How does the Cape eagle-owl see?
The Cape eagle-owl (Bubo capensis) is a bird in the order Strigiformes. Its eyes belong to the vision type Owl and night bird.
Measured in this species: field of view and night vision. One measured dial: a value other than colour or sharpness is measured in this species; colour and sharpness are not measured here. Every value below carries its evidence level and sources; nothing is typed by hand.
See your photo as the Cape eagle-owlThis species is part of the full catalogue in the tool (full unlock). Your photo stays on your device.
What stands out
- It has one receptor class for colour, so it sees brightness but no hue.
- Its sharpest vision resolves 22.71 cycles per degree: the finest stripe pattern it can tell apart from grey.
- Its eyes cover about 201° around the head, with 44° seen by both eyes at once.
- It stops seeing flicker at 40 Hz, against 60 Hz for people in this dataset, so fast motion looks choppier to it.[14][15]
- 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.
| Dial | Value | Evidence | Sources |
|---|---|---|---|
| Colour | Colour receptors 1 receptor class: 555 nm (LWS (long)) receptor set of nearest measured relative Bubo virginianus (same genus Bubo) | Estimated | [1][2] |
| Sharpness | Acuity 22.71 cycles per degree median of 2 relatives in genus Bubo: Bubo virginianus, Bubo scandiacus | Estimated | [3][4][5] |
| Field of view | Binocular overlap 44° median of 1 rows (eyes-at-rest rows preferred) | Measured | [6] |
| Total field of view 201° median species-v1 total field of family Strigidae: Strix aluco | Estimated | [7] | |
| Sharp zones (foveas) | Number of foveas 1 median of 48 relatives in class Aves: Branta canadensis, Cardinalis cardinalis, Passerina cyanea, Zenaida macroura, Cyanocitta cristata, Junco hyemalis | Group default | [8][9][10] |
| Fovea type single central fovea (displaced dorso-temporally from retinal centre) | Group default | [8][9][10] | |
| Night vision | Activity pattern nocturnal mode of 2 rows (of 2 rows): nocturnal | Measured (not re-verified) | [11][12] |
| Rods vs cones rod-dominated nocturnal -> rod-dominated; crepuscular / cathemeral / mixed -> mixed; diurnal -> cone-dominated | Derived | [11][12] | |
| Motion (flicker fusion) | Flicker fusion frequency 40 Hz median of 1 relatives in genus Bubo: Bubo virginianus | Estimated | [13] |
Related animals
- Great horned owl same vision type
- Tawny owl same vision type
- Barn owl same vision type
- Little owl same vision type
- Great grey owl same vision type
- Snowy owl same vision type
More birds: all birds 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
- VPOD in-vivo (MSP / single-cell) lambda max compendium, file scp_cleaned.csv, VPOD GitHub (Frazer et al. 2025 bioRxiv 10.1101/2025.08.22.671864). github.com/VisualPhysiologyDB/visual-physiology-opsin-db/tree/main/scripts_n_notebooks/vpod_ML_workflows/mine_n_match/data_sources/lmax/vpod
- Caves EM, Brandley NC, Johnsen S (2018) Visual acuity and the evolution of signals. Trends Ecol Evol 33:358-372. Supplementary Tables S1-S3.. doi.org/10.1016/j.tree.2018.03.001
- Caves EM, Fernandez-Juricic E, Kelley LA (2024) Ecological and morphological correlates of visual acuity in birds. J Exp Biol 227(2): jeb246063. Supplementary Table S1.. doi.org/10.1242/jeb.246063
- Potier S, Mitkus M, Kelber A (2020) Visual adaptations of diurnal and nocturnal raptors. Semin Cell Dev Biol 106:156-164. Table 1.. doi.org/10.1016/j.semcdb.2020.05.004
- Potier S, Roulin A, Martin GR, Portugal SJ, Bonhomme V, Bouchet T, de Romans R, Meyrier E, Kelber A. 2023. Binocular field configuration in owls: the role of foraging ecology. Proc R Soc B 290: 20230664. Data figshare.. doi.org/10.1098/rspb.2023.0664
- species_v1:Martin 1984
- Moore BA, Tyrrell LP, Pita D, Bininda-Emonds ORP, Fernandez-Juricic E 2017. Does retinal configuration make the head and eyes of foveate birds move? Sci Rep 7: 38406. Appendix 1.. doi.org/10.1038/srep38406
- Potier S, Mitkus M, Bonadonna F, Duriez O, Isard P-F, Dulaurent T, Mentek M, Kelber A 2017. Eye size, fovea, and foraging ecology in accipitriform raptors. Brain Behav Evol 90: 232-242. Supplementary material (Tables S1, S2).. doi.org/10.1159/000479783
- Rodrigues T, Matter MM, Chiodini A, et al. 2026. Foveal vision in fast-flying birds hunting on the wing. bioRxiv 2026.06.05.730304. doi.org/10.64898/2026.06.05.730304
- Wilman H, Belmaker J, Simpson J, de la Rosa C, Rivadeneira MM, Jetz W. 2014. EltonTraits 1.0: species-level foraging attributes of the world's birds and mammals. Ecology 95:2027. BirdFuncDat.txt. doi.org/10.6084/m9.figshare.3559887.v1
- 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
- Lafitte A, Sordello R, Legrand M, Nicolas V, Obein G, Reyjol Y. 2022. A flashing light may not be that flashy: A systematic review on critical fusion frequencies. PLoS ONE 17(12): e0279718. S10 File (CFF database). doi.org/10.1371/journal.pone.0279718
- 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?