The evolution of darker wings in seabirds in relation to temperature-dependent flight efficiency. Issue 180 (7th July 2021)

• Record Type: Journal Article
• Authors: Rogalla, Svana; Nicolaï, Michaël P. J.; Porchetta, Sara; Glabeke, Gertjan; Battistella, Claudia; D'Alba, Liliana; Gianneschi, Nathan C.; van Beeck, Jeroen; Shawkey, Matthew D.
• Is Part Of: Journal of the Royal Society interface. Volume 18:Issue 180(2021)
• Publication Date: 2021-07-07
• Subjects: bird flight -- flight efficiency -- flight performance -- wing coloration -- countershading; Physical sciences -- Research -- Periodicals; Life sciences -- Research -- Periodicals; Interdisciplinary research -- Periodicals; 570.5
• DOI: 10.1098/rsif.2021.0236
• Languages: English
• ISSNs: 1742-5689

Abstract

Abstract : Seabirds have evolved numerous adaptations that allow them to thrive under hostile conditions. Many seabirds share similar colour patterns, often with dark wings, suggesting that their coloration might be adaptive. Interestingly, these darker wings become hotter when birds fly under high solar irradiance, and previous studies on aerofoils have provided evidence that aerofoil surface heating can affect the ratio between lift and drag, i.e. flight efficiency. However, whether this effect benefits birds remains unknown. Here, we first used phylogenetic analyses to show that strictly oceanic seabirds with a higher glide performance (optimized by reduced sink rates, i.e. the altitude lost over time) have evolved darker wings, potentially as an additional adaptation to improve flight. Using wind tunnel experiments, we then showed that radiative heating of bird wings indeed improves their flight efficiency. These results illustrate that seabirds may have evolved wing pigmentation in part through selection for flight performance under extreme ocean conditions. We suggest that other bird clades, particularly long-distance migrants, might also benefit from this effect and therefore might show similar evolutionary trajectories. These findings may also serve as a guide for bioinspired innovations in aerospace and aviation, especially in low-speed regimes.