How to determine if a bird egg is alive

So you’ve stumbled upon a bird’s nest and noticed a mysterious egg nestled among the twigs and leaves. Curiosity piques as you wonder: is the egg alive? Whether you stumbled upon this article out of pure curiosity or with the intention of rescuing the potential feathered friend, fret not! In this guide, I will show you simple yet effective ways to determine if a bird egg is alive, allowing you to truly understand the mystery that lies within that delicate shell.

Color and condition of the eggshell


Normal coloration

In general, bird eggs come in a wide variety of colors, ranging from pure white to shades of cream, beige, blue, green, or brown. The color of the eggshell can vary depending on the species of bird, with some eggs even featuring speckles or patterns. For most birds, the coloration of the eggshell is determined by pigments present in the bird’s diet during the egg formation process. So, if you come across an egg with a color that seems typical for the species, it is likely in good condition.

Abnormal coloration

While most eggs have a natural range of colors, there can be instances where the coloration seems unusual or different from the norm. Some common abnormal colorations include excessively pale or faded shells, extremely dark or splotchy coloration, or even eggs with a metallic sheen. These abnormal colorations can be an indicator of various conditions, such as poor diet, stress, or even diseases within the bird. If you encounter an egg with abnormal coloration, it may be worth consulting with a bird expert or ornithologist to understand the underlying cause.

Cracked or damaged shell

Inspecting the condition of the eggshell is crucial in determining whether an egg is alive or not. A cracked or damaged shell can significantly impact the chances of a successful hatch. If you come across an egg with visible cracks or fractures, it is important to handle it with extreme care. Cracks in the eggshell can allow bacteria or fungi to enter, potentially harming the developing embryo. Additionally, a damaged shell can compromise the structural integrity, making it difficult for the chick to break free during hatching. If you encounter a cracked or damaged egg, it is advisable to seek professional guidance from a knowledgeable bird expert.

Egg candling

What is egg candling

Egg candling is a technique used to observe the contents of an egg, particularly the embryo, by shining a light through the shell. This method allows us to determine if an egg is alive, monitor its development, and identify any potential issues. Egg candling is commonly practiced in bird breeding programs, research facilities, and with poultry farmers, as it provides valuable information about the viability of the embryo and the overall health of the egg.

Supplies required

To perform egg candling, you will need a few essential supplies. The primary requirement is a source of light, such as a bright flashlight, a candle, or specialized egg candling equipment. It is important to ensure that the light source produces sufficient illumination to penetrate the eggshell and reveal the internal structures. Additionally, you may need a dark or dimly lit room to enhance the visibility of the contents.

The process of egg candling

To candle an egg, you should first darken the room or find a dimly lit area where you can clearly see the light passing through the egg. Gently hold the egg in one hand and position the light source behind it. Slowly rotate the egg while observing the illuminated internal structures.

During the initial stages of development, you may notice delicate spiderweb-like veins extending from a central point. These veins, known as chorioallantoic membrane or CAM veins, are responsible for delivering essential nutrients and oxygen to the growing embryo. As the incubation period progresses, you may observe a dark or opaque mass within the egg. This mass corresponds to the developing embryo, and its size and shape can provide insights into the stage of development.

In some cases, you may even witness slight movements within the egg during candling. These movements can indicate that the embryo is alive and actively developing. Lastly, heat production is another sign of a living embryo. By placing the egg against your cheek or forehead, you might be able to detect a subtle warmth. However, be cautious not to exert too much pressure or accidentally drop the egg during this process.

Embryo development signs


When candling a fertile egg, one of the early signs of embryo development that you may observe is a network of tiny veins. These veins, known as chorioallantoic membrane or CAM veins, can become visible after a few days of incubation. They appear as delicate spiderweb-like structures, radiating from a central point towards the outer edges of the egg. The presence of these veins indicates that the embryo is developing and receiving the necessary nutrients and oxygen from the vascular system.

Dark or opaque mass

As the incubation period progresses, you may notice a dark or opaque mass within the egg during candling. This mass corresponds to the developing embryo and its surrounding structures. Its size and shape can provide valuable insights into the stage of development. As the embryo grows, this mass becomes more defined and may even show discernible features such as a head or limbs, depending on the species. The presence of a clear, well-formed mass suggests a healthy and developing embryo.


During the later stages of incubation, you might be lucky enough to witness some movement within the egg when candling. This movement can indicate that the embryo is alive and actively developing. The motions can range from subtle twitches to more pronounced shifts as the chick flexes and adjusts its position inside the egg. If you notice any movements during candling, it is an encouraging sign that the egg is alive and progressing towards hatching.

Heat production

Another sign of a living embryo that you can potentially detect during candling is heat production. The developing embryo generates heat as a byproduct of its metabolic processes. By gently pressing the egg against your cheek or forehead, you might be able to perceive a subtle warmth. When performing this test, exercise caution not to apply excessive pressure or mishandle the egg, as it can harm the embryo. Sensing heat production can provide added assurance that the egg is alive, but it should not be the sole determining factor.

Smell test

Fresh or neutral smell

One of the simplest and quickest methods to determine if an egg is alive or not is to perform a smell test. A freshly laid or fertile egg typically has a neutral or slightly sweet smell. If you notice no distinct odor or if the egg smells fresh, it is an indication that the internal contents have not begun to decompose. This suggests that the egg is likely alive and suitable for incubation.

Decaying odor

On the contrary, a decaying or foul odor emanating from the egg is a strong indicator that the embryo has perished. As an egg deteriorates, harmful bacteria begin to break down the internal contents, releasing unpleasant gases and producing a distinct smell of decay. If you encounter an egg with a foul odor during your assessment, it is best to discard it promptly to prevent any potential contamination or health risks to both humans and other eggs.

