Blood ring in most of the eggs

[WVduckchick]

Blood rings just happen when the embryo starts, then stops developing. Some say heat spikes, some say too high humidity, shipped eggs are famous for early quitters.

I had several blood rings in some call duck eggs I set recently that had none of the things listed above, but they were from young layers, so I think that was the cause in my case.

 

[Tlmcq]

These were not shipped and think I have another one that looks like may be forming blood ring now...last one was chicken at around 12 days this is a duck about 15 days. I'm leaving it in for few more days just in case since lil duck in there was moving few days ago and there was a bit of progressing development since last candling and slight decrease in air sac. Temp has been stable and good according to 2 thermometers one digital one regular and humidity was slightly low this morning but pretty stable otherwise. I added water to sponge and came back to normal this afternoon. Just trying to make sure I'm not doing something to cause this.