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How does the greater rhea see?

The greater rhea (Rhea americana) is a bird in the order Rheiformes. Its eyes belong to the vision type Panoramic grain-eater and wader.

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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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.

Vision values for the greater rhea (Rhea americana), catalogue-v1
DialValueEvidenceSources
ColourColour receptors
4 receptor classes: 405 nm (VS/SWS (violet)), 446 nm (SWS (blue)), 506 nm (MWS (green)), 570 nm (LWS (long))
measured in this species
Measured[1][2]
SharpnessAcuity
31.82 cycles per degree
allometry (Aves): log10(acuity_cpd) = intercept + slope * log10(eye_axial_length_mm); slope 0.9017, intercept 0.1397, R2 0.453, n 99 (fitted in this script; fitted range [4.36, 39.81] mm); eye_axial_length_mm 32.4775 mm
Estimated[3][4]
Field of viewBinocular overlap
27.5°
median of 133 relatives in class Aves: Accipiter cooperii, Spatula clypeata, Mareca penelope, Anas platyrhynchos, Ardeola ralloides, Baeolophus bicolor
Group default[5][6][7][8][9][10][11][12][13]
Total field of view
338°
group default: median total field of vision type V10 within phylum Chordata in species-v1: Columba livia, Scolopax minor
Group default[14][15]
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[16][17][18]
Fovea type
single central fovea (displaced dorso-temporally from retinal centre)		Group default[16][17][18]
Night visionActivity pattern
diurnal
mode of 6 rows (of 6 rows): diurnal; not_nocturnal
Measured (not re-verified)[19][4][20][21][2][22]
Rods vs cones
cone-dominated
nocturnal -> rod-dominated; crepuscular / cathemeral / mixed -> mixed; diurnal -> cone-dominated
Derived[19][4][20][21][2][22]
Motion (flicker fusion)Flicker fusion frequency
88.5 Hz
median of 17 relatives in class Aves: Bubo virginianus, Melopsittacus undulatus, Passer domesticus, Taeniopygia guttata, Columba livia, Calypte anna
Group default[23][24][25][26][27]

Related animals

More birds: all birds with measured vision data.

Sources

  1. 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
  2. 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
  3. Ausprey I.J. & Ritland S. 2024. Eye morphology contributes to the ecology and evolution of the avian tree of life [Dataset]. Dryad. Digitised Table 7 of Ritland S. 1982, The allometry of the vertebrate eye, PhD dissertation, University of Chicago. Paper: Ausprey 2024 J Anim Ecol doi:10.1111/1365-2656.14141. doi.org/10.5061/dryad.3xsj3txq7
  4. Light conditions and the evolution of the visual system in birds (figshare dataset, SupplementaryDataset1). doi.org/10.6084/m9.figshare.22116371.v3
  5. Cantlay JC, Martin GR, McClelland SC, Potier S, O'Brien MF, Fernandez-Juricic E, Bond AL, Portugal SJ 2023. Binocular vision and foraging in ducks, geese and swans (Anatidae). Proc R Soc B 290: 20231213. ESM full data set (figshare collection 6781097).. doi.org/10.1098/rspb.2023.1213
  6. Lucas EA, Martin GR, Rocamora G, Portugal SJ. 2024. A seabird's eye view: visual fields of some seabirds (Laridae and Procellariidae) from tropical latitudes. The Science of Nature (Naturwissenschaften) 111. ESM 1.. doi.org/10.1007/s00114-024-01926-4
  7. Vision and foraging in structurally complex habitats: common moorhens (Gallinula chloropus). Ecology and Evolution 2026, e74060.. doi.org/10.1002/ece3.74060
  8. Pecsics T, Csorgo T. 2023. Ornis Hungarica 31(2):110-124. doi.org/10.2478/orhu-2023-0023
  9. Portugal SJ, Ozturk R, Murn CP, Potier S, Martin GR. 2023. Current Biology 33:R1142-R1143. doi.org/10.1016/j.cub.2023.09.016
  10. Potier S, Duriez O, Cunningham GB, et al. 2018. J Exp Biol 221:jeb177295. doi.org/10.1242/jeb.177295
  11. 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
  12. 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
  13. 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
  14. species_v1:Martin & Young 1983
  15. species_v1:Martin 1994
  16. 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
  17. 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
  18. 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
  19. Anderson SR, Wiens JJ. 2017. Out of the dark: 350 million years of conservatism and evolution in diel activity patterns in vertebrates. Evolution 71:1944-1959. Dryad doi:10.5061/dryad.fg700. doi.org/10.5061/dryad.fg700
  20. Choiniere JN, Neenan JM, Schmitz L, Ford DP, Chapelle KEJ, Balanoff AM, Sipla JS, Georgi JA, Walsh SA, Norell MA, Xu X, Clark JM, Benson RBJ. 2021. Evolution of vision and hearing modalities in theropod dinosaurs. Science 372:610-613. doi:10.1126/science.abe7941. Data: https://osf.io/teq73/. doi.org/10.1126/science.abe7941
  21. 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
  22. 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
  23. Boström JE, Dimitrova M, Canton C, Håstad O, Qvarnström A, Ödeen A. 2016. Ultra-rapid vision in birds. PLoS ONE 11(3): e0151099. S1 Table. doi.org/10.1371/journal.pone.0151099
  24. 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
  25. 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
  26. 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
  27. 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

Every value cites its sources (all sources). Data: catalogue-v1, built 2026-09-29. Accuracy notes: how accurate is this?