Visual Fields in Short-Toed Eagles, Circaetus gallicus (Accipitridae), and the Function of Binocularity in Birds

  title={Visual Fields in Short-Toed Eagles, Circaetus gallicus (Accipitridae), and the Function of Binocularity in Birds},
  author={Graham R. Martin and Gadi Katzir},
  journal={Brain, Behavior and Evolution},
  pages={55 - 66}
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° occurs approximately 15° below the horizontal, and the field extends vertically through 80° with the bill tip placed close to the centre. Monocular field width in the horizontal plane is 139°, and the field is asymmetric about the optic axis. The cyclopean field extends through 260°, and the blind area above and behind the… 

Figures from this paper


The hypothesis that binocularity in birds is concerned with the contra lateral projec- tion of each eye rather than achieving disparate images of the same object from two eyes is supported.

Visual Fields and Foraging in Procellariiform Seabirds: Sensory Aspects of Dietary Segregation

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 to find differences in binocular field topography that can be correlated with the different foraging techniques that these birds employ when seeking a similar diet within the same environment.

Visual fields and their functions in birds

Among birds there are considerable interspecific differences in all aspects of visual fields. However, it is hypothesised that the topography of the frontal binocular portion of fields are of only

Visual fields in hornbills: precision‐grasping and sunshades

Retinal visual fields were determined in Southern Ground Hornbills Bucorvus leadbeateri and Southern Yellow-bills Tockus leucomelas (Coraciiformes, Bucerotidae) using an ophthalmoscopic reflex technique and indicated that the extent and position of the frontal binocular field is related to the degree to which vision is employed to control the positions of the bill or feet when they are used to take food items.

Feeding methods, visual fields and vigilance in dabbling ducks (Anatidae)

Visual fields were determined in two species of dabbling ducks (Anatini) and it is proposed that this interspecific difference in the proportion of time spent in vigilance behaviour may be an adaptive response to differences in the visual field topography of these species, particularly with respect to the presence/absence of a blind area to the rear of the head.

The visual fields of two ground-foraging birds, House Finches and House Sparrows, allow for simultaneous foraging and anti-predator vigilance

It is proposed that in these ground foragers, their relatively wide binocular fields could function to increase foraging efficiency by locating multiple rather than single food items prior to pecking events, suggesting that foraging and scanning are not mutually exclusive activities in these species.

Do American Goldfinches See Their World Like Passive Prey Foragers? A Study on Visual Fields, Retinal Topography, and Sensitivity of Photoreceptors

Overall, the visual system of American goldfinches showed characteristics of passive as well as active prey foragers, with a single-fovea configuration and a large degree of eye movement that would enhance food searching and handling with their relatively wide binocular fields.

The subtlety of simple eyes: the tuning of visual fields to perceptual challenges in birds

  • G. Martin
  • Biology
    Philosophical Transactions of the Royal Society B: Biological Sciences
  • 2014
It is argued that (i) the main drivers of differences in visual fields are associated with perceptual challenges that arise through different modes of foraging, and (ii) the primary function of binocularity in birds lies in the control of bill position rather than in theControl of locomotion.

The visual system of a Palaeognathous bird: Visual field, retinal topography and retino‐central connections in the Chilean Tinamou (Nothoprocta perdicaria)

The visual field, the retinal topography, and the pattern of retinal and centrifugal projections in the Chilean tinamou are investigated, stressing the conserved character of the visual projections' pattern within the avian clade.

Hawk Eyes I: Diurnal Raptors Differ in Visual Fields and Degree of Eye Movement

Between-species differences in visual field configuration in these diurnal raptors are consistent with prey searching strategies and degree of visual obstruction in the environment and variations in the degree of eye movement between species appear associated with foraging strategies.



Visual fields and eye movements in herons (Ardeidae).

The comprehensive nature of vision beneath the bill is probably closely associated with the herons' visually guided, stealthy, foraging techniques, which result in the single-strike capture of mobile, highly evasive prey.

Eye structure and amphibious foraging in albatrosses

  • G. Martin
  • Biology
    Proceedings of the Royal Society of London. Series B: Biological Sciences
  • 1998
Results indicate that the eyes are of an amphibious optical design suggesting that albatross vision is well suited to the visual pursuit of active prey both on and below the ocean surface.

The eye of a procellariiform seabird, the Manx shearwater, Puffinus puffinus: visual fields and optical structure.

A schematic model of the shearwater eye's optical system is presented, together with reanalysed data on the optical structure in the eye of the pigeon, Columba livia, which suggests that vision is used to guide the bill position during foraging.

The visual fields of the tawny owl, Strix aluco L

Conjugate and disjunctive saccades in two avian species with contrasting oculomotor strategies

  • J. WallmanJ. Pettigrew
  • Biology
    The Journal of neuroscience : the official journal of the Society for Neuroscience
  • 1985
It is found that both birds spend most of the time with their eyes confined to a small region of gaze, the primary position of gaze; in this position, the visual axes are much more diverged in the frogmouth than in the eagle, thereby giving it a larger total field of view at the expense of its binocular field.

Binocular stereopsis in an insect

The results demonstrate that mantids do indeed rely on binocular triangulation when estimating the distance of prey, and thus provide the first unequivocal evidence for stereoscopic vision in an invertebrate.

Stereopsis in toads

The present data suggest that toads do indeed make disparity measurements and should be added to the growing list of vertebrates known to achieve stereopsis, and that they have a mechanism for measuring depth within their extensive monocular field.

Directional Hearing in Owls: Neurobiology, Behaviour and Evolution

Birds are primarily active in the daytime, and most birds rarely venture forth from their roosts at night. Many species of owls, however, are nocturnal predators, and they exhibit a number of sensory

Binocular visual processing in the owl’s telencephalon

  • J. Pettigrew
  • Biology
    Proceedings of the Royal Society of London. Series B. Biological Sciences
  • 1979
It is suggested that for nervous systems only a very small number of possible solutions are possible to the problem of stereopsis, and single neurons recorded from the owl’s visual Wulst are surprisingly similar to those found in mammalian striate cortex.