House finch vision: the science and the numbers
Haemorhous mexicanus · order Passeriformes · Birds: all the numbers
Its sharpest vision resolves 4.69 cycles per degree, against 63.75 for people in this dataset.[6] Its activity pattern is diurnal.[15][16][17][18]
- 4.69cycles per degree (sharpness)Measured
The house finch (Haemorhous mexicanus) 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 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.
What the house finch sees: colour receptors
What stands out
- Its sharpest vision resolves 4.69 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.
| Dial | Value | Evidence | Sources | People |
|---|---|---|---|---|
| Colour | Colour 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 family Fringillidae) | 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)[1][3][4][5] |
| Ultraviolet yes: at least one receptor peaks in the ultraviolet | Estimated | |||
| Sharpness | Acuity 4.69 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 view | Binocular overlap 46° median of 1 relatives in family Fringillidae: Spinus tristis | Estimated | [9] | Binocular overlap: 122.5° Measured[10][11] Total field of view: 200° Measured (not re-verified)[12] Blind area behind the head: 160° Derived[12] Eye placement: frontal Derived[10][11] |
| Total field of view 315° median total field (measured, or 360 - blind area) of relatives in family Fringillidae: Spinus tristis | Estimated | [9] | ||
| Sharp zones (foveas) | Number of foveas 1 retinal topography | Measured (not re-verified) | [13] | Number of foveas: 1 Measured[14] Fovea type: fovea Measured[14] |
| Fovea type single central fovea (displaced dorso-temporally from retinal centre) | Measured (not re-verified) | [13] | ||
| Night vision | Activity pattern diurnal mode of 4 rows (of 4 rows): diurnal; not_nocturnal; photopic | Measured (not re-verified) | [15][16][17][18] | Activity pattern: diurnal Measured (not re-verified)[19][20][21][1][22][23][17][18] Pupil shape: vertical Group default[24][25] Reflective layer (tapetum): no Measured[26] Rods vs cones: cone-dominated Derived[19][20][21][1][22][23][17][18] |
| Rods vs cones cone-dominated nocturnal -> rod-dominated; crepuscular / cathemeral / mixed -> mixed; diurnal -> cone-dominated | Derived | [15][16][17][18] | ||
| Motion (flicker fusion) | Flicker fusion frequency 100 Hz median of 7 relatives in order Passeriformes: Passer domesticus, Taeniopygia guttata, Molothrus ater, Sturnus vulgaris, Cyanistes caeruleus, Ficedula albicollis | Group default | [27][28][29][30] | 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
- Longcore 2023
- VPOD in-vivo (MSP / single-cell) lambda… 2025
- Kirwan
- Müller et al. 2009
- Thermal Activation and Photoactivation of Visual… 2004
- Caves et al. 2018
- Kirk et al. 2004
- Veilleux et al. 2014
- Tyrrell et al. 2017
- Heesy 2004
- Heffner et al. 1992
- Campbell & Green 1965
- Moore et al. 2017
- Kopania et al. 2025
- Light conditions and the evolution of…
- Wilman et al. 2014
- Schmitz et al. 2011
- Moura et al. 2024
- Anderson et al. 2017
- Borges et al. 2018
- Wilman et al. 2014
- Maor et al. 2017
- Jones et al. 2009
- Banks et al. 2015
- Cervino et al. 2021
- Guareschi et al. 2025
- Boström et al. 2016
- Healy et al. 2013
- Inger et al. 2014
- 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.