Which of the following is the largest bird listed?

The Jerkin, also known as the Gyrkin or Gyrfalcon, is recognized as the largest bird among the options listed. Gyrfalcons are known for their impressive size and can weigh between 3 to 4.6 kilograms (6.6 to 10.1 pounds), with wingspans reaching up to 1.5 meters (approximately 4.9 feet). Their size and robust build make them distinct within the falcon family, allowing them to hunt larger prey compared to other falcons.

The other birds mentioned—Jack Merlin, Peregrine Falcon, and Peregrine tiercel—while also being remarkable raptors, do not reach the same size as the Gyrfalcon. The Jack Merlin and Peregrine Falcons are generally smaller, with the Peregrine typically ranging from 0.7 to 1.5 kilograms (1.5 to 3.3 pounds) and having a wingspan of about 1 meter (3.3 feet). The term "tiercel" refers specifically to male falcons of the species, which tend to be lighter and smaller than their female counterparts, further emphasizing the larger stature of the Gyrfalcon in comparison.