Table 3.

Optical parameters and performance of avian species *

Common name
Species nameSourceCorneaAccommodationPupil constriction
Black guillemot Sivak et al., 1978 Radius: NARS: Air=0 D, Water=+5.0 D.NA
Cepphus grylle Power: NAMethods: retinoscope, forced submergence.
Effective index: 1.370N=6 birds.
Common goldeneye Sivak et al., 1985 Radius: NARange: 66.8 D, peaks in approx. 0.4 s.4→3.4
Bucephala clangula Power: 74.5Methods: electric elicitation of iris.
Effective index: NAN=1 bird.
Great cormorantPresent studyRadius: 6.7-5.4RS: Air=+0.45 D; Water=-1.79 D.Not apparent
Phalacrocorax carbo sinensis Power: 50.1-61.8Range: 64 D.
Effective index: NAMethods: voluntary dives. N=7 birds.
Double crested cormorant Sivak et al., 1977 Mean radius: 9.3RS: Air=0 D; Water=+3.0 D to +36.0 D.NA
Phalacrocorax auritus Mean power: 34.8Methods: retinoscopy, forced submergence.
Effective index: 1.37Anaesthetized underwater. N=3 birds.
Sivak et al., 1978 Radius: NARS: Air=0 D, Water=+3.0 D.NA
Power: NAMethods: forced submergence.
Effective index: 1.371N=2 birds.
Dipper Goodge, 1960 Radius: NARS: Air:=-2.0 D to +1.5 D; Water=+40 D to +44 D; induced: 46-48 D.NA
Cinclus mexicanus Power: NA
Effective index: NAMethods: forced submergence. N=2 eyes.
Hooded merganser Levy and Sivak, 1980 Radius: NARS: Air=0 D; induced=50 D.3→1
Mergus cucullatus Power: NAMethods: nicotine sulfate, excised eyes.In tens of seconds
Effective index: NAN=4 eyes.
Sivak et al., 1978 Radius: NARS: Air=+1.25 D; Water=+7.0 D.
Power: NA
Effective index: NA
Sivak et al., 1985 Radius: NARange 78.3 D; peaks in approx. 0.5 s.3.8→3.1
Power: 78.5Methods: electric stimulation of iris.4.6→3.9
Effective index: NAN=4 eyes.3.9→3.2
Mallard Levy and Sivak, 1980 Radius: NARS: Air=+1.0 D; induced -5 D.
Anas plathyrhynchos Power: NAN=8 eyes.
Effective index: 1.373
Sivak et al., 1978 Radius: NARS: Air=0 D; Water=45.0 D.Unpublished data
Power: NAN=2 birds.
Effective index: 1.373
Sivak et al., 1985 Radius: NARange 2.7 D.4.7→3
Power: 76.5Methods: electric elicitation of iris.
Effective index: 1.375N=2 birds.
Red headed duck Levy and Sivak, 1980 Radius: NARS: Air=0 D; induced 50 D.5→1
Aythya americana Power: NAMethods: nicotine sulfate on excised eyes.In minutes
Effective index: NAN=4 eyes.
Sivak et al., 1985 Radius: NARange 16 D; peaks in 0.15 s.2.9→2.3
Power: 83Methods: electric elicitation of iris.
Effective index: NAN=1 bird.
Wood duck Sivak et al., 1985 Radius: NARange 6.5 D; peaks in 0.3 s.4→2.7
Aix sponsa Power: 74.5Methods: electric elicitation of iris.
Effective index: NAN=1 bird.
Gray headed albatross Martin, 1998 Radius: 14.5NANA
Diomedea chrysostoma Power: 23
Effective index: NA
  • * Data exclude those of penguins.

  • Pupil constriction (mm) is during accommodation. RS, refractive state; NA, data not available.

  • Corneal power (measured in diopters) was calculated as F=337.5/R, where R (measured in mm) is corneal radius. Effective corneal refractive index was measured in meters.