Visual Performance of Pigeons

Even superficial observation of birds in their natural environment suggests that the performance of their visual system is at least on a par with ours. Many detailed field studies amply confirm this inference. During a 3-year study of free-ranging skylarks (Alauda arvensis), circumstantial evidence indicated that their vision was superior to that of the observer in a variety of situations (Delius, 1963). The skylarks could clearly recognize each other individually at a range of 30 m or more purely by visual cues, while the observer could only do so unreliably when aided by a 30x telescope . Skylarks spotted merlins or pigeon hawks (Falea ealumbarius) flying overhead at heights where the observer positively could not resolve them without the aid of 8 X binoculars. Perhaps these songbirds' most remarkable performance was the detection of minute, usually camouflaged insect prey in dune sand and vegetation. As hard as the observer tried, helped by a 5 X magnifying lens, his hunting success rate was at best only a tenth that of skylarks. Casual observations of free-ranging domestic pigeons (Calumba livia) indicate that their vision is, if anything, better than that of skylarks. We are thus inclined to believe that the measures of visual capabilities that we obtain in the laboratory are still only a pale reflection of the real performance of the pigeon's visual system.