Foveal vision in fast-flying birds hunting on the wing
Processing rapid motion while maintaining high spatial acuity is a fundamental evolutionary challenge for the vertebrate visual system. Here, we investigated the structural adaptations enabling aerial insectivores - swifts (Apus apus) and swallows (Hirundo rustica, Delichon urbicum) - to track and capture prey at high speeds. We show that these phylogenetically distinct species share highly specialized temporal foveae that provide sharp frontal vision. Strikingly, this avian specialization converges on primate foveal architecture, featuring cones with long axons and a unique cluster of large, orthotopic ganglion cells (soma area [≥] 200 {micro}m{superscript 2}) surrounding a deep foveal pit. By tracking their large axons, we mapped their neural representation within the optic nerve and tectum. Despite the low abundance of these foveal cells, their substantial tectal magnification reflects high processing demands. This cluster of putative motion-sensitive ganglion cells suggests that foveal neural circuitry links high-acuity vision to rapid temporal processing in these birds.