Gyrfalcon vs. Peregrine Falcon

unfortunately size barely means anything the air. peregrine falcons are known to knock out much larger birds such as pelicans, sea birds, and even other birds of prey, although these are normally results of high speed 200mph+ dives.
the two combatants are very similar. both have aerodynamic builds, a low wing loading, a high pointed center of gravity and v shape wings all in order to reduce drag and enable fast flight. assuming that both combatants are aware of each other, element of surprise and high speed dives are effectively neutralize. the gyrfalcon possess a size advantage and a compatible speed in both level and high speed flight, but a peregrine 's lighter build allows faster climb rates and increases maneuverability.
I'm calling this a 50/50 match