Exploring the visual system of the black Grouse (Lyrurus tetrix): Combining experimental and molecular approaches to inform strategies for reducing collisions

Understanding the visual systems of birds can inform conservation efforts and mitigate anthropogenic threats, such as collisions with man-made structures. This study investigates the visual abilities of the black grouse (Lyrurus tetrix), a European mountain bird highly vulnerable to collisions. Using an integrative approach, we assessed key visual components including visual field configuration, spatial resolution, contrast sensitivity, and spectral sensitivity. Behavioral assays revealed that black grouse have an extensive visual field with a wide binocular overlap and minimal blind spots, allowing for efficient predator detection and foraging. However, their spatial resolution and contrast sensitivity are relatively low, consistent with other prey species. Molecular analyses identified four cone opsins (SWS1, SWS2, Rh2, and LW) with spectral sensitivities spanning ultraviolet to long wavelengths (393 to 546 nm). These findings highlight the black grouse's ability to detect UV light, likely aiding in food detection. Our results emphasize the need for collision mitigation measures tailored to species-specific visual abilities, including diverters designed with enhanced UV reflectance and increased visibility. This study advances our understanding of avian vision and provides critical insights to guide conservation strategies for reducing bird collisions in alpine habitats.