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How does the American kestrel see?

The American kestrel (Falco sparverius) is a bird in the order Falconiformes. Its eyes belong to the vision type Raptor telephoto: 4 cones (violet-sensitive), 2 foveas (deep central + temporal), the highest acuity measured, 35-50 deg binocular.

Measured in this species: sharpness, field of view, foveas and night vision. Measured core: measured values on at least 3 of the 6 dials. Every value below carries its evidence level and sources; nothing is typed by hand.

Sample scene drawn in code: a face with red lips, a green shirt, red and green apples, flowers and a colour strip, as a person sees it.
The sample scene as a person sees it.
The same sample scene rendered by the See Like Animals engine for the American kestrel's eyes, using the values in the table below.
The same scene rendered for the American kestrel (60° field of view, daylight).
See your photo as the American kestrelThis species is part of the full catalogue in the tool (full unlock). Your photo stays on your device.

What stands out

The six dials

Evidence levels: how the tiers work. "Measured" means a value measured in this species; "Estimated" values come from a close relative or an eye-size formula.

Vision values for the American kestrel (Falco sparverius), catalogue-v1
DialValueEvidenceSources
ColourColour receptors
4 receptor classes: 417.5 nm (VS/SWS (violet)), 452 nm (SWS (blue)), 501 nm (MWS (green)), 570 nm (LWS (long))
receptor set of nearest measured relative Anas platyrhynchos (same class Aves)
Group default[1][2]
SharpnessAcuity
30.85 cycles per degree
median of 2 behavioural rows (method priority rule)
Measured[3][4]
Field of viewBinocular overlap
27.5°
median of 2 rows (eyes-at-rest rows preferred)
Measured[5][6]
Total field of view
292°
rule: total = 360 - blind area
Derived[5]
Blind area behind the head
68°		Measured[5]
Eye placement
lateral
frontal if binocular overlap >= 60 deg, else lateral
Derived[5][6]
Sharp zones (foveas)Number of foveas
2
species-v1.csv text: 2 (central deep + temporal shallow)
Measured[7][8]
Fovea type
central fovea, temporal		Measured[7][8]
Night visionActivity pattern
diurnal
mode of 6 rows (of 6 rows): diurnal; not_nocturnal
Measured (not re-verified)[9][10][11][12][13][14]
Rods vs cones
cone-dominated
nocturnal -> rod-dominated; crepuscular / cathemeral / mixed -> mixed; diurnal -> cone-dominated
Derived[9][10][11][12][13][14]
Motion (flicker fusion)Flicker fusion frequency
113.25 Hz
median of 2 relatives in genus Falco: Falco peregrinus, Falco cherrug
Estimated[15][16]

Related animals

More birds: all birds with measured vision data.

