Inter-individual differences in foveal shape in a scavenging raptor, the black kite Milvus migrans

Research output: Contribution to journalArticle


Birds, and especially raptors, are believed to forage mainly using visual cues. Indeed, raptors (scavengers and predators) have the highest visual acuity known to date. However, scavengers and predators differ in their visual systems such as in their foveal configuration. While the function of the foveal shape remains unknown, individual variation has never been quantified in birds. In this study, we examined whether foveal shape differs among individuals in relation to eye size, sex, age, eye (left or right) and genetic proximity in a scavenging raptor, the black kite Milvus migrans. We assessed foveal shape in 47 individuals using spectral domain optical coherence tomography (OCT) and geometric morphometric analysis. We found that foveal depth was significantly related to eye size. While foveal width also increased with eye size, it was strongly related to age; younger individuals had a wider fovea with a more pronounced rim. We found no relationship between foveal shape and genetic proximity, suggesting that foveal shape is not a hereditary trait. Our study revealed that the shape of the fovea is directly linked to eye size and that the physical structure of the fovea may develop during the entire life of black kites.


  • Simon Potier
  • Mindaugas Mitkus
  • Thomas J. Lisney
  • Pierre François Isard
  • Thomas Dulaurent
  • Marielle Mentek
  • Raphaël Cornette
  • David Schikorski
  • Almut Kelber
External organisations
  • Vilnius University
  • Paul Valéry University of Montpellier
  • Centre Hospitalier Vétérinaire Saint-Martin
  • Muséum National d'Histoire Naturelle (Sorbonne Universités)
  • Université des Antilles
  • Laboratoire Labofarm
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Evolutionary Biology
Original languageEnglish
Article number6133
JournalScientific Reports
Issue number1
Publication statusPublished - 2020
Publication categoryResearch