Variations in cone photoreceptor abundance and the visual ecology of birds

Nathan S. Hart*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

221 Citations (Scopus)


The relative abundance and topographical distribution of retinal cone photoreceptors was measured in 19 bird species to identify possible correlations between photoreceptor complement and visual ecology. In contrast to previous studies, all five types of cone photoreceptor were distinguished, using bright field and epifluorescent light microscopy, in four retinal quadrants. Land birds tended to show either posterior dorsal to anterior ventral or anterior dorsal to posterior ventral gradients in cone photoreceptor distribution, fundus coloration and oil droplet pigmentation across the retina. Marine birds tended to show dorsal to ventral gradients instead. Statistical analyses showed that the proportions of the different cone types varied significantly across the retinae of all species investigated. Cluster analysis was performed on the data to identify groups or clusters of species on the basis of their oil droplet complement. Using the absolute percentages of each oil droplet type in each quadrant for the analysis produced clusters that tended to reflect phylogenetic relatedness between species rather than similarities in their visual ecology. Repeating the analysis after subtracting the mean percentage of a given oil droplet type across the whole retina (the 'eye mean') from the percentage of that oil droplet type in each quadrant, i.e. to give a measure of the variation about the mean, resulted in clusters that reflected diet, feeding behaviour and habitat to a greater extent than phylogeny.

Original languageEnglish
Pages (from-to)685-697
Number of pages13
JournalJournal of Comparative Physiology A
Issue number9
Publication statusPublished - 2001
Externally publishedYes


  • Avian retina
  • Colour vision
  • Cone photoreceptors
  • Oil droplets
  • Retinal topography


Dive into the research topics of 'Variations in cone photoreceptor abundance and the visual ecology of birds'. Together they form a unique fingerprint.

Cite this