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How does the common swift see?

The common swift (Apus apus) is a bird in the order Apodiformes. Its eyes belong to the vision type UV songbird, parrot and hummingbird.

Measured in this species: foveas 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.

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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 common swift (Apus apus), catalogue-v1
DialValueEvidenceSources
ColourColour 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]
SharpnessAcuity
10.88 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 9.88 mm
Estimated[3][4][5]
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[6][7][8][9][10][11][12][13][14]
Sharp zones (foveas)Number of foveas
1
retinal topography
Measured (not re-verified)[15]
Fovea type
temporal fovea only (no central pit)		Measured (not re-verified)[15]
Night visionActivity pattern
diurnal
mode of 7 rows (of 7 rows): cathemeral; diurnal; not_nocturnal
Measured (not re-verified)[16][17][18][19][20][21][22]
Rods vs cones
cone-dominated
nocturnal -> rod-dominated; crepuscular / cathemeral / mixed -> mixed; diurnal -> cone-dominated
Derived[16][17][18][19][20][21][22]
Motion (flicker fusion)Flicker fusion frequency
75 Hz
median of 1 relatives in order Apodiformes: Calypte anna
Group default[23]

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. Olsson P, Lind O, Mitkus M, Delhey K, Kelber A. 2021. Lens and cornea limit UV vision of birds - a phylogenetic perspective. J Exp Biol 224:jeb243129. doi.org/10.1242/jeb.243129
  5. Vertebrate eye-size compilation in Thomas et al. 2020 Dryad deposit (Thomas_vertebrates.csv). Primary sources: Howland et al. 2004 (n=313); Schmitz & Wainwright 2011 (n=265); Schmitz et al. 2013 (n=237); Hall 2008 (n=116); Veilleux & Kirk 2014 (n=91); Hall & Heesy 2011 (n=88); Liu et al. 2012 (n=66); Werner & Seifan 2006 (n=62); Lisney & Collin 2007 (n=46). doi.org/10.5061/dryad.1zcrjdfq7
  6. 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
  7. 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
  8. Vision and foraging in structurally complex habitats: common moorhens (Gallinula chloropus). Ecology and Evolution 2026, e74060.. doi.org/10.1002/ece3.74060
  9. Pecsics T, Csorgo T. 2023. Ornis Hungarica 31(2):110-124. doi.org/10.2478/orhu-2023-0023
  10. 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
  11. Potier S, Duriez O, Cunningham GB, et al. 2018. J Exp Biol 221:jeb177295. doi.org/10.1242/jeb.177295
  12. 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
  13. 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
  14. 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
  15. 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
  16. 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
  17. Angielczyk KD, Schmitz L 2014. Nocturnality in synapsids predates the origin of mammals by over 100 million years. Proc R Soc B 281: 20141642. Dryad doi:10.5061/dryad.1v8kj.. doi.org/10.1098/rspb.2014.1642
  18. Light conditions and the evolution of the visual system in birds (figshare dataset, SupplementaryDataset1). doi.org/10.6084/m9.figshare.22116371.v3
  19. 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
  20. 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
  21. Schmitz & Motani 2011. Nocturnality in dinosaurs inferred from scleral ring and orbit morphology. Science 332:705. Comparative data redeposited in Xing et al. 2020 supplementary information (Zenodo).. doi.org/10.5281/zenodo.3591994
  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. 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
  24. 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
  25. 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?