Ostriches, the largest birds on Earth, produce the largest eggs of any living bird, weighing approximately 2.5 to 3 pounds (1,135 to 1,362 grams) and measuring about 6 inches (15 cm) in diameter. These eggs, with their thick, glossy cream-colored shells, hold the potential for new life.
The Ostrich Egg Incubation Period
Ostrich eggs typically take between 36 and 45 days to hatch. This incubation period is relatively short for an egg of its size. Incubation involves maintaining consistent conditions, primarily temperature and humidity, for the embryo to develop properly.
While natural incubation involves both male and female ostriches taking turns on the nest, commercial ostrich farming largely relies on artificial incubation. In natural settings, the drab-colored female incubates during the day, while the black male takes over at night. Artificial incubation aims to replicate these precise conditions to maximize hatching success.
Key Factors Affecting Hatching Success
Maintaining precise environmental controls is essential for successful ostrich egg hatching, whether in a natural nest or an artificial incubator. Optimal temperature for incubation is around 97.6°F (36.4°C to 36.5°C). Overheating can accelerate embryo development but may lower hatchability and cause abnormalities, while excessively low temperatures can kill the embryos. Humidity is equally important, maintained between 25% and 35% relative humidity, allowing for 15% weight loss from the egg due to water evaporation by external pipping.
Regular turning of the eggs prevents the embryo from sticking to the shell membranes and ensures uniform temperature distribution. Eggs should be turned at least twice daily until about the 39th day of incubation. Proper ventilation is also necessary for gas exchange, removing carbon dioxide and supplying fresh oxygen.
The Hatching Process
The hatching process for an ostrich chick is physically demanding. It begins with the internal pip, where the chick breaks through the inner membrane into the air cell. This provides the chick with access to air, allowing it to begin lung respiration.
Following a period of rest, the chick performs the external pip, using a temporary, sharp projection on its beak called an “egg tooth” to create the first small hole in the outer shell. After the external pip, the chick slowly rotates inside the egg, using its egg tooth and strong neck muscles to “zip” or cut a circular line around the shell. This strenuous process can take several hours, allowing the chick to eventually push off the cap of the shell and emerge. Human intervention is discouraged unless absolutely necessary, as premature assistance can harm the chick.