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Tawny owl vision: the science and the numbers

Strix aluco · order Strigiformes · Birds: all the numbers

Tawny owls have four colour channels, including violet (420, 463, 530 and 555 nm).[1][2][3] Their sharpest vision resolves 9.55 cycles per degree, against 63.75 for people in this dataset.[7][8] Their eyes cover about 201° with 48° seen by both eyes.[15]

See it on your photoBack to How do tawny owls see?
  • 4colour receptor classesMeasured
  • 9.55cycles per degree (sharpness)Measured
  • 201°field of viewMeasured*

The tawny owl (Strix aluco) is a bird in the order Strigiformes. Its eyes belong to the vision type Owl and night bird: rod-dominated eyes built for dim light, with low sharpness. Measured in this species: colour, sharpness, field of view, foveas and night vision. 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 tawny owls see: colour receptors

Tawny owl colour receptor peaks, 300 to 700 nmTawny owl: 4 receptor peaks at 420, 463, 530, 555 nm; you: 3 at 421.5, 532, 558.4 nm. ultraviolet300400500600700
Tawny owl: 420, 463, 530, 555 nmPeople: 421.5, 532, 558.4 nmWavelength in nanometres

What stands out

  • It has 4 colour receptor classes; people have 3.
  • Its sharpest vision resolves 9.55 cycles per degree: the finest stripe pattern it can tell apart from grey.
  • Its eyes cover about 201° around the head, with 48° seen by both eyes at once.
  • Activity pattern: nocturnal.

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 tawny owl (Strix aluco), catalogue-v1
DialValueEvidenceSourcesPeople
ColourColour receptors
4 receptor classes: 420 nm (VS/SWS (violet)), 463 nm (SWS (blue)), 530 nm (MWS (green)), 555 nm (LWS (long))
measured in this species
Measured[1][2][3]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][4][5][6]
SharpnessAcuity
9.55 cycles per degree
median of 2 behavioural rows (method priority rule)
Measured[7][8]Acuity: 63.75 cycles per degree Measured[9][10]
Field of viewBinocular overlap
48°
median of 1 rows (eyes-at-rest rows preferred)
Measured[11]Binocular overlap: 122.5° Measured[12][13]
Total field of view: 200° Measured (not re-verified)[14]
Blind area behind the head: 160° Derived[14]
Eye placement: frontal Derived[12][13]
Total field of view
201°
species-v1.csv
Measured (not re-verified)[15]
Blind area behind the head
159°
blind area = 360 - total field
Derived[15]
Eye placement
lateral
frontal if binocular overlap >= 60 deg, else lateral
Derived[11]
Binocular field, vertical extent
70° (approximate); approximately horizontal plane; eyes in relaxed (resting) position; head in typical posture for the species; alert live birds		Measured[16]
Field of one eye
124° (approximate); approximately horizontal plane; eyes in relaxed (resting) position; head in typical posture for the species; alert live birds		Measured[16]
Total field (published value)
210° (approximate); approximately horizontal plane; eyes in relaxed (resting) position; head in typical posture for the species; alert live birds		Measured[16]
Sharp zones (foveas)Number of foveas
1
species-v1.csv text: 1 (temporal shallow fovea)
Measured[17][15]Number of foveas: 1 Measured[18]
Fovea type: fovea Measured[18]
Fovea type
temporal		Measured[17][15]
Night visionActivity pattern
nocturnal
mode of 7 rows (of 7 rows): diurnal; mesopic; nocturnal
Measured (not re-verified)[19][20][21][22][2][23][24]Activity pattern: diurnal Measured (not re-verified)[19][25][26][2][27][28][23][24]
Pupil shape: vertical Group default[29][30]
Reflective layer (tapetum): no Measured[31]
Rods vs cones: cone-dominated Derived[19][25][26][2][27][28][23][24]
Night sensitivity (optical, against people): S = 0.93 µm² sr, 1 times people (log10 ratio 0) Derived[32]
Reflective layer (tapetum)
no		Measured (not re-verified)[33]
Rods vs cones
rod-dominated
nocturnal -> rod-dominated; crepuscular / cathemeral / mixed -> mixed; diurnal -> cone-dominated
Derived[19][20][21][22][2][23][24]
Motion (flicker fusion)Flicker fusion frequency
50 Hz
median of 3 relatives in family Strigidae: Bubo virginianus, Athene noctua, Asio flammeus
Estimated[34][35]Flicker fusion frequency: 60 Hz Measured[34][36]

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. VPOD in-vivo (MSP / single-cell) lambda… 2025
  4. Kirwan
  5. Müller et al. 2009
  6. Thermal Activation and Photoactivation of Visual… 2004
  7. Caves et al. 2018
  8. Caves et al. 2024
  9. Kirk et al. 2004
  10. Veilleux et al. 2014
  11. Potier et al. 2023
  12. Heesy 2004
  13. Heffner et al. 1992
  14. Campbell & Green 1965
  15. Martin 1984
  16. Martin et al. 1999
  17. Shukla et al. 2026
  18. Kopania et al. 2025
  19. Anderson et al. 2017
  20. Light conditions and the evolution of…
  21. Choiniere et al. 2021
  22. Wilman et al. 2014
  23. Schmitz et al. 2011
  24. Moura et al. 2024
  25. Borges et al. 2018
  26. Wilman et al. 2014
  27. Maor et al. 2017
  28. Jones et al. 2009
  29. Banks et al. 2015
  30. Cervino et al. 2021
  31. Guareschi et al. 2025
  32. Brauburger et al. 2026
  33. Martin 1977
  34. Healy et al. 2013
  35. Lafitte et al. 2022
  36. 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.