| There is little comparative evidence in the evolution of highly specialized visual systems of ground foraging birds. My study assessed two key visual ecology components, the number and topography of the retinal ganglion cells, visual acuity, and the configuration of the visual fields, in four passerine and one non-passerine bird species. I used a histological approach to analyze the number and distribution of retinal ganglion cells and an opthalmoscopic technique to determine the extent of the visual field of five species; the European Starling, Brown-headed Cowbird, Mourning Dove, House Sparrow, and House Finch. The doves had the widest visual field and greatest visual acuity. Finches and doves had significant differences in ganglion cell density. Visual acuity was affected by eye size and ganglion cell density. All species studied had a similar retinal topography containing an area centralis. This data should allow for comparative studies in the future. |
