Animals have sex in all sorts of weird and wonderful ways. Birds have sex via an internal chamber called a cloaca that is present on both male and female animals.

Male Japanese quails produce a strange seminal foam that appears to enhance the chances of successfully fertilizing an egg.

Singing is an important part of the breeding cycle, which begins when migratory male birds reach their nesting grounds. They usually arrive before the female birds, giving each male time to ...

The bird appeared to be a bilateral gynandromorph: female on one side and male on the other. “It was just incredible,” Dr. Spencer said. “We were lucky to see it.” ...