There are two maps, with 100 pigeon locations on each. You will most likely come across pigeons that are marked on the other map, but it would be best to leave them alone until you are finished with the first if not using the two maps in conjunction.
The maps will guide you to the general location of the pigeon, but you'll have to refer to the text descriptions and screenshots to pinpoint them, as most are difficult to spot. The pigeons emit an orange glow, like that around weapons and armor, so the pigeons tucked away in dark places aren't impossible to make out. You'll also be able to hear the pigeon's call when you're really close.
The text descriptions are nigh useless without the map, so be sure to refer to the map to get a general idea of where the pigeon is hidden before looking to the text for clarification. The pigeons are not numbered in any coherent order, so go about getting them however you wish, though it might be convenient to follow the numbering in place. The larger circles signify that there are more than one pigeon at that location.
A sniper rifle with plenty of ammo, and in some instances a helicopter (you can take one of the Helitours Mavericks from the landing site in Fishmarket South, Algonquin).
Finish the story - Or at least have all of the islands unlocked before attempting this. It would be best to ignore the pigeons you stumble across while you're playing through the main storyline, as you will have a hard time trying to remember which ones you've snuffed out once you're ready to use a guide such as this one to find them all.
Use Waypoints - Approximate the location that is depicted on the map and place a waypoint there. This way you won't have to constantly pause the game to make sure you're headed in the right direction.
Sleep Mode - Put Niko's cell phone on sleep mode while pigeon hunting to avoid being constantly bombarded with calls from your acquaintances. Since you'll likely be at this pigeon hunting thing for awhile, your friends will start to hate you if you keep turning them down, and that's not a good thing. To enable sleep mode, open the Options menu and scroll down to “Turn Sleep Mode On.”
Double Check - If you happen to come across a pigeon yourself, it might benefit you to read the text description just the same to ensure that you killed the correct one. This way, you'll avoid confusion if you happen to mistakenly kill a pigeon that is marked on the other map.
Kill Count - You can check your progress via the “Score” screen in the Stats section of the pause menu. Your kills are recorded under the “Pigeons exterminated” stat.
