How do racing pigeons choose a mate?

The strong survive tells all to your question, the Pigeon you see Strutting, head bobbing, charging type of behavior is the male, he is trying to woo a hen into submission, I am a Pigeon/Wildlife rescue & rehab person, I have many pigeons here, I have nesting boxes and watching the males try to lure a female into a nesting box is fun to watch, Males will also compete for a hen, some fights can become vicious.
The Pigeons do mate for life, however the (for life) issue can be looked at differently, If something was to happen to a Pigeons mate the survivor will except another mate in due time.
One is a lonely number.
They will only have 2 babies at a time, depending on the weather they will have up to 3 clutches per year.