Birds produce eggs through a process that begins in the female bird’s ovary. When an ovum is released into the oviduct and fertilized, it starts as a protein-packed yolk. The gelatinous egg white, known as albumin, is added next. Subsequently, the mass plumps up with water and is encased in soft, stretchy membrane layers. This entire process takes place within the female bird’s reproductive system, specifically the oviduct.
Female birds can lay eggs, regardless of the fact that they have a mating partner. Without any interaction with male birds, female birds ovulate follicles from ovaries. During ovulation, the ovulated follicles come out of their body inside a shell.
Let’s get to the details of how birds produce eggs.
Do Birds Lay Eggs Throughout the Year?
The reproductive activity of a female bird acts in response to certain environmental factors, such as – length of the day, warmer temperature, spring season, etc. This triggers hormonal changes in the female bird and it prepares itself for laying eggs. However, pet birds do not get exposed to these environmental changes and so they are seen to ovulate and lay eggs quite often or maybe all year round.
Process of Egg Development in Birds
Birds when young grow with two ovaries, but as they get matured the right one gets regressed and the left one develops. After the egg or ovum ruptures from the developing follicle, it passes into the funnel end of the oviduct. Around this egg, a yellow coating develops, which acts as the food source in case the egg gets fertilized. The ovum which is present within the yolk gets an outer coating known as albumen or gelatinous egg white. Now, around this develops membranes within the egg and finally an outer shell.
The shell around the egg is made of calcium and other minerals, and it gets added when the egg is in the uterus. Next, the egg enters the cloaca and passes out of the body of the bird through the vent opening. This vent opening is the common chamber for the reproductive tract, urogenital tract, and gastrointestinal tract.
What if the Egg Gets Fertilised?
Before laying the egg, the egg gets fertilized, so it cannot be fertilized after it is laid. Fertilization takes place in the oviduct and right before it gets coated with yolk and egg white. The male sperm stays in the oviduct for several days and if it is unable to fertilize the egg, then it dies off.
Otherwise, when the ovum reaches the oviduct, the sperm penetrates and fertilizes the egg, and then the subsequent changes, as mentioned above, take place. Finally, the egg is passed out of the body from the vent.
Can You Make a Difference Between Fertilised and Unfertilized Eggs?
If you look at a fertilized egg, it looks similar to an unfertilized one externally. However, you can only make a difference – when the female bird sits on the egg to incubate it, if the egg is fertilized only then after a few days a baby bird hatch out. However, the hatching time period differs based on the species of bird you are dealing with.
Do Birds Lay Eggs Without a Mate?
Yes, there are some birds that can lay eggs without mating with a male bird and this process is called parthenogenesis. In this process, the embryo develops from an unfertilized egg and this is quite common among cuckoos.
Why Birds Sit On Their Eggs?
After laying the egg, the female bird sits on the egg and this process is called incubation where the eggs are kept warm so that the babies that are developing inside the eggs grow correctly without any damage.
How Many Times a Bird Lays an Egg in a Year?
A bird lays an egg once a year but some birds such as the American Robin can lay eggs 4 to 5 times within a single breeding season.
Which Birds Lays One Egg?
Birds that lay only one egg per clutch are – Albatrosses, Tropicbirds, Shearwaters, and Frigatebirds.
