, starvation, and so on. They die for reasons, ive never heard of it being normal for them to just die out of the blue with no cause. And all of those things that kill them in the wild, thought I was removing or at least drastically lessoning the risk of, by providing food, shelter warmth, security from predators, and ensuring they couldn't wander off and get left behind to fend for themselves etc. Aside from the first duckling none have had any signs of injury no blood, or marks on their skin anywhere. And the first one possibly got stood on after it died. So it wasn't a predator, or there would have been injury or simply no duckling to find. It is unlikely to have been cold. The most recent case as they were in a small insulated house which was heated by a light. The light does provide a significant increase in temperature inside the house. So at the moment I am at a bit of a loss as to why these seeminly healthy ducklings ar showing up deac without warning. Wondering if anyone here can shed any light on what it might be? Maybe the ducklings are a second or third clutch within 12 months for the mother and less robust. But still Id have thought there would be some signs all was not well, lethargy not eating, etc. every time, they have been energtic, alert, eating well and so on. The mother has been brooding them often, and is very protective of them and diligently watches them all constantly. My neighbours say she has been around here for years and raise many clutches so she is t a new mother who hasnt figured out how to raise them.