How does the island fox see?
The island fox (Urocyon littoralis) is a mammal in the order Carnivora. Its eyes belong to the vision type Day dichromat mammal.
Measured in this species: colour and night vision. Measured colour or sharpness: a measured receptor set or acuity in this species; other dials come from relatives or group defaults. Every value below carries its evidence level and sources; nothing is typed by hand.
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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 14.57 cycles per degree: the finest stripe pattern it can tell apart from grey.
- Its eyes cover about 250° around the head, with 97° seen by both eyes at once.
- It stops seeing flicker at 80.75 Hz, against 60 Hz for people in this dataset, so fast motion looks about 1.3 times slower to it.[13][14]
- Activity pattern: cathemeral.
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.
| Dial | Value | Evidence | Sources |
|---|---|---|---|
| Colour | Colour receptors 2 receptor classes: 432 nm (VS/SWS (violet)), 555 nm (LWS (long)) measured in this species | Measured | [1] |
| Sharpness | Acuity 14.57 cycles per degree median of 1 relatives in family Canidae: Canis lupus | Estimated | [2] |
| Field of view | Binocular overlap 97° median of 1 relatives in family Canidae: Canis lupus | Estimated | [3] |
| Total field of view 250° median species-v1 total field of family Canidae: Canis familiaris | Estimated | [4] | |
| Sharp zones (foveas) | Number of foveas 0 median of 2 relatives in family Canidae: Canis lupus, Vulpes lagopus | Estimated | [5] |
| Fovea type area centralis, horizontal streak | Estimated | [5] | |
| Night vision | Activity pattern cathemeral mode of 6 rows (of 7 rows): cathemeral; cathemeral (polyphasic); mesopic; mixed (nocturnal/crepuscular, cathemeral, crepuscular or diurnal/crepuscular); nocturnal/crepuscular | Measured (not re-verified) | [6][7][1][8][9][10][11] |
| Rods vs cones mixed nocturnal -> rod-dominated; crepuscular / cathemeral / mixed -> mixed; diurnal -> cone-dominated | Derived | [6][7][1][8][9][10][11] | |
| Motion (flicker fusion) | Flicker fusion frequency 80.75 Hz median of 2 relatives in family Canidae: Canis lupus, Canis familiaris | Estimated | [12][13][14] |
Related animals
- Dog same vision type
- Grey wolf same vision type
- Arctic fox same vision type
- Spotted hyena same vision type
- Kinkajou same vision type
- Meerkat same vision type
More mammals: all mammals with measured vision data.
Sources
- Longcore T. 2023. A compendium of photopigment peak sensitivities and visual spectral response curves of terrestrial wildlife to guide design of outdoor nighttime lighting. Basic Appl Ecol 73:40-50. doi:10.1016/j.baae.2023.09.002. doi.org/10.5281/zenodo.8432720
- Veilleux CC, Kirk EC 2014. Visual acuity in mammals. Brain Behav Evol 83:43, Supplementary Table 1 (cleaned CSV in Evo-M1-Trait-Data). doi.org/10.1159/000357830
- Heesy CP 2004. On the relationship between orbit orientation and binocular visual field overlap in mammals. Anat Rec 281A:1104, Table 1. doi.org/10.1002/ar.a.20116
- species_v1:Miller & Murphy 1995
- Kopania EEK, Clark NL. 2025. Mammalian retinal specializations for high acuity vision evolve in response to both foraging strategies and morphological constraints. Evolution Letters 9: qrae072. Supplementary Tables S1-S2.. doi.org/10.1093/evlett/qrae072
- Banks MS, Sprague WW, Schmoll J, Parnell JAQ, Love GD. 2015. Science Advances 1:e1500391. doi.org/10.1126/sciadv.1500391
- Wilman et al. 2014 EltonTraits 1.0, MamFuncDat.txt. doi.org/10.6084/m9.figshare.3559887.v1
- Maor R, Dayan T, Ferguson-Gow H, Jones KE. 2017. Temporal niche expansion in mammals from a nocturnal ancestor after dinosaur extinction. Nature Ecology & Evolution 1:1889-1895. Supplementary Table 1. doi.org/10.1038/s41559-017-0366-5
- Jones KE et al. 2009. PanTHERIA: a species-level database of life history, ecology, and geography of extant and recently extinct mammals. Ecology 90:2648. Ecological Archives E090-184. doi.org/10.1890/08-1494.1
- Schmitz L, Motani R. 2011. Science 332:705-708, SOM. doi.org/10.1126/science.1200043
- Moura et al. 2024. A phylogeny-informed characterisation of global tetrapod traits addresses data gaps and biases. PLoS Biol 22:e3002658. TetrapodTraits v3.0.1.. doi.org/10.5281/zenodo.22536349
- Haarlem CS, Hynes C, Jackson AL, Mitchell KJ, O'Connell RG, Healy K. 2026. Pace of ecology drives the tempo of visual perception across the animal kingdom. Nature Ecology & Evolution (doi:10.1038/s41559-026-02994-7). Figshare dataset 10.6084/m9.figshare.30556475. doi.org/10.6084/m9.figshare.30556475
- Healy K, McNally L, Ruxton GD, Cooper N, Jackson AL. 2013. Metabolic rate and body size are linked with perception of temporal information. Animal Behaviour 86:685-696. Table 1. doi.org/10.1016/j.anbehav.2013.06.018
- Inger R, Bennie J, Davies TW, Gaston KJ. 2014. Potential biological and ecological effects of flickering artificial light. PLoS ONE 9(5): e98631. Table 3. doi.org/10.1371/journal.pone.0098631
Every value cites its sources (all sources). Data: catalogue-v1, built 2026-09-29. Accuracy notes: how accurate is this?