If you are planning to breed pigeons, it's vitally important to know the sex of your birds. Unfortunately, determining the sex of pigeons can be challenging, and even expert pigeon keepers can be fooled. By observing physical and behavioural characteristics, though, you can make an educated guess about the sex of your pigeons.
Observe the size of full-grown pigeons. Male pigeons are generally larger than female pigeons.
Examine the pigeon's cloaca. To do this, run your fingers down the pigeons chest toward the tail. Just before you reach the tail bone, you will notice two small bones that come together in a v-shape. If the bones are wide enough apart to fit one finger, the pigeon is likely a female. Female pigeons have a larger separation in these bones to allow the egg to pass through. If the bones are very close together, your pigeon is likely a male.
Observe your pigeon's behaviour. Males tend to fan out their tails more frequently than females do. Males may also peck the heads of females. If you see a bird frequently pecking another bird who never pecks back, the pecker is likely a male.
Listen to your bird's calls. Males tend to be more vocal than females, and their calls also last longer and are louder than females'. The loudest birds in your flock are probably males.
Not all pigeons will follow the "gender rules" for behaviour, so it's important to examine your bird's cloaca. If you're still not sure, consult an avian veterinarian.