Because they are high level predators, peregrine falcons play an important role in regulating populations of their prey, particularly pigeons and doves (Columbidae), ptarmigan (Lagopus), and ducks (Anatidae)

Peregrine falcons are susceptible to many parasites and diseases. External parasites include chewing lice (Phthiraptera), fleas (Ceratophyllus_garei), and flies (Icosta_nigra and Ornithoctona_erythrocephala). Internal parasites include strigeid trematodes (Strigeidae), nematodes (Serratospiculum_amaculata), and tapeworms.

Commensal/Parasitic Species:

• Ornithoctona_erythrocephala
• Icosta_nigra
• Ceratophyllus_garei
• Nosopon_lucidum
• Laemobothrion_tinnunculus
• Degeeriella_rufa
• Colpocephalum_zerafae
• Plasmodium_relictum
• Serratospiculum_amaculata
• Strigeidae