For more than a millennium, artists have used kingfishers’ vibrant blue feathers in art, fashion and decorations, but what is behind this vibrant palette of shades of blue?
Kingfishers are small bright blue and orange birds of slow-moving or still water. They fly rapidly, low over water, and hunt fish from riverside perches.
To answer this, scientists have investigated cultural objects decorated with feathers to reveal the nanoscale architecture that gives rise to their colours. The findings are set to advance our understanding of craft, historical context, materiality and degradation.
Using synchrotron X-ray methodologies and nanotechnology-based analytical methods, Northwestern University scientists have uncovered how nanoscale, spongy architectures — rather than pigments — within the feathers give rise to these birds’ vibrant colours.
Lead researcher Maria Kokkori discussed these stunning images during a panel discussion at the recent American Association for the Advancement of Science (AAAS) annual meeting in Phoenix.
The panel “Nature’s Nanotech: Structural Color in Chinese Featherworks” took place on Saturday, February 14 as part of a panel titled “Lost Colors Found: How Science is Retelling History.”
“Long admired in Chinese poetry and art, kingfisher feathers have amazing optical properties,” Kokkori says. “Our discoveries not only enhance our understanding of historical materials but also reshape how we think about artistic and scientific innovation, and the future of sustainable materials.”
While kingfishers are usually thought to live near rivers and eat fish, many species live away from water and eat small invertebrates. Like other members of their order, they nest in cavities, usually tunnels dug into the natural or artificial banks in the ground.
Kokkori is an associate research professor of electrical and computer science at Northwestern’s McCormick School of Engineering and senior scientist at the Center for Scientific Studies in the Arts, a collaboration between Northwestern and the Art Institute of Chicago.
The brightness of the colours is caused by the structure of the feathers, which causes scattering of blue light (the Tyndall effect – light scattering by particles in a colloid). Kingfishers appear blue due to a phenomenon called structural coloration, where microscopic structures in their feathers interact with light to produce vivid colours, rather than relying on pigments.
The remarkable optical properties of kingfisher feathers and their long history in art. In Qing China, artisans incorporated iridescent kingfisher feathers into decorative works using the tian-tsui technique.
By cutting and carefully orienting feather fragments to preserve and enhance their interaction with light, artists intensified the feathers’ dazzling blue hues — exploiting complex optical effects centuries before science could explain them.
Kokkori’s team examined several cultural heritage objects, including tian-tsui screens, with advanced tools, revealing the feathers’ nanostructures in unprecedented detail. Although the nanostructures have no colors of their own, the sponge-like shapes reflect and scatter light. The eyes then perceive this light as shimmering colours.
