Kingfisher

A flash of blue

The common kingfisher’s vivid blue back and orange belly make it one of the most recognizable birds in Europe and Asia. The blue is structural — produced by light scattering off microscopic feather structures — not pigment. In dim light, the bird looks dull; in sunlight, it flashes electric blue.

Hovering and diving

A kingfisher hunts by sitting on a branch over water, watching for fish, then either:

• Dropping straight down in a hand-grenade dive, with eyes closed at impact and a transparent third eyelid (the nictitating membrane) protecting the eye underwater.
• Hovering briefly above the water like a tiny falcon while the angle of the dive is calculated.

The dive must compensate for light refraction — the apparent position of a fish underwater is different from its actual position, because of how light bends at the water surface. Kingfishers calculate this correction automatically, hitting prey accurately even at steep angles.

A nose cone for a bullet train

In the 1990s, Japanese engineers redesigning the Shinkansen bullet train had a noise problem. Trains exiting tunnels at high speed produced loud booms (sonic compression waves) that disturbed nearby residents.

Eiji Nakatsu, the chief engineer (and an avid birdwatcher), noted that kingfishers dive from low-density air into high-density water with minimal splash and shock. The kingfisher’s sharply tapered, nearly tube-shaped bill produces a smooth pressure transition.

The new Shinkansen 500 series got a long, kingfisher-bill-shaped nose cone. The result: 10% less power consumption, 15% faster top speeds, and the elimination of tunnel boom. The bird-inspired engineering became a textbook biomimicry case.

Excavated nests

Kingfishers nest in horizontal tunnels they dig into riverbanks. The tunnel can be a meter long, ending in a chamber where the eggs are laid on bare earth — no nesting material at all. The chicks emerge after about 27 days into a fish-soaked, bone-littered burrow that’s not pleasant to enter (the parents have been bringing fish for weeks).

The tunneling is hard work and requires soft, vertical earthen banks — a habitat increasingly fragmented by river engineering.

Many kingfishers, many habitats

Despite the name, most of the 90+ kingfisher species worldwide aren’t fish-eaters. The “kingfisher” classification is a behavioral one based on the common kingfisher’s fishing habits, but most species in the family hunt insects, crabs, lizards, or even small mammals.

• Belted kingfisher (Megaceryle alcyon) — North American river kingfisher, much larger.
• Pied kingfisher (Ceryle rudis) — black-and-white African and Asian kingfisher, hovers extensively.
• Kookaburra (Dacelo) — Australian kingfishers that catch terrestrial prey, famous for their laughing call.
• Forest kingfishers — many tropical species that hunt insects in dense forest.

The diversity of kingfishers in Africa and Asia — including some species that never visit water — shows that the family’s name describes a single iconic species rather than the whole group.