Anomalous binocular vision in African Harrier-Hawks

Steven J Portugal; Rana Ozturk; Campbell P Murn; Simon Potier; Graham R Martin

doi:10.1016/j.cub.2023.09.016

Anomalous binocular vision in African Harrier-Hawks

Curr Biol. 2023 Nov 6;33(21):R1142-R1143. doi: 10.1016/j.cub.2023.09.016.

Authors

Steven J Portugal¹, Rana Ozturk², Campbell P Murn³, Simon Potier⁴, Graham R Martin⁵

Affiliations

¹ Department of Biological Sciences, School of Life and Environmental Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK. Electronic address: Steve.Portugal@rhul.ac.uk.
² Department of Biological Sciences, School of Life and Environmental Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK; School of Biological Sciences, University of Reading, Whiteknights, Reading, Berkshire RG6 6AS, UK.
³ School of Biological Sciences, University of Reading, Whiteknights, Reading, Berkshire RG6 6AS, UK; The Hawk Conservancy Trust, Sarson Lane, Weyhill, Andover, Hampshire SP11 8DY, UK.
⁴ Les Ailes de l'Urga, 72 rue de la vieille route, 27320 Marcilly la Campagne, France; Lund Vision Group, Department of Biology, Lund University, Sölvegatan 35, S-22362 Lund, Sweden.
⁵ School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.

PMID: 37935124
DOI: 10.1016/j.cub.2023.09.016

Abstract

An animal's visual field is the three-dimensional space around its head from which it can extract visual information at any instant¹. Bird visual fields vary markedly between species, and this variation is likely to be driven primarily by foraging ecology¹^,²^,³. The binocular visual field is the region in which the visual fields of the two eyes overlap; thus, objects in the binocular field are imaged by both eyes simultaneously. The binocular field plays a pivotal role in the detection of symmetrical optic flow-fields, providing almost instantaneous information on the direction of travel and the time to contact a target towards which the head or feet is travelling; thus, information from the binocular field is crucial in guiding key foraging behaviours²^,³. Here, we demonstrate an unusual visual field and binocular extent above the head in African Harrier-Hawks, also known as Gymnogenes (Polyboroides typus) compared to 18 other members of the Accipitridae⁴^,⁵. We argue that the observed visual field can be attributed to the unusual and specific foraging behaviour of African Harrier-Hawks.

Publication types

Letter

MeSH terms

Animals
Eagles*
Eye
Hawks*
Vision, Binocular
Visual Fields