THE ANIMAL FILES

Peregrine falcon

Falco peregrinus

A hunting dive is not the same measurement as level flight.

The peregrine falcon is often introduced with a speed record, but a more useful account asks what the bird is doing. A steep hunting stoop differs from ordinary travel, while long pointed wings and protective eye membranes support life in flight. Age and sex also change the appearance hidden behind the single name.[1]

Follow the evidence ↓
Peregrine falcon
Image: Georges Lignier (georges.lignier@wanadoo.fr) · Commons · CC BY-SA 3.0
Hunting movement
A steep dive called a stoop[1]
Wing outline
Long and pointed[1]
Sex difference
Females are generally larger[1]

A face pattern with an age context

Adults have a dark facial moustache or malar stripe and typically slate-grey to bluish-dark upperparts. Young birds are browner, with streaked rather than neatly barred underparts. Females are larger than males.[1]

The stoop is a particular task

A peregrine can gain height and dive steeply during a hunting stoop. This is a different movement from steady horizontal travel, so comparing their speeds without naming the flight mode mixes unlike observations.[1]

Eyes need protection as well as information

A nictitating membrane moves across the eye, helping spread tears and clear debris while maintaining vision. Peregrines occur along cliffs, coasts, valleys and in cities, showing that the hunting bird is not restricted to one scenic wilderness image.[1]

A COMMON MIX-UP

Does a famous dive speed describe every kind of flight?

No. A hunting stoop and horizontal flight are different movements. Published extreme speeds also depend on measurement methods and sometimes conflict, so they should not be treated as one typical flying speed.[1]

TRY A LITTLE REASONING

What should accompany a speed claim about an animal?

Reveal the explanation

The movement being measured and the evidence behind the number. For peregrines, identifying whether the bird is diving or travelling horizontally is essential before comparing the claim with another observation or another species.[1]

Sources & editorial notes

Adapted and translated from the cited Wikipedia revisions, with source-linked reasoning. Image credit and licence are listed separately above.

Adapted and translated from Wikipedia contributors; exact revisions are linked below. CC BY-SA 4.0

  1. Wikipedia contributors — Peregrine falcon (fixed revision; adapted and translated)
  2. NCBI Taxonomy — Falco peregrinus (identity and classification)

Last fact check:

One discovery leads to another

American kestrelA small falcon’s fence post can be a hunting platform.Falco sparverius ↗Great titSmall feet can become a food-holding tool.Parus major ↗Common starlingA moving cloud of starlings is built from neighbours reacting to neighbours.Sturnus vulgaris ↗