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Harris's hawk vision: the science and the numbers

Parabuteo unicinctus · order Accipitriformes · Birds: all the numbers

Their sharpest vision resolves 43.7 cycles per degree, against 63.75 for people in this dataset.[6] Their eyes cover about 277° with 47° seen by both eyes.[9] Harris's hawks stop seeing flicker at 77.7 Hz, against 60 Hz for people.[28]

See it on your photoBack to How do Harris's hawks see?
  • 43.7cycles per degree (sharpness)Measured
  • 277°field of viewEstimated
  • 77.7hertz flicker fusion (motion)Measured

The Harris's hawk (Parabuteo unicinctus) is a bird in the order Accipitriformes. Its eyes belong to the vision type Raptor telephoto: four cone types, two foveas and very high sharpness. Measured in this species: sharpness, field of view, foveas, night vision and motion (flicker fusion). Measured core: measured values on at least 3 of the 6 dials.

This is a simulation built from published eye measurements, not what the animal experiences.

Method: How we know what animals see (the See Like Animals vision engine) · Sources · Last updated . Every value below carries its evidence level and sources; nothing is typed by hand.

What Harris's hawks see: colour receptors

Harris's hawk colour receptor peaks, 300 to 700 nmHarris's hawk: 4 receptor peaks at 405, 449, 504, 567 nm; you: 3 at 421.5, 532, 558.4 nm. ultraviolet300400500600700
Harris's hawk: 405, 449, 504, 567 nmPeople: 421.5, 532, 558.4 nmWavelength in nanometres

What stands out

  • Its sharpest vision resolves 43.7 cycles per degree: the finest stripe pattern it can tell apart from grey.
  • Its eyes cover about 277° around the head, with 47° seen by both eyes at once.
  • It stops seeing flicker at 77.7 Hz, against 60 Hz for people in this dataset, so fast motion looks about 1.3 times slower to it.[29][30]
  • Activity pattern: diurnal.

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. The last column gives the values for people from the same catalogue.

Vision values for the Harris's hawk (Parabuteo unicinctus), catalogue-v1
DialValueEvidenceSourcesPeople
ColourColour receptors
4 receptor classes: 405 nm (VS/SWS (violet)), 449 nm (SWS (blue)), 504 nm (MWS (green)), 567 nm (LWS (long))
receptor set of nearest measured relative Buteo buteo (same family Accipitridae)
Estimated[1][2]Colour receptors: 3 receptor classes: 421.5 nm (VS/SWS (violet)), 532 nm (MWS (green)), 558.4 nm (LWS (long)) Measured (not re-verified)[2][3][4][5]
SharpnessAcuity
43.7 cycles per degree
median of 1 behavioural rows (method priority rule)
Measured[6]Acuity: 63.75 cycles per degree Measured[7][8]
Field of viewBinocular overlap
47°
median of 1 rows (eyes-at-rest rows preferred)
Measured[9]Binocular overlap: 122.5° Measured[10][11]
Total field of view: 200° Measured (not re-verified)[12]
Blind area behind the head: 160° Derived[12]
Eye placement: frontal Derived[10][11]
Total field of view
277°
rule: total = 360 - blind area
Derived[9]
Blind area behind the head
83°		Measured[9]
Eye placement
lateral
frontal if binocular overlap >= 60 deg, else lateral
Derived[9]
Sharp zones (foveas)Number of foveas
2
retinal topography
Measured (not re-verified)[13]Number of foveas: 1 Measured[14]
Fovea type: fovea Measured[14]
Fovea type
deep central + shallow temporal		Measured (not re-verified)[13]
Night visionActivity pattern
diurnal
mode of 5 rows (of 5 rows): diurnal; not_nocturnal; photopic
Measured (not re-verified)[15][16][17][18][19]Activity pattern: diurnal Measured (not re-verified)[20][21][22][2][23][24][18][19]
Pupil shape: vertical Group default[25][26]
Reflective layer (tapetum): no Measured[27]
Rods vs cones: cone-dominated Derived[20][21][22][2][23][24][18][19]
Rods vs cones
cone-dominated
nocturnal -> rod-dominated; crepuscular / cathemeral / mixed -> mixed; diurnal -> cone-dominated
Derived[15][16][17][18][19]
Motion (flicker fusion)Flicker fusion frequency
77.7 Hz
median of 1 bright-light rows (behavioural/whole-eye ERG rows; all rows: [77.7])
Measured[28]Flicker fusion frequency: 60 Hz Measured[29][30]

All birds side by side: Birds: every measurement. Method: how we know what animals see.

Sources

  1. Lind et al. 2014
  2. Longcore 2023
  3. Kirwan
  4. Müller et al. 2009
  5. Thermal Activation and Photoactivation of Visual… 2004
  6. Caves et al. 2018
  7. Kirk et al. 2004
  8. Veilleux et al. 2014
  9. Tyrrell et al. 2017
  10. Heesy 2004
  11. Heffner et al. 1992
  12. Campbell & Green 1965
  13. Potier et al. 2017
  14. Kopania et al. 2025
  15. Light conditions and the evolution of…
  16. Choiniere et al. 2021
  17. Wilman et al. 2014
  18. Schmitz et al. 2011
  19. Moura et al. 2024
  20. Anderson et al. 2017
  21. Borges et al. 2018
  22. Wilman et al. 2014
  23. Maor et al. 2017
  24. Jones et al. 2009
  25. Banks et al. 2015
  26. Cervino et al. 2021
  27. Guareschi et al. 2025
  28. Lafitte et al. 2022
  29. Healy et al. 2013
  30. Inger et al. 2014

Every value cites its sources (all sources). Values were extracted from these works and converted (units, medians, derived values); changes are ours, and the listed sources do not endorse this site. Data: catalogue-v1, built 2026-09-29. Accuracy notes: how accurate is this? Method: how we know.