Why?

[Sylviaanne]

I apparently have a Cayuga Drake, 2 Pekin hens and a Fawn Indian Runner. I usually get 2 off white eggs and a blush or another shade of white egg per day. Right now my IR is broody but she was off the nest and I was checking the eggs. One looked bruised. I have had several eggs look like this and they are always bad when they get to looking bruised. I believe it is the same duck laying these eggs but I don't know which. I candled this egg and it looked like the duckling had started to develop but stopped for some reason. The IR wasn't the only one laying eggs in the nest when she decided to become broody.

What I am wondering is: why these eggs turn dark and look bruised? My chicken eggs don't turn colors when they go bad and the blush duck eggs don't turn colors. Any idea what causes this?

 

[subhanalah]

When I was hatching duck eggs, the air sack started turning blue. I didn't know what was going on, but made it really easy to assure proper placement of the air cell at hatching! I didn't even have to candle them.

 

[Sylviaanne]

When I was hatching duck eggs, the air sack started turning blue. I didn't know what was going on, but made it really easy to assure proper placement of the air cell at hatching! I didn't even have to candle them.

Were they fertile and did they hatch? If so, sounds like you were lucky. What breed?

 

[subhanalah]

Yes and yes. Welsh harlequins. The only other time I've ever incubated duck eggs, they also developed discoloration during incubation.
*shrugs*