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Brown-headed cowbird vision: the science and the numbers

Molothrus ater · order Passeriformes · Birds: all the numbers

Its sharpest vision resolves 5.1 cycles per degree, against 63.75 for people in this dataset.[6] The brown-headed cowbird stops seeing flicker at 114.7 Hz, against 60 Hz for people.[27]

See it on your photoBack to How does the brown-headed cowbird see?
  • 5.1cycles per degree (sharpness)Measured
  • 114.7hertz flicker fusion (motion)Measured

The brown-headed cowbird (Molothrus ater) is a bird in the order Passeriformes. Its eyes belong to the vision type UV songbird, parrot and hummingbird: four cone types including a true ultraviolet cone, coloured oil droplets and fast motion vision. Measured in this species: sharpness, 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 the brown-headed cowbird sees: colour receptors

Brown-headed cowbird colour receptor peaks, 300 to 700 nmBrown-headed cowbird: 4 receptor peaks at 367.5, 443, 502.5, 570 nm; you: 3 at 421.5, 532, 558.4 nm. ultraviolet300400500600700
Brown-headed cowbird: 367.5, 443, 502.5, 570 nmPeople: 421.5, 532, 558.4 nmWavelength in nanometres

What stands out

  • Its sharpest vision resolves 5.1 cycles per degree: the finest stripe pattern it can tell apart from grey.
  • It stops seeing flicker at 114.7 Hz, against 60 Hz for people in this dataset, so fast motion looks about 1.9 times slower to it.[28][29]
  • 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 brown-headed cowbird (Molothrus ater), catalogue-v1
DialValueEvidenceSourcesPeople
ColourColour receptors
4 receptor classes: 367.5 nm (UVS), 443 nm (SWS (blue)), 502.5 nm (MWS (green)), 570 nm (LWS (long))
receptor set of nearest measured relative Serinus canaria (same order Passeriformes)
Group default[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)[1][3][4][5]
Ultraviolet
yes: at least one receptor peaks in the ultraviolet		Group default
SharpnessAcuity
5.1 cycles per degree
median of 1 anatomical-ganglion rows (method priority rule)
Measured[6]Acuity: 63.75 cycles per degree Measured[7][8]
Field of viewBinocular overlap
28°
median of 1 relatives in family Icteridae: Sturnella magna
Estimated[9][10]Binocular overlap: 122.5° Measured[11][12]
Total field of view: 200° Measured (not re-verified)[13]
Blind area behind the head: 160° Derived[13]
Eye placement: frontal Derived[11][12]
Total field of view
327°
median total field (measured, or 360 - blind area) of relatives in family Icteridae: Sturnella magna
Estimated[9]
Blind area behind the head
33°		Estimated[9]
Eye placement
lateral		Estimated[9][10]
Sharp zones (foveas)Number of foveas
1
retinal topography
Measured (not re-verified)[14]Number of foveas: 1 Measured[15]
Fovea type: fovea Measured[15]
Fovea type
single central fovea (displaced dorso-temporally from retinal centre)		Measured (not re-verified)[14]
Night visionActivity pattern
diurnal
mode of 2 rows (of 2 rows): diurnal; not_nocturnal
Measured (not re-verified)[16][17]Activity pattern: diurnal Measured (not re-verified)[18][19][20][1][21][22][23][17]
Pupil shape: vertical Group default[24][25]
Reflective layer (tapetum): no Measured[26]
Rods vs cones: cone-dominated Derived[18][19][20][1][21][22][23][17]
Rods vs cones
cone-dominated
nocturnal -> rod-dominated; crepuscular / cathemeral / mixed -> mixed; diurnal -> cone-dominated
Derived[16][17]
Motion (flicker fusion)Flicker fusion frequency
114.7 Hz
median of 1 bright-light rows (behavioural/whole-eye ERG rows; all rows: [114.7])
Measured[27]Flicker fusion frequency: 60 Hz Measured[28][29]

Other senses

  • magnetoreception: NOT RENDERED (no agreed visual percept) (Group default)

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

Sources

  1. Longcore 2023
  2. VPOD in-vivo (MSP / single-cell) lambda… 2025
  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. Tyrrell et al. 2017
  11. Heesy 2004
  12. Heffner et al. 1992
  13. Campbell & Green 1965
  14. Moore et al. 2017
  15. Kopania et al. 2025
  16. Wilman et al. 2014
  17. Moura et al. 2024
  18. Anderson et al. 2017
  19. Borges et al. 2018
  20. Wilman et al. 2014
  21. Maor et al. 2017
  22. Jones et al. 2009
  23. Schmitz et al. 2011
  24. Banks et al. 2015
  25. Cervino et al. 2021
  26. Guareschi et al. 2025
  27. Lafitte et al. 2022
  28. Healy et al. 2013
  29. 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.