How does the brown falcon see?
The brown falcon (Falco berigora) is a bird in the order Falconiformes. Its eyes belong to the vision type Raptor telephoto: 4 cones (violet-sensitive), 2 foveas (deep central + temporal), the highest acuity measured, 35-50 deg binocular.
Measured in this species: sharpness, foveas and night vision. Measured core: measured values on at least 3 of the 6 dials. Every value below carries its evidence level and sources; nothing is typed by hand.
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What stands out
- It has 4 colour receptor classes; people have 3.
- Its sharpest vision resolves 73 cycles per degree: the finest stripe pattern it can tell apart from grey.
- Its eyes cover about 292° around the head, with 37° seen by both eyes at once.
- It stops seeing flicker at 113.25 Hz, against 60 Hz for people in this dataset, so fast motion looks about 1.9 times slower to it.[13][14]
- 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.
| Dial | Value | Evidence | Sources |
|---|---|---|---|
| Colour | Colour receptors 4 receptor classes: 417.5 nm (VS/SWS (violet)), 452 nm (SWS (blue)), 501 nm (MWS (green)), 570 nm (LWS (long)) receptor set of nearest measured relative Anas platyrhynchos (same class Aves) | Group default | [1][2] |
| Sharpness | Acuity 73 cycles per degree median of 1 behavioural rows (method priority rule) | Measured | [3] |
| Field of view | Binocular overlap 37° median of 3 relatives in genus Falco: Falco sparverius, Falco biarmicus, Falco cherrug | Estimated | [4][5][6] |
| Total field of view 292° median total field (measured, or 360 - blind area) of relatives in genus Falco: Falco sparverius | Estimated | [5] | |
| Blind area behind the head 68° | Estimated | [5] | |
| Eye placement lateral | Estimated | [4][5][6] | |
| Sharp zones (foveas) | Number of foveas 2 species-v1.csv text: 2 (central deep + temporal shallow) | Measured (not re-verified) | [7] |
| Fovea type central fovea, temporal | Measured (not re-verified) | [7] | |
| Night vision | Activity pattern diurnal mode of 3 rows (of 3 rows): diurnal; not_nocturnal | Measured (not re-verified) | [8][9][10] |
| Rods vs cones cone-dominated nocturnal -> rod-dominated; crepuscular / cathemeral / mixed -> mixed; diurnal -> cone-dominated | Derived | [8][9][10] | |
| Motion (flicker fusion) | Flicker fusion frequency 113.25 Hz median of 2 relatives in genus Falco: Falco peregrinus, Falco cherrug | Estimated | [11][12] |
Related animals
- American kestrel same vision type
- Saker falcon same vision type
- Chimango caracara same vision type
- Common kestrel same vision type
- Lanner falcon same vision type
- Peregrine falcon same vision type
More birds: all birds with measured vision data.
Sources
- Lind O, Mitkus M, Olsson P, Kelber A. 2014. Ultraviolet vision in birds: the importance of transparent eye media. Proc R Soc B 281:20132209. Table 1. doi.org/10.1098/rspb.2013.2209
- 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
- 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
- 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
- Tyrrell LP, Moore BA, Loftis C, Fernandez-Juricic E 2017 (data 2017). The hawk-eyed songbird: retinal morphology, eye shape, and visual fields of an aerial insectivore. Am Nat 189(6). Dryad doi:10.5061/dryad.n7140.. doi.org/10.1086/691404
- Tyrrell LP, Fernandez-Juricic E 2017. Avian binocular vision: it's not just about what birds can see, it's also about what they can't. PLoS ONE 12(3): e0173235. S1 Table.. doi.org/10.1371/journal.pone.0173235
- species_v1:Reymond 1987
- Light conditions and the evolution of the visual system in birds (figshare dataset, SupplementaryDataset1). doi.org/10.6084/m9.figshare.22116371.v3
- 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
- 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
- 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?