To candle a canary egg, you’re looking at seeing through the shell but not actualy cracking it open. That’s important with canaries since their hatching time is just 2 weeks long. By holding the egg up to the light you know if there is something developing or not. Larger birds takes longer, so this isn’t as critical with them. However, it does get rid of non-viable eggs. This keeps the incubator clean and lets you know that your remaining egg are developing on track.
So how do you know when to expect what? You’re not just guessing… Refer to chart (above) for what you should be seeing daily. Early on, it’s going to look basically empty, with perhaps just the slightest hint of a yolk shadow if your light is good enough. By the third day, there will be thin red lines present, indicating it’s a fertile egg. Several days after that, those lines becomes thicker and form a web. Next, you’ll start to see movement. A tiny dark speck move and twitches around.
How to Candle Canary Eggs
The air space at the blunt end enlarges (you can actualy see this happen), which indicates moisture is being lost from the egg at an appropriate rate. Those are all signs of temperature and humidity. When environment remains consistently warm, an embryo develops nonstop without interruption, and when it’s not dry to the point where membrane hardens, than development can proceed unhindered. You can also see through candling if the air cell expand too rapidly or if it does not expand enough before hatching.
You’ll also want to turn your eggs daily for a few days at least so blood vessels distributes evenly throughout and the embryo isn’t stuck in a single location as it approaches the homestretch. Checking too early or leaving eggs out too long while they look is how most folks gets into trouble. You won’t see much detail worth noting on day 1 or even day 2. In fact, chilling eggs during inspection will slow development. This matter at this small size. Both issues are solved by working in a totally dark room and removing each egg for no more than half a minute. And to avoid wondering if you turned all your eggs, mark one end of the egg shell with a soft pencil.
By this time (day 10), the chick has grown enough to occupy most of the interior, pushing the air cell upward and making the egg mostly dark outside. If you have one in there with a definite ring of red around it rather than just veins, you’ll know the embryo began then died early; better to toss it now before it infects other good egg. Or if the egg appears totally transparent, feel free to dump it too, safe to assume no life’s ever forming in there.
It’s rewarding, but only if you’re patient. You should of not get your hopes up too much each time; just trust that the shell will slowly get darker and the air cell will gradually expand. When it does pip, all your labor with the light will have paid off: more hatching, less surprise. It goes from nothing but a little egg to something with wings. That’s what makes this worth the wait.