Birds - Reproduction

Differences between male and female birds Different reproductive organs. Many males have ornamentation. More impressive appreance to attract the female bird. Differences in behaviour – the male birds have mating calls/songs to attrack the female bird.

Reproduction The Reproductive Anatomy of Birds Most birds do not have the same reproductive body parts as mammals. Both the male and female birds have a cloaca – an opening that serves as the bodys exit for the digestive, urinary and reproductive system.– During the breeding season (spring) the cloaca swells and protrudes slighty outside the body.When the birds are ready to breed the reproductive organs swell (the testes and the ovaries) and produce the sprem and ova. Male birds store sperm in their cloaca until an opportunity arises. Females will recieve that sperm into their cloaca before it travels to fertilize their ova.

Development of an Egg The egg goes through 3 important phases: – The development of the egg – The incubation of the egg – The hatching of the baby bird

The Formation of an egg The Yolk: The egg starts as an egg yolk inside a hen. A yolk is produced by the hen's ovary in a process called ovulation. Fertilization: The yolk is released into the oviduct (a long, spiraling tube in the hen's reproductive system), where it can be fertilized internally (inside the hen) by a sperm. The Egg White (albumin): The yolk continues down the oviduct (whether or not it is fertilized) and is covered with a membrane (called the vitelline membrane), structural fibers, and layers of albumin (the egg white). This part of the oviduct is called the magnus. The Chalazae: As the egg goes down through the oviduct, it is continually rotating within the spiraling tube. This movement twists the structural fibers (called the chalazae), which form rope-like strands that anchor the yolk in the thick egg white. There are two chalazae anchoring each yolk, on opposite ends of the egg. The Eggshell: The eggshell is deposited around the egg in the lower part of the oviduct of the hen, just before it is laid. The shell is made of calcite, a crystalline form of calcium carbonate. This entire trip through the oviduct takes about one day.

Formation of an egg

Formation of the egg

Incubation Period Usually the female bird will sit on the eggs in her nest to keep the eggs warm. The eggs require a warm temperature to develop. The downy feathers under the belly are used.