How does a male bird physically fertilize the hen or the egg?

The rooster picks a hen to mate with and does a dance around her, the hen will indicate receptiveness by lowering herself closer to the ground and the male will grasp her neck feathers and stand on her back. The male chicken does not have a penis and therefore there is no penetration of the female reproductive tract at the time of mating. The female inverts her cloaca which is the common junction of the reproductive and digestive systems. Her cloaca comes in contact with the male's inverted cloaca and receives the sperm. The cloaca is then drawn back into the hen's body and the sperm are captured. Sperm then begins the journey up the length of the reproductive system. The sperm live inside the female reproductive system and each time an ovulation occurs (every 24-26 hours in good egg producers) the egg can become fertile. This process continues and matings at 7 - 10 day intervals are necessary to maintain fertility.