Float test

Performing the float test

The float test is a popular and straightforward method used to determine the vitality of an egg. To perform this test, you will need a container deep enough to submerge the egg completely in water. Fill the container with water, ensuring that it is at room temperature, and gently place the egg into the water. Observe the egg’s behavior in the water.

Interpreting the results: alive or not

Once you have placed the egg in the water, there are two possible outcomes:

  1. Floating: If the egg floats to the surface and remains buoyant, it may indicate that the air cell within the egg has expanded due to the gases produced during decomposition. This suggests the embryo inside the egg is no longer alive, and the egg is not suitable for incubation.

  2. Sinking: If the egg sinks to the bottom of the container, it suggests that the air cell is relatively small, and the egg is more likely to be alive. While the float test can provide some insight, it is not a foolproof method. As such, it is important to consider other signs of embryo development, such as movement or a fresh smell, to ensure accurate conclusions.

Egg weight

Normal weight range

The weight of a bird egg can vary depending on the species, but there is generally a range considered normal for each. For example, chicken eggs typically weigh between 55 and 60 grams. Understanding the normal weight range for the specific bird species whose eggs you are assessing can help you determine if an egg’s weight is within the expected parameters.

Unusually light or heavy eggs

When evaluating the weight of an egg, significant deviations from the expected range might indicate potential issues. If an egg feels unusually light, it could suggest that the egg has lost moisture or that the embryo has perished. Conversely, an egg that feels abnormally heavy might indicate excessive moisture content or the presence of a dead embryo. However, it is important to note that variations in environmental conditions or the stage of incubation can also contribute to slight fluctuations in egg weight. Therefore, it is always advisable to consider other indicators, such as candling or the presence of smells or movements, before making a final determination.

Eggshell temperature

Thermal imaging

Thermal imaging is a useful technique to assess the internal temperature of an egg. It involves using an infrared camera or a thermal imaging device to capture the heat patterns emitted by the eggshell. By visualizing the temperature distribution, you can gauge whether heat is being generated internally.

Using a body heat-sensitive material

If you don’t have access to specialized thermal imaging equipment, you can also use a body heat-sensitive material, such as liquid crystal thermometers, to estimate the eggshell’s temperature. These thermometers change color based on the temperature they come into contact with, allowing you to identify areas of varying heat emission on the eggshell. Observing warmer regions may indicate the presence of a living embryo, while cooler areas might suggest otherwise. Nevertheless, it is important to exercise caution and handle the egg carefully during these temperature assessments to avoid any potential harm to the developing embryo.

Eggshell movement

Observing slight vibrations

When an egg has a living embryo inside, you may be able to observe slight vibrations or movements of the eggshell. These subtle movements are caused by the developing chick’s muscle contractions and indicate the presence of an active and viable embryo. While you may not always notice these vibrations, particularly during the early stages of incubation, they become more prominent as the chick develops and gains strength. If you detect such movements, it is a positive sign that the egg is alive and progressing towards hatching.

Detecting small shifts

In addition to vibrations, you can also detect small shifts in the position of the eggshell during candling. These movements indicate that the chick is actively repositioning itself inside the egg. The ability to monitor these shifts can provide valuable insights into the chick’s growth and the development of its musculoskeletal system. If you observe these visible shifts, it further confirms the presence of a living embryo inside the egg.

Parental behavior and nest condition

Parental absence

Observing the behavior of the adult birds can also be a valuable indicator of whether an egg is alive or not. If both adults are consistently absent from the nest for extended periods, it may indicate that the eggs have been abandoned. Parental birds play a crucial role in incubating the eggs, regulating their temperature, and ensuring their safety. Therefore, the prolonged absence of parental birds is a concerning sign, suggesting that the eggs may no longer be viable.

Abandoned or damaged nest

The condition of the nest can also provide insight into the viability of the eggs. Abandoned nests, signs of predation, or significant damage to the nesting site may indicate that the eggs have been compromised or rendered unviable. Parental birds invest time and effort in constructing and maintaining their nests to provide a safe environment for their eggs and future offspring. Any disruption or lack of nest maintenance can affect the overall chances of successful hatching.

Incubation period

Determining expected hatching date

Each bird species has a specific incubation period, which is the duration it takes for the eggs to hatch. By knowing the typical incubation period for a particular species, you can estimate the expected hatching date. It is essential to consult reliable sources such as ornithology guides, bird experts, or online databases to obtain accurate information on the expected incubation period for the species of interest. Keep in mind that variations in environmental conditions, such as temperature and humidity, can slightly influence the incubation period, so it is best to use the expected range as a guideline.

Extended incubation period

If the incubation period surpasses the expected hatching date without any signs of activity or development, it can suggest that the egg is no longer alive. While there can be instances where the hatching process takes longer due to various factors, such as low temperatures or genetic abnormalities, an extended incubation period beyond the accepted range should raise concerns. Monitoring the egg closely during this period and consulting with experts can help determine the best course of action and understand the potential reasons for the delay.

In conclusion, determining whether a bird egg is alive involves multiple indicators and assessments. By considering factors such as color and condition of the eggshell, embryo development signs, smell tests, float tests, egg weight, eggshell temperature, eggshell movement, parental behavior and nest condition, and the incubation period, you can gain valuable insights into the vitality of the egg. Remember to exercise caution and seek guidance from experts or professionals when in doubt. Respect the natural processes involved in bird reproduction and always prioritize the welfare of the birds and their offspring.





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