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The uniocular retinal field of Strix aluco is highly asymmetrical. The maximum width of 124 degrees is less than that recorded in any other vertebrate. Maximum retinal binocular field width equals 48 degrees and the optic axes diverge by 55 degrees. Maximum binocularity occurs above the bill whose tip lies outside of the visual field. The cyclopean retinal(More)
The Manx shearwater, Puffinus puffinus, is a pelagic sea bird which feeds from the surface of the sea and by shallow surface and plunge dives. Visits to breeding colonies are made at night. The mononuclear retinal field of the Manx shearwater eye is 148 degrees wide and is asymmetric with respect to the optic axis. The nasal and temporal hemi-fields equal(More)
Retinal visual fields were determined using an ophthalmoscopic reflex technique in two seabird species of the family Procellariidae: white-chinned petrel Procellaria aequinoctialis and antarctic prion Pachyptila desolata. The binocular fields of both species show a similar shape but they differ in size and in the position of the bill within the field. In(More)
Visual fields were determined in alert restrained birds using an ophthalmoscopic reflex technique. The region of binocular overlap is relatively small: maximum width of 20 degrees occurs approximately 15 degrees below the horizontal, and the field extends vertically through 80 degrees with the bill tip placed close to the centre. Monocular field width in(More)
A wave optical model was used to analyse the scattering properties of avian retinal oil droplets. Computations for the near field region showed that oil droplets perform significant light collection in cone photoreceptors and so enhance outer segment photon capture rates. Scattering by the oil droplet of the principal cone of a double cone pair, combined(More)
An ophthalmoscopic reflex technique has shown that in sedated pigeons maximum retinal binocular field width occurs approximately 20 degrees above the bill. The binocular field has a maximum width of 27 degrees and extends vertically by 130 degrees (90 degrees above the bill, 40 degrees below it). Both the bill and cere intrude into the binocular field.(More)
Procellariiforms are pelagic seabirds which fly close to the sea surface and feed either by taking items from the surface or by shallow diving. The retinal ganglion cells in five species (Manx shearwater, Puffinus puffinus, Kerguelen petrel, Pterodroma brevirostris, great shearwater, Puffinus gravis, broad-billed prion, Pachyptila vittata, and common diving(More)