Flying Rats
Flying Rats are 200 collectible pigeons located all around Liberty City in GTA IV which Niko must find and shoot. The pigeons are generally found in out-of-the-way areas, but can be easily noticed by the distinctive cooing sound they make and the red glow they're highlighted with. Killing all 200 Flying Rats adds 2.5% to the Game Completed Percentage and also unlocks an Annihilator helicopter on a helipad near Star Junction in Algonquin.