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Thirteen-lined ground squirrel vision: the science and the numbers

Ictidomys tridecemlineatus · order Rodentia · Mammals: all the numbers

The thirteen-lined ground squirrel has 2 colour receptor classes (437 and 517 nm): mainly blues and yellows; reds and greens look alike.[1] Its sharpest vision resolves 4 cycles per degree, against 63.75 for people in this dataset.[5]

See it on your photoBack to How does the thirteen-lined ground squirrel see?
  • 2colour receptor classesMeasured
  • 4cycles per degree (sharpness)Measured

The thirteen-lined ground squirrel (Ictidomys tridecemlineatus) is a mammal in the order Rodentia. Its eyes belong to the vision type Small prey mammal (UV): two or three cone types, often including ultraviolet, low sharpness and a near-panoramic field. Measured in this species: colour, sharpness, 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 thirteen-lined ground squirrel sees: colour receptors

Thirteen-lined ground squirrel colour receptor peaks, 300 to 700 nmThirteen-lined ground squirrel: 2 receptor peaks at 437, 517 nm; you: 3 at 421.5, 532, 558.4 nm. ultraviolet300400500600700
Thirteen-lined ground squirrel: 437, 517 nmPeople: 421.5, 532, 558.4 nmWavelength in nanometres

What stands out

  • It has two colour receptor classes (a dichromat): reds and greens fall on one axis, as in red-green colour blindness in people.
  • Its sharpest vision resolves 4 cycles per degree: the finest stripe pattern it can tell apart from grey.
  • 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 thirteen-lined ground squirrel (Ictidomys tridecemlineatus), catalogue-v1
DialValueEvidenceSourcesPeople
ColourColour receptors
2 receptor classes: 437 nm (VS/SWS (violet)), 517 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)[1][2][3][4]
SharpnessAcuity
4 cycles per degree
median of 1 compilation rows (method priority rule)
Measured[5]Acuity: 63.75 cycles per degree Measured[6][7]
Field of viewBinocular overlap
60°
median of 1 relatives in family Sciuridae: Sciurus carolinensis
Estimated[8]Binocular overlap: 122.5° Measured[8][9]
Total field of view: 200° Measured (not re-verified)[10]
Blind area behind the head: 160° Derived[10]
Eye placement: frontal Derived[8][9]
Sharp zones (foveas)Number of foveas
0
fovea_present / area_centralis_type (retinal topography; count 1 = fovea present, 0 = none)
Measured[11]Number of foveas: 1 Measured[11]
Fovea type: fovea Measured[11]
Fovea type
horizontal streak		Measured[11]
Night visionActivity pattern
diurnal
mode of 9 rows (of 9 rows): diurnal; photopic
Measured (not re-verified)[12][5][13][1][14][15][16][17]Activity pattern: diurnal Measured (not re-verified)[12][5][13][1][14][15][16][17]
Pupil shape: vertical Group default[18][19]
Reflective layer (tapetum): no Measured[20]
Rods vs cones: cone-dominated Derived[12][5][13][1][14][15][16][17]
Rods vs cones
cone-dominated
nocturnal -> rod-dominated; crepuscular / cathemeral / mixed -> mixed; diurnal -> cone-dominated
Derived[12][5][13][1][14][15][16][17]
Motion (flicker fusion)Flicker fusion frequency
103.5 Hz
median of 4 relatives in family Sciuridae: Callospermophilus lateralis, Tamias amoenus, Tamiasciurus hudsonicus, Sciurus vulgaris
Estimated[21][22][23]Flicker fusion frequency: 60 Hz Measured[22][23]

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

Sources

  1. Longcore 2023
  2. Kirwan
  3. Müller et al. 2009
  4. Thermal Activation and Photoactivation of Visual… 2004
  5. Borges et al. 2018
  6. Kirk et al. 2004
  7. Veilleux et al. 2014
  8. Heesy 2004
  9. Heffner et al. 1992
  10. Campbell & Green 1965
  11. Kopania et al. 2025
  12. Anderson et al. 2017
  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. Banks et al. 2015
  19. Cervino et al. 2021
  20. Guareschi et al. 2025
  21. Haarlem et al. 2026
  22. Healy et al. 2013
  23. 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.