For those of you unfamiliar with the term, "candling" is a method which bird breeders use to verify that eggs incubated for hatching are fertile. To candle an egg, a very bright light is held behind it to illuminate the shape of the embryo inside the shell. Fertility is determined based on the color, shape, and opacity of the contents. When no veining is present and the egg is very bright inside, we call this a "clear" egg, meaning it's unfertilized or otherwise not viable. It all usually starts with a dark spot, which grows veins, then the little baby inside begins to take shape and you can often see it moving when you shine your light on it.
Here are pictures of the eggs. These are not my best work, I haven't gotten the hang of ultra low light photography. At least they're not blurry, which requires a lot of steadiness and holding of breath for such a dark room.
The right temperature and humidity conditions must be reached before all the eggs in a clutch sort of "click on" and begin growing. This ensures that when the hen finally lays her last egg for a clutch that they all hatch within 24 hours of each other. An egg laid 6 days prior to her setting the nest begins growing at exactly the same time as the one she just laid. Right up until those perfect conditions are met, a fertile egg looks exactly like an infertile egg. Many people believe that a blood spot on the yolk is an indication, that only means that a bit of blood was trapped inside the egg when it was being formed... hens with no male to fertilize eggs lay those just as often as the ladies who have a man around.
I'm crossing my fingers on those two questionable American Blues. I've never hatched goose eggs before so I'm going off of past experience with chicken, duck and Muscovy eggs.
Speaking of which, that Muscovy girl that looked and sounded like she was considering setting a nest is a confirmed broody. She's been keeping a couple of wooden eggs warmed up and has created a beautiful nest for them, lined with downy feathers pulled from her own chest. Tonight I took these goose eggs out of the incubator and put them under her warm bottom. If they're gonna hatch at all, they'll do it under her expert care. Then she can raise those babies instead of me. I love babies but everyone will benefit from this pretty little Muscovy doing what she does best.