PUB - Publikationen an der Universität Bielefeld

Measurements were made of the physical properties of the visual system of the zebra finch, a bird with laterally placed eyes. The use of the visual system in pecking and courtship behavior was examined. It was demonstrated that the optical axis and the fovea of the eye point in a direction about 62.degree. from the sagittal axis of the head. The visual field of each eye covers about 170.degree. in the horizontal plane. In the frontal region there is an overlap of about 30.degree.-40.degree. where the birds can see binocularly; caudally there is a 'gap' in the visual field of 60.degree.. The point of best binocular viewing is in the sagittal plane at 16.5.degree. below the beak. Concerning movement detection, the upper threshold is 540.degree./s for the binocular (frontal) part of the visual field and about 1100.degree./s for the monocular (lateral) part. Most fixations before pecking occur monocularly. A preference for one eye during pecking was not detected. During the courtship song, a male bird directs its head towards the female. The results are discussed in comparison with findings in pigeons and chickens.