Checking if a bird egg is still alive is an important part of caring for bird eggs. When incubating bird eggs, it is normal for some eggs to stop developing or die at various stages. However, it can be difficult to determine if an egg is still viable or not. This article will go over several methods and techniques used to check for signs of life in bird eggs.
Candling the Egg
One of the most common ways to check the status of a bird egg is a process called “candling”. This involves using a bright light source behind the egg to illuminate the inside and observe the embryo and blood vessels. To candle an egg, you will need a bright focused light such as a flashlight, LED candle, or candling light designed for egg inspection.
Candling works because the egg shell is semi-translucent and allows light to pass through it when illuminated from behind. The air cell at the large end of the egg shows up clearly as does the network of blood vessels radiating from the embryo if development is underway. As the embryo develops, its shadow will be visible as will the amniotic fluid surrounding it.
To candle the egg, hold the large end up to the light source in a dark room. Examine the inside of the egg looking for signs of development. A live embryo will appear as a dark spot or shadow surrounded by a spider web of blood vessels. The air cell will also appear as a clear bubble at the rounder end. If the contents appear muddy or unclear, this often signals a non-viable egg.
What to Look for When Candling
Here are some tips on what to look for when candling a bird egg:
- Live embryo – Look for a dark shadow with distinguishable shape and visible blood vessels radiating outward.
- Enlarging air cell – As the embryo develops, the air cell at the round end enlarges. This is a positive sign.
- Blood vessels – Look for a network of blood vessels branching from the embryo to the edges. Clear, small vessels indicate a live egg.
- No blood vessels or embryo – This likely means the embryo died at an early stage. The egg will appear muddy or unclear.
- Enlarged blood vessels – As an embryo dies, the blood vessels enlarge and darken. This is an indicator the egg is no longer viable.
Candling offers a minimally invasive way to inspect eggs for signs of life. It should be done carefully and briefly to avoid damaging the developing embryo. Candling can be done periodically during incubation to monitor progress.
Visual Inspection
Another method is to visually inspect the egg carefully for any external signs that might indicate the status of the embryo inside. Here are some things to look for:
- Egg shape and shell condition – As the chick develops, the egg shape may change from perfectly oval to more rounded on one side as the air cell enlarges. Cracks, dents, or a misshapen egg could signal problems.
- Discoloration – A pink, yellow, or brown tint can indicate bacterial contamination or a non-viable embryo. Healthy eggs appear white or cream colored.
- Shaking the egg – Gently shaking the egg and listening for movement can tell you if the chick is still active inside. Be very careful not to shake vigorously or damage the embryo.
- Holding to light – Carefully hold the egg up to a bright light. A dark spot or shadow indicates the embryo, while a clear egg means it stopped developing early.
Visual inspection is non-invasive and can provide hints about the egg’s status when done carefully and diligently. Candling provides a much clearer picture, but checking the egg’s physical appearance can supplement the information gathered by candling.
Floating or Dunking
A more dated method is to lightly dunk eggs or float them in a bowl of water to determine if they are still viable. This technique has largely been replaced by candling as it is not as accurate and risks introducing contamination.
The concept behind water dunking or floating is based on the idea that as an egg deteriorates, the contents begin to shrink and the air cell enlarges. This increases buoyancy. So a viable egg will typically sink, while an egg that has gone bad will float.
However, there are many variables that make results hard to determine with certainty. Temperature of the water, thickness of the shell, age of the embryo and more can influence whether the egg sinks or floats. It is not a highly reliable indicator of viability.
Additionally, submerging eggs in water can introduce bacteria or drown a live embryo if water seeps through the shell. For these reasons, floating/dunking eggs is not recommended.
Opening the Egg
As a last resort, you may need to open the egg to get a definitive answer on whether the embryo is still alive. Before doing this, candle the egg and use visual inspection to make your best guess. Only open the egg if necessary as you will no longer be able to incubate the egg after that.
To open an egg:
- Use a small drill bit or thumbtack to carefully puncture a tiny hole in the top of the air cell end.
- Enlarge the hole by drilling slowly to about 1/4 inch diameter.
- With clean hands, gently crack the egg along the equator and pry it open. Be careful not to tear the inner membranes.
- Inspect the inside of the egg for signs of life. A live embryo will immediately move.
Opening the egg is a last resort but may be necessary if candling is unclear. Never open eggs without first taking precautions to ensure your workspace is sterile to avoid contaminating viable eggs.
Timing and Stage of Development
The expected developmental stage of the embryo based on the number of days into incubation can provide clues about whether it is still progressing normally. Here is a general timeline:
- Days 1-3 – No visible development
- Day 4 – First sign of embryo appearance
- Day 5 – Embryo and blood vessels visible
- Day 8 – Embryo surrounded by amniotic fluid, tail starts forming
- Day 10 – Wings visible, legs developing, arteries and veins present
- Day 14 – Scales and claws begin appearing, embryo starts moving into hatching position
- Days 15-21 – Yolk sac starts getting absorbed into the body in preparation for hatching
If you candle the egg and the embryo appears underdeveloped or abnormal for the incubation day, it may signal that it is non-viable. Comparing progress to a normal timeline can help reveal if development has ceased or slowed.
