Determining whether a bird egg is fertilized or not can be important for bird owners and breeders. A fertilized egg means the egg has been bred and will hatch into a healthy baby bird. An unfertilized egg will never hatch. There are a few ways to tell if a bird egg is fertilized or not.
Candling the Egg
One of the most common ways to check for fertilization in an egg is a process called “candling.” This involves shining a bright light through the egg shell to see inside of it. Here’s how the candling process works:
- Use a bright flashlight or egg candler designed for this purpose. An egg candler has a bright light source on one end.
- Go into a dark room and hold the uncracked egg up to the candler light source. Shine the light through the egg.
- Look through the egg. If it’s unfertilized, you will only see the shadow of the yolk and uniform yellow/orange color. If it’s fertilized, you will see a small dark spot (the developing embryo) and spiderweb-like veins radiating from it.
Candling an egg allows you to see inside of it without cracking it open. It’s a safe, non-invasive method. Here are some key things to look for when candling an egg:
Fertilized Egg | Unfertilized Egg |
---|---|
– Dark spot or embryo | – No dark spot |
– Spiderweb veins | – Even color and shadow |
Candling is best done after at least a few days of incubation. Very freshly laid eggs are harder to analyze. The air pocket inside enlarges with incubation, making it easier to distinguish features.
Breaking Open the Egg
Breaking open the egg and looking inside is another definitive way to determine fertilization. This destroys the egg, so only do it if the egg is intended for eating, not hatching. Here’s what to look for when opening an egg:
- Fertilized Egg – You will see a small, distinct embryo attached to the yolk, reddish veins, enlarged blood vessels. You may even see a heartbeat if the embryo is developed enough.
- Unfertilized Egg – The yolk and white will be uniform with no distinct embryo spot or veins.
As a general guideline, fertilized eggs will show identifiable embryos after roughly 1 week of incubation. Opening the egg is the most surefire way to know, but also destroys the egg. It’s best used for eating eggs, not breeding.
Floating or Sinking in Water
Testing whether an egg sinks or floats in water can potentially indicate fertilization. Here’s how to do it:
- Fill a bowl with room temperature water.
- Gently place the uncracked egg into the bowl of water.
- A fertilized egg will likely sink to the bottom.
- An unfertilized egg will likely float or stand upright at the bottom.
Why does this work? As the embryo develops, the interior of the egg becomes denser. This makes a fertilized egg more likely to sink. But note this isn’t a completely foolproof method. Factors like egg shape and air pocket size can also influence floating.
Stop Candling After Seeing Veins
When candling an egg, you can stop as soon as you see the spiderweb-like veins or distinct dark spot. At this point you can be confident the egg is fertilized. Continuing to candle after veins appear will only risk damaging the developing embryo or disrupting incubation. Minimizing light exposure preserves the health of the embryo.
Look at Egg Shape
The shape of an egg can provide hints about its fertilization status:
- Rounder shape – Tend to be fertilized eggs
- More elongated shape – Tend to be unfertilized
However, egg shape is an inexact science. The bird’s diet, health, and other factors also affect it. Use in conjunction with other methods like candling for best accuracy.
Listen for Sounds
If you listen closely, you may be able to hear faint sounds coming from a fertilized egg. Press your ear gently against the egg and listen. If fertilized, you may hear a faint pulsing sound from the embryo’s heartbeat. Chirping or tapping sounds can also sometimes be heard as the embryo develops.
However, this method is quite difficult and unreliable for the average person. It takes an experienced breeder with a trained ear. Use other visual methods in combination with listening for the most reliable results.
Notice Lack of Egg Rotation
Bird parents instinctively rotate and move their fertilized eggs. This helps the embryo stay centered in the shell. If you notice an egg hasn’t moved at all from its position, it may be unfertilized. The parents do not bother rotating eggs that won’t hatch.
However, some birds may stop rotating an egg if they sense the embryo has died. So lack of movement alone isn’t definite proof. Use in combination with other signs like candling for accuracy.
Weigh the Egg
As the embryo inside grows, a fertilized egg will gradually gain weight. Weighing an egg periodically on a precision gram scale can determine if it’s gaining weight:
- Mark the egg clearly with pencil so you know it’s the same one.
- Weigh the egg, record the exact gram weight, and date it.
- Weigh again in 4-7 days. Fertilized eggs gain 10-15% in weight.
If the egg has not increased in weight at all, it is likely unfertilized. But if weight steadily increases over multiple checks, it indicates fertilization. This method takes more time and diligence than others.
Other Potential Signs
Some other subtle signs that may indicate a fertilized egg include:
- – The parents are observed breeding
- – The mother lays more than just 1 egg
- – The parents are protecting and sitting on the egg
However, these are quite unreliable methods on their own. Use other more definitive techniques like candling to be sure of fertilization status.
Conclusion
Determining if bird eggs are fertilized requires close observation, but several effective methods are available. Candling is the most common and reliable technique. Looking for embryos upon opening, floating/sinking tests, weighing, and other signs can also help provide the answer. Use a combination of visual, audible, and intuitive techniques for the most accurate results.