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Azara's owl monkey vision: the science and the numbers

Aotus azarae · order Primates · Mammals: all the numbers

The Azara's owl monkey has one cone type, so no colour vision in daylight.[1] Its sharpest vision resolves 8.5 cycles per degree, against 63.75 for people in this dataset.[6]

See it on your photoBack to How does the Azara's owl monkey see?
  • 1colour receptor classMeasured
  • 8.5cycles per degree (sharpness)Measured

The Azara's owl monkey (Aotus azarae) is a mammal in the order Primates. Its eyes belong to the vision type Day dichromat mammal: two cone types (blue and yellow, so reds and greens merge), moderate sharpness and a horizontal band of sharp vision. Measured in this species: colour, sharpness 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 Azara's owl monkey sees: colour receptors

Azara's owl monkey colour receptor peaks, 300 to 700 nmAzara's owl monkey: 1 receptor peak at 539 nm; you: 3 at 421.5, 532, 558.4 nm. ultraviolet300400500600700
Azara's owl monkey: 539 nmPeople: 421.5, 532, 558.4 nmWavelength in nanometres

What stands out

  • It has one receptor class for colour, so it sees brightness but no hue.
  • Its sharpest vision resolves 8.5 cycles per degree: the finest stripe pattern it can tell apart from grey.
  • 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 Azara's owl monkey (Aotus azarae), catalogue-v1
DialValueEvidenceSourcesPeople
ColourColour receptors
1 receptor class: 539 nm (MWS (green))
measured in this species
Measured[1]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
8.5 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
138°
median of 1 relatives in genus Aotus: Aotus trivirgatus
Estimated[9]Binocular overlap: 122.5° Measured[9][10]
Total field of view: 200° Measured (not re-verified)[11]
Blind area behind the head: 160° Derived[11]
Eye placement: frontal Derived[9][10]
Total field of view
200°
median species-v1 total field of order Primates: Homo sapiens
Group default[11]
Sharp zones (foveas)Number of foveas
1
median of 1 relatives in genus Aotus: Aotus trivirgatus
Estimated[12]Number of foveas: 1 Measured[12]
Fovea type: fovea Measured[12]
Fovea type
fovea		Estimated[12]
Night visionActivity pattern
nocturnal
mode of 7 rows (of 7 rows): cathemeral; nocturnal; scotopic
Measured (not re-verified)[13][14][15][16][17]Activity pattern: diurnal Measured (not re-verified)[18][19][13][2][14][15][16][17]
Pupil shape: vertical Group default[20][21]
Reflective layer (tapetum): no Measured[22]
Rods vs cones: cone-dominated Derived[18][19][13][2][14][15][16][17]
Rods vs cones
rod-dominated
nocturnal -> rod-dominated; crepuscular / cathemeral / mixed -> mixed; diurnal -> cone-dominated
Derived[13][14][15][16][17]
Motion (flicker fusion)Flicker fusion frequency
69 Hz
median of 3 relatives in order Primates: Macaca mulatta, Macaca nemestrina, Homo sapiens
Group default[23][24][25]Flicker fusion frequency: 60 Hz Measured[23][24]

All mammals side by side: Mammals: every measurement. Method: how we know what animals see.

Sources

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

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.