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Short-toed snake-eagle vision: the science and the numbers

Circaetus gallicus · order Accipitriformes · Birds: all the numbers

Its eyes cover about 259° with 17.5° seen by both eyes.[11] Its activity pattern is diurnal.[19][20][21][22]

See it on your photoBack to How does the short-toed snake-eagle see?
  • 259°field of viewEstimated

The short-toed snake-eagle (Circaetus gallicus) 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: 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 the short-toed snake-eagle sees: colour receptors

Short-toed snake-eagle colour receptor peaks, 300 to 700 nmShort-toed snake-eagle: 4 receptor peaks at 405, 449, 504, 567 nm; you: 3 at 421.5, 532, 558.4 nm. ultraviolet300400500600700
Short-toed snake-eagle: 405, 449, 504, 567 nmPeople: 421.5, 532, 558.4 nmWavelength in nanometres

What stands out

  • Its eyes cover about 259° around the head, with 17.5° seen by both eyes at once.
  • 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 short-toed snake-eagle (Circaetus gallicus), 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
84 cycles per degree
median of 8 relatives in family Accipitridae: Aquila audax, Buteo jamaicensis, Gyps fulvus, Gyps indicus, Milvus migrans, Neophron percnopterus
Estimated[6][7][8]Acuity: 63.75 cycles per degree Measured[9][10]
Field of viewBinocular overlap
17.5°
median of 2 rows (eyes-at-rest rows preferred)
Measured[11][12]Binocular overlap: 122.5° Measured[13][14]
Total field of view: 200° Measured (not re-verified)[15]
Blind area behind the head: 160° Derived[15]
Eye placement: frontal Derived[13][14]
Total field of view
259°
rule: total = 360 - blind area
Derived[11]
Blind area behind the head
101°		Measured[11]
Eye placement
lateral
frontal if binocular overlap >= 60 deg, else lateral
Derived[11][12]
Binocular field, vertical extent
80° (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
139° (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)
259° (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
2
retinal topography
Measured (not re-verified)[17]Number of foveas: 1 Measured[18]
Fovea type: fovea Measured[18]
Fovea type
deep central + shallow temporal		Measured (not re-verified)[17]
Night visionActivity pattern
diurnal
mode of 4 rows (of 4 rows): diurnal; not_nocturnal
Measured (not re-verified)[19][20][21][22]Activity pattern: diurnal Measured (not re-verified)[19][23][24][2][25][26][27][22]
Pupil shape: vertical Group default[28][29]
Reflective layer (tapetum): no Measured[30]
Rods vs cones: cone-dominated Derived[19][23][24][2][25][26][27][22]
Night sensitivity (optical, against people): S = 0.93 µm² sr, 1 times people (log10 ratio 0) Derived[31]
Rods vs cones
cone-dominated
nocturnal -> rod-dominated; crepuscular / cathemeral / mixed -> mixed; diurnal -> cone-dominated
Derived[19][20][21][22]
Motion (flicker fusion)Flicker fusion frequency
77.7 Hz
median of 1 relatives in family Accipitridae: Parabuteo unicinctus
Estimated[32]Flicker fusion frequency: 60 Hz Measured[33][34]

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. Caves et al. 2024
  8. Potier et al. 2020
  9. Kirk et al. 2004
  10. Veilleux et al. 2014
  11. Tyrrell et al. 2017
  12. Tyrrell et al. 2017
  13. Heesy 2004
  14. Heffner et al. 1992
  15. Campbell & Green 1965
  16. Martin et al. 1999
  17. Potier et al. 2017
  18. Kopania et al. 2025
  19. Anderson et al. 2017
  20. Light conditions and the evolution of…
  21. Wilman et al. 2014
  22. Moura et al. 2024
  23. Borges et al. 2018
  24. Wilman et al. 2014
  25. Maor et al. 2017
  26. Jones et al. 2009
  27. Schmitz et al. 2011
  28. Banks et al. 2015
  29. Cervino et al. 2021
  30. Guareschi et al. 2025
  31. Brauburger et al. 2026
  32. Lafitte et al. 2022
  33. Healy et al. 2013
  34. 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.