page_title: Peregrine falcon
section_title: Ecology and behaviour
hierarchical_section_title: Peregrine falcon / Ecology and behaviour
caption_attribution_description: English: Closeup of peregrine falcon showing nostril tubercle. Photo by Greg Hume
context_page_description: The peregrine falcon, also known as the peregrine, and historically as the duck hawk in North America, is a widespread bird of prey in the family Falconidae. A large, crow-sized falcon, it has a blue-grey back, barred white underparts, and a black head. The peregrine is renowned for its speed, reaching over 320 km/h during its characteristic hunting stoop, making it the fastest bird in the world, as well as the fastest member of the animal kingdom. According to a National Geographic TV program, the highest measured speed of a peregrine falcon is 389 km/h. As is typical for bird-eating raptors, peregrine falcons are sexually dimorphic, with females being considerably larger than males. According to one study, it has the fastest visual processing speed of any animal tested so far, and can register discrete changes up to 129 Hz or cycles per second. Analogically, film is a series of still images projected onto a screen. Those still images need to be changing at roughly 24 frames per second before humans see them as fluid and no longer as individual, discrete pictures.
context_section_description: The peregrine falcon lives mostly along mountain ranges, river valleys, coastlines, and increasingly in cities. In mild-winter regions, it is usually a permanent resident, and some individuals, especially adult males, will remain on the breeding territory. Only populations that breed in Arctic climates typically migrate great distances during the northern winter.
  The peregrine falcon reaches faster speeds than any other animal on the planet when performing the stoop, which involves soaring to a great height and then diving steeply at speeds of over 320 km/h (200 mph), hitting one wing of its prey so as not to harm itself on impact. The air pressure from such a dive could possibly damage a bird's lungs, but small bony tubercles on a falcon's nostrils are theorized to guide the powerful airflow away from the nostrils, enabling the bird to breathe more easily while diving by reducing the change in air pressure. To protect their eyes, the falcons use their nictitating membranes (third eyelids) to spread tears and clear debris from their eyes while maintaining vision. A study testing the flight physics of an "ideal falcon" found a theoretical speed limit at 400 km/h (250 mph) for low-altitude flight and 625 km/h (388 mph) for high-altitude flight. In 2005, Ken Franklin recorded a falcon stooping at a top speed of 389 km/h (242 mph).
  The life span of peregrine falcons in the wild is up to 19 years 9 months. Mortality in the first year is 59–70%, declining to 25–32% annually in adults. Apart from such anthropogenic threats as collision with human-made objects, the peregrine may be killed by larger hawks and owls.
  The peregrine falcon is host to a range of parasites and pathogens. It is a vector for Avipoxvirus, Newcastle disease virus, Falconid herpesvirus 1 (and possibly other Herpesviridae), and some mycoses and bacterial infections. Endoparasites include Plasmodium relictum (usually not causing malaria in the peregrine falcon), Strigeidae trematodes, Serratospiculum amaculata (nematode), and tapeworms. Known peregrine falcon ectoparasites are chewing lice, Ceratophyllus garei (a flea), and Hippoboscidae flies (Icosta nigra, Ornithoctona erythrocephala).
  In the Arctic Peregrine falcons chasing away small rodent predators from their nesting territory and Rough-legged Hawks (Buteo lagopus) could use these hot spots as a nesting territory.
caption: Closeup of head showing nostril tubercle
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