As with all birds, a sexual liaison must occur between male and female for fertilisation to be achieved. Unlike pigeons, chickens are polygamous creatures, so one male will happily mate with lots of hens, the ideal ratio being about 5 females to 1 male. There is little tact or ceremony on the part of the male. He selects the female (usually the closest one to himself) droops one wing to the ground, circles her then grabs her by the back of the head and climbs on her back. Balancing himself by flapping his wings, he lowers his tail and places his vent in direct contact with that of the hen, where the passage of sperm from his cloaca to her oviduct takes place. The entire sex act takes less than 15 seconds and it appears the most satisfying thing for the female is fluffing the feathers and shaking the body immediately afterwards.
It turns out this is true for humans also.
Damn girl, I haven't pulled tail in a long time. I'd settle for some chicken sex tonight.