Listening
Carefully listening to a bird egg during incubation can sometimes indicate if there is movement inside. After day 14, a live chick will periodically move, scratch, or peck at the interior of the egg. Tapping the egg gently may stimulate movement.
To listen, place the large end of the egg against your ear. In a quiet environment, you may hear the faint sounds of a chick moving. Be cautious not to disturb the egg too much. If in doubt, compare against other eggs from the clutch that are known to be developing normally.
Listening for sounds does not confirm viability 100% but it can supplement candling inspections and visual checks to provide more clues about the embryo’s status.
Egg Weight
A developing embryo and chick will increase the overall weight of an egg as incubation progresses. Monitoring egg weight and looking for the expected gains can indicate a healthy growing chick.
To track egg weight:
- Weigh the eggs on an accurate digital scale at the start of incubation. Mark each egg with an ID.
- Weigh every 3-4 days and log the weight of each marked egg.
- Healthy eggs will gradually increase in weight due to moisture loss and the growing chick.
- Eggs that stop gaining or reduce in weight may have non-viable embryos.
Normal weight gain for most bird eggs during incubation is around 12-15% of the starting weight. Significant deviations could be a red flag.
Egg Respiration
Like all living organisms, bird embryos respire and produce carbon dioxide gas as a byproduct. This gas is released through pores in the egg shell. The rate of respiration can indicate if there is active life inside an egg.
Specialized devices called egg respiration monitors exist to carefully measure the levels of CO2 gas emitted by an egg during incubation. This can detect if the embryo has died or is in distress if respiration drops off or ceases.
For home incubation without monitors, you can candle the egg and seal it in an airtight plastic bag for a few hours. Then open the bag and smell – the presence of CO2 gives off a distinguishable odor. However this method is not as precise as using instrumentation.
Conclusion
Determining if bird eggs are still viable during incubation requires careful observation, candling, and tracking developmental cues. Candling using a bright focused light remains the most reliable method. It allows visual inspection of the embryo, fluids, and blood vessels to assess the life status.
Other techniques like floating, opening the egg, listening for sounds, weighing, and monitoring respiration can provide supplemental data. However candling should be the primary method. Perform candling gently after the first week of development and then every few days to monitor the growth progress. Seek for visible signs of a live embryo and network of blood vessels radiating outward.
With some basic equipment and diligent observation, bird owners and breeders can candle and monitor eggs for live embryos, allowing them to continue incubating only those with active development. This helps maximize hatch rates and efficiency in the incubation process. Proper candling and inspection skills are crucial for anyone incubating bird eggs to successfully hatch healthy chicks.
Frequently Asked Questions
How early can you candle a bird egg?
Candling can be done as early as day 5-7 of incubation. The embryo and blood vessels will start becoming visible around this time. However, candling too early during the first week is not as useful since the embryo is still very small.
Can you candle an egg too frequently?
It’s best not to candle eggs too often as excessive light exposure and handling can potentially impact the developing embryo. Limit candling to every 5-7 days. Daily candling is not recommended unless monitoring a known fertility issue.
Does candling harm the embryo?
Candling itself does not harm the embryo when done correctly for brief periods. However, excessive heat from the light source and prolonged, intense exposure could potentially impact development. Keep sessions brief, with minimal direct heat.
Can you candle eggs throughout incubation?
Yes, eggs can be candled at multiple points during incubation to monitor progress. However, avoid candling more than 1-2 times per week. Frequent disturbance and light exposure may affect normal development.
What does a dead embryo look like when candling?
A dead embryo may have enlarged, darkened blood vessels or appear as a indistinct shape without defined blood vessels. The contents may also appear muddy or unclear. Comparisons to live eggs makes it easier to identify non-viable embryos.
Can you save an egg with a dead embryo?
Unfortunately, once an embryo has died there is no way to revive it and save the egg. The only option is to remove and dispose of non-viable eggs from the incubator to avoid contamination.
Why do some eggs contain blood after candling?
If blood is visible after candling, it indicates that the embryo has ruptured or a blood vessel broke. This causes internal bleeding and means the egg cannot be saved or hatch. The egg should be disposed of.
How accurate is candling at determining if an egg is alive?
Candling by an experienced person is >95% accurate when done carefully under optimal conditions. It remains the most reliable method for assessing egg viability non-invasively. Perfect candling technique takes practice.
Can you save a cracked egg by sealing it with glue or tape?
It’s not recommended to attempt sealing a cracked egg as contaminants likely entered already. Even if you manage to seal it, the embryo likely sustained damage and its survival odds are very low. Discard cracked eggs.
Method | How it Works | Pros | Cons |
---|---|---|---|
Candling | Light illuminates egg interior to observe embryo and vessels | Non-invasive, clearly shows development | Requires some equipment, risks overheating |
Floating | See if egg floats in water to determine air cell size | Simple, no equipment needed | Not very accurate, risks introducing contamination |
Visual Inspection | Look for external signs like shape, color, etc. | Non-invasive, easy | Does not directly view embryo |
Opening Egg | Carefully open egg and inspect contents | Directly view embryo | Highly invasive, ends incubation |