So, I didn't notice the Fayoumi was laying in the broody's nest box at first and I'm not sure the original eggs she was sitting on were fertilized, but I pulled everything out and candled when I noticed a couple weeks ago. She is currently sitting on 4 eggs that look like they're closing in on...
I haven't used a slow cooker for rendering, but do you think that perhaps the lid allowed moisture to gather and drip back down? It's possible you have two different fat densities, but you'll have to open one up to be sure what you're dealing with.
Sudden deaths are a good time to contact you local agricultural extension to have the corpses tested for things like bird flu. In North Carolina they have had some H5N1 cases popping up in ducks. Waterfowl carry and spread it without getting sick. Sudden deaths can be caused by multiple things...
Stop adding vinegar, it messes with calcium uptake. Raw apple cider vinegar can be offered as a probiotic occasionally in a separate waterer, but should never be added continuously to the only available water source.
Yeah biosecurity went out the door a while back. I'm keeping a close eye on them, I think we're in the clear so far, first contact was in November. As soon as I gain the trust of the new birds and get a coop together I'm going to coop them up for a bit and see if I can't get them to stop...
Not the best picture, but I think you see what happened...
This morning 3 more buttercups showed up, they look a little rough, but it could just be that they're moulting. No sign of the other Fayoumi yet. So I guess the day care is officially open. This whole situation has been crazy, 5 birds in...
Sounds like it may have a tiny yolk. Fairy eggs can have some till, it's usually just not a fully developed one. I don't think it's a viable egg. If you're super curious and it doesn't smell you can give it a couple more days, but honestly I would be shocked to see anything happen.
Can you see a yolk in person? Not seeing one in photos yet. No yolk would support fairy egg. I didn't think fairy eggs were super rare, no yolk and double yolks have been very common in both my chickens and quail when they first start laying.
As others have said, I watch the birds not the temps and follow their cues. I'm in a hot climate so I usually have chicks off the heat towards the middle of week 3. I brood indoors for the first couple days to be sure everyone is eating and drinking, and there's no issues with legs and feet...
I am less familiar with duck eggs, but believe they actually benefit from short cooling periods.
I have had both quail and chickens survive 8 hour power outages with no assistance from me besides wrapping the incubator with a blanket.
Hopefully someone with more duck specific knowledge will...