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- Title
Visual fields in the Stone-curlew Burhinus oedicnemus.
- Authors
MARTIN, GRAHAM R.; KATZIR, CADI
- Abstract
The Stone-curlew Burhinus oedicnemus is a short-billed terrestrial wading bird (Burhinidae; Charadriiformes) which forages primarily for surface living invertebrates in open, sparsely vegetated habitats during twilight and nighttime. Visual field topography in restrained alert birds was investigated using an ophthalmoscopic reflex technique. The visual fields have the following features: (1) Eye movements of significant amplitude appear to be absent. (2) The retinal binocular field is relatively small, with the bill placed near its centre. It extends vertically through 80° in the median sagittal plane with a maximum width of 18° occurring 5° above the bill. (3) With the head in a typical posture (eye-bill-tip angle approximately 15° below the horizontal), the binocular field stretches from 60° below to 20° above the horizontal. (4) The blind area behind the head is relatively narrow (15° at the horizontal), giving the bird near panoramic vision in the horizontal plane, but the widest blind area (32°) occurs directly above the head. (5) Monocular retinal fields in the horizontal plane are 182° wide and are asymmetric about the optic axis. (6) There is a blind sector of 7-12° at the margin of the optical fields, indicating that binocular field widths are not maximized. Interspecific comparisons of these visual field features suggest that the foraging of Stone-curlews is guided primarily by visual cues.
- Publication
Ibis, 1994, Vol 136, Issue 4, p448
- ISSN
0019-1019
- Publication type
Article
- DOI
10.1111/j.1474-919X.1994.tb01120.x