How Do Roosters Identify Hens?

[McChooky]

They speak their own language & communicate very well with one another (thru sounds and body language) They can recognize the difference between the mature hens and immature pullets by their appearance, body language and how they interact in the flock .The hens also submit and squat.

 

[Shewstock]

Birds can't sniff, they really don't have a sense if smell.

Pk, so why does he stick his beak near their vent? The ones not "ready to mate" he doesn't top. The ones that ARE ready he tops.