Sources

  1. Lind O, Mitkus M, Olsson P, Kelber A. 2014. Ultraviolet vision in birds: the importance of transparent eye media. Proc R Soc B 281:20132209. Table 1. doi.org/10.1098/rspb.2013.2209
  2. Longcore T. 2023. A compendium of photopigment peak sensitivities and visual spectral response curves of terrestrial wildlife to guide design of outdoor nighttime lighting. Basic Appl Ecol 73:40-50. doi:10.1016/j.baae.2023.09.002. doi.org/10.5281/zenodo.8432720
  3. Caves EM, Brandley NC, Johnsen S (2018) Visual acuity and the evolution of signals. Trends Ecol Evol 33:358-372. Supplementary Tables S1-S3.. doi.org/10.1016/j.tree.2018.03.001
  4. Caves EM, Fernandez-Juricic E, Kelley LA (2024) Ecological and morphological correlates of visual acuity in birds. J Exp Biol 227(2): jeb246063. Supplementary Table S1.. doi.org/10.1242/jeb.246063
  5. Tyrrell LP, Moore BA, Loftis C, Fernandez-Juricic E 2017 (data 2017). The hawk-eyed songbird: retinal morphology, eye shape, and visual fields of an aerial insectivore. Am Nat 189(6). Dryad doi:10.5061/dryad.n7140.. doi.org/10.1086/691404
  6. Tyrrell LP, Fernandez-Juricic E 2017. Avian binocular vision: it's not just about what birds can see, it's also about what they can't. PLoS ONE 12(3): e0173235. S1 Table.. doi.org/10.1371/journal.pone.0173235
  7. Rasys AM, Wegerski A, Trainor PA, Hufnagel RB, Menke DB, Lauderdale JD. 2024. Dynamic changes in ocular shape during human development and its implications for retina fovea formation. BioEssays : news and reviews in molecular, cellular and developmental biology 46(1):e2300054. doi.org/10.1002/bies.202300054
  8. species_v1:Potier et al. 2017 (review, Front Neurosci?)
  9. Angielczyk KD, Schmitz L 2014. Nocturnality in synapsids predates the origin of mammals by over 100 million years. Proc R Soc B 281: 20141642. Dryad doi:10.5061/dryad.1v8kj.. doi.org/10.1098/rspb.2014.1642
  10. Light conditions and the evolution of the visual system in birds (figshare dataset, SupplementaryDataset1). doi.org/10.6084/m9.figshare.22116371.v3
  11. Choiniere JN, Neenan JM, Schmitz L, Ford DP, Chapelle KEJ, Balanoff AM, Sipla JS, Georgi JA, Walsh SA, Norell MA, Xu X, Clark JM, Benson RBJ. 2021. Evolution of vision and hearing modalities in theropod dinosaurs. Science 372:610-613. doi:10.1126/science.abe7941. Data: https://osf.io/teq73/. doi.org/10.1126/science.abe7941
  12. Wilman H, Belmaker J, Simpson J, de la Rosa C, Rivadeneira MM, Jetz W. 2014. EltonTraits 1.0: species-level foraging attributes of the world's birds and mammals. Ecology 95:2027. BirdFuncDat.txt. doi.org/10.6084/m9.figshare.3559887.v1
  13. Schmitz & Motani 2011. Nocturnality in dinosaurs inferred from scleral ring and orbit morphology. Science 332:705. Comparative data redeposited in Xing et al. 2020 supplementary information (Zenodo).. doi.org/10.5281/zenodo.3591994
  14. Moura et al. 2024. A phylogeny-informed characterisation of global tetrapod traits addresses data gaps and biases. PLoS Biol 22:e3002658. TetrapodTraits v3.0.1.. doi.org/10.5281/zenodo.22536349
  15. Haarlem CS, Hynes C, Jackson AL, Mitchell KJ, O'Connell RG, Healy K. 2026. Pace of ecology drives the tempo of visual perception across the animal kingdom. Nature Ecology & Evolution (doi:10.1038/s41559-026-02994-7). Figshare dataset 10.6084/m9.figshare.30556475. doi.org/10.6084/m9.figshare.30556475
  16. Lafitte A, Sordello R, Legrand M, Nicolas V, Obein G, Reyjol Y. 2022. A flashing light may not be that flashy: A systematic review on critical fusion frequencies. PLoS ONE 17(12): e0279718. S10 File (CFF database). doi.org/10.1371/journal.pone.0279718
  17. Healy K, McNally L, Ruxton GD, Cooper N, Jackson AL. 2013. Metabolic rate and body size are linked with perception of temporal information. Animal Behaviour 86:685-696. Table 1. doi.org/10.1016/j.anbehav.2013.06.018
  18. Inger R, Bennie J, Davies TW, Gaston KJ. 2014. Potential biological and ecological effects of flickering artificial light. PLoS ONE 9(5): e98631. Table 3. doi.org/10.1371/journal.pone.0098631

Every value cites its sources (all sources). Data: catalogue-v1, built 2026-09-29. Accuracy notes: how accurate